Gulf War Illnesses
Preliminary Assessment of DOD Plume Modeling for U.S. Troops' Exposure to Chemical Agents Gao ID: GAO-03-833T June 2, 2003Of the approximately 700,000 veterans of the Persian Gulf War, many have undiagnosed illnesses. The Department of Defense (DOD) and the Central Intelligence Agency (CIA) have concluded, using computer plume modeling, that no U.S. troops were exposed to hazardous substances because plumes--clouds of chemical warfare agents--could not have reached the troops. GAO was asked to assess DOD and CIA plume modeling to determine whether DOD's conclusions could be supported. GAO's final assessment will be reported at a later date.
DOD's conclusion as to the extent of U.S. troops' exposure is highly questionable because DOD and CIA plume modeling results are not reliable. In general, modeling is never precise enough to draw definitive conclusions, and DOD did not have accurate information on source term (such as the quantity and purity--concentration--of the agent) and meteorological conditions (such as the wind and weather patterns), essential to valid modeling. In particular, the models DOD selected were not fully developed and validated for long-range environmental fallout; the source term assumptions were not accurate; the plume height was underestimated; the modeling only considered the effects on health of a single bombing; field-testing at Dugway Proving Ground did not realistically simulate the actual bombing conditions; and divergence in results among models. DOD's conclusion, based on the findings of epidemiological studies--that there was no significant difference between rates of illness for exposed versus not exposed troops--is not valid. In the epidemiological studies, the results of DOD's flawed modeling served as a key criterion for determining the exposure classification--exposed versus not exposed to chemical agents--of the troops. Such misclassification is a serious problem that can have two types of effects: First, if misclassification affects both comparison groups qually (nondifferential classification--equally in the exposed and unexposed groups), it may water down the results so that important associations are missed. Second, if misclassification affects one group more than the other (differential misclassification), it may introduce bias that obscures important associations or creates false associations. Consequently, the misclassification in the studies resulted in confounding--that is, distorting--the results, making the conclusion invalid.
GAO-03-833T, Gulf War Illnesses: Preliminary Assessment of DOD Plume Modeling for U.S. Troops' Exposure to Chemical Agents
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Testimony:
Before the House Subcommittee on National Security, Emerging Threats,
and International Relations, Committee on Government Reform:
United States General Accounting Office:
GAO:
For Release on Delivery Expected at 1:00 p.m. EDT:
Monday, June 2, 2003:
Gulf War Illnesses:
Preliminary Assessment of DOD Plume Modeling for U.S. Troops' Exposure
to Chemical Agents:
Statement of Keith Rhodes, Chief Technologist
Center for Technology and Engineering, Applied Research and Methods:
GAO-03-833T:
GAO Highlights:
Highlights of GAO-03-833T, a testimony before the House Subcommittee
on National Security, Emerging Threats, and International Relations,
Committee on Government Reform
Why GAO Did This Study:
Of the approximately 700,000 veterans of the Persian Gulf War, many
have undiagnosed illnesses. The Department of Defense (DOD) and the
Central Intelligence Agency (CIA) have concluded, using computer plume
modeling, that no U.S. troops were exposed to hazardous substances
because plumes”clouds of chemical warfare agents”could not have
reached the troops. GAO was asked to assess DOD and CIA plume modeling
to determine whether DOD‘s conclusions could be supported. GAO‘s
final assessment will be reported at a later date.
what GAO Found:
DOD‘s conclusion as to the extent of U.S. troops‘ exposure is highly
questionable because DOD and CIA plume modeling results are not
reliable. In general, modeling is never precise enough to draw
definitive conclusions, and DOD did not have accurate information on
source term (such as the quantity and purity”concentration”of the
agent) and meteorological conditions (such as the wind and weather
patterns), essential to valid modeling. In particular, the models DOD
selected were not fully developed and validated for long-range
environmental fallout; the source term assumptions were not accurate;
the plume height was underestimated; the modeling only considered the
effects on health of a single bombing; field-testing at Dugway Proving
Ground did not realistically simulate the actual bombing conditions;
and divergence in results among models.
DOD‘s conclusion, based on the findings of epidemiological studies--
that there was no significant difference between rates of illness for
exposed versus not exposed troops--is not valid. In the
epidemiological studies, the results of DOD‘s flawed modeling served
as a key criterion for determining the exposure classification”exposed
versus not exposed to chemical agents”of the troops. Such
misclassification is a serious problem that can have two types of
effects: First, if misclassification affects both comparison groups
equally (nondifferential classification-- equally in the exposed and
unexposed groups), it may water down the results so that important
associations are missed. Second, if misclassification affects one
group more than the other (differential misclassification), it may
introduce bias that obscures important associations or creates false
associations. Consequently, the misclassification in the studies
resulted in confounding”that is, distorting”the results, making the
conclusion invalid.
www.gao.gov/cgi-bin/getrpt?GAO-03-833T.
To view the full product, including the scope
and methodology, click on the link above.
For more information, contact Keith Rhodes at (202) 512-6412 or
rhodesk@gao.gov.
[End of section]
Mr. Chairman and Members of the Subcommittee:
We are pleased to be here today to present our preliminary assessment
of the plume modeling conducted by DOD and CIA to determine the number
of U.S. troops that might have been exposed to the release of chemical
warfare agents during the Gulf War in 1990. We will report the final
results of this study at a later date.
As you know, many of the approximately 700,000 veterans of the Persian
Gulf War have undiagnosed illnesses since the war's end in 1991. Some
fear they are suffering from chronic disabling conditions because of
wartime exposures to vaccines, as well as chemical warfare agents,
pesticides, and other hazardous substances with known or suspected
adverse health effects. Available bomb damage assessments during the
war showed that of the 21 sites bombed in Iraq--categorized by
intelligence agencies as nuclear, biological, or chemical facilities--
16 had been destroyed by bombing. Some of these sites were near the
areas where U.S. troops were located.
When the issue of the possible exposure of troops to low levels of
chemical warfare agents was first raised, during the summer of 1993,
the Department of Defense (DOD) and the Central Intelligence Agency
(CIA) concluded that no U.S. troops were exposed because (1) there were
no forward-deployed chemical warfare agent munitions and (2) plumes--
clouds of chemical warfare agents--from the bombing that destroyed the
chemical facilities could not have reached the troops.
This position was maintained until 1996, when it became known that U.S.
troops destroyed a stockpile of chemical munitions after the Gulf War
in 1991, at a forward-deployed site, Khamisiyah, in Iraq. Consequently,
DOD and the CIA made several modeling efforts to estimate the number of
troops that might have been potentially exposed to chemical warfare
agents. But recognizing that actual data on the source term--such as
the quantity and the purity (concentration) of the agent--and
meteorological conditions--such as the wind and the weather patterns--
were not available,[Footnote 1] DOD and CIA conducted field-testing and
modeling of bombing sites at Khamisiyah, in 1996 and 1997, to determine
the size and path of the plume, as well as the number of U.S. troops
exposed to the plume. During these initial modeling efforts, DOD asked
the Department of Energy's Lawrence Livermore National Laboratories
(LLNL) to also conduct modeling. In 1997, DOD and CIA also combined a
number of their own individual modeling efforts into a composite and
conducted additional plume modeling of the bombing sites at Al
Muthanna, Muhammadiyat, and Ukhaydir. Subsequently, in 2000, DOD
revised its modeling of Khamisiyah.
In our testimony today, at your request, my remarks will focus on our
preliminary findings of DOD and CIA plume modeling during the Gulf War.
Specifically, I will address the validity of the following DOD
conclusions:
* based on DOD plume modeling efforts, that the extent to which U.S.
troops were exposed was minimal and:
* based on findings of government-funded epidemiological studies, that
there was no significant difference as to the rate of illness between
troops that were exposed to chemical warfare agents versus those not
exposed.
Our work thus far has involved interviews with agency officials and
experts in this area, reviews of relevant documents and literature, and
a review of DOD's methodology and analyses of plume modeling. Our work
has been performed in accordance with generally accepted government
auditing standards.
Summary:
DOD's conclusion as to the extent of U.S. troops' exposure--based on
DOD and CIA plume modeling--is highly questionable because the results
of the modeling are unreliable. In general, modeling is never precise
enough to draw definitive conclusions, and DOD did not have accurate
information on source term and meteorological conditions.
We have several reasons for this assessment: First, DOD selected models
that were not fully developed and validated for modeling long-range
environmental fallout. Second, some of the assumptions regarding the
source term data used in the modeling were not accurate--based on
incomplete information, data that were not validated, and testing that
did not realistically simulate the actual conditions at Khamisiyah. For
example, the CIA calculated the agent purity in 1991 to be 50 percent
at Khamisiyah, but 18 percent at Al Muthanna and about 15 percent at
Muhammadiyat. The CIA did not independently validate or establish agent
purity levels based on empirically driven analyses, and relied on
UNSCOM reporting for these rates. This assessment of the agent purity
rate at Al Muthanna was questioned by a DOD official. We plan to
examine the validity of the methodology used to calculated the rate of
degradation.
Third, the plume height was underestimated, which resulted in
discounting the impact of certain meteorological conditions, such as
high-speed winds at nighttime, when many of the bombings occurred. This
would have a dramatic effect on the distance the chemical agent
traveled. Moreover, according to an internal DOD memo, plume height in
one case at Al Muthanna was arbitrarily determined by a DOD official to
be 10 meters. At Muhammadiyat and Ukhaydir, plume heights were
estimated to be the height of the munition or the munition stack.
However, independent field-testing demonstrated that a single 1,000-
pound bomb would create plume height in excess of 400 meters above the
ground. Fourth, DOD, in its modeling, only considered the effect of a
single bombing of the sites on the health of the U.S. troops. But DOD
did not take into account the cumulative effects of repeated bombings
of the sites on troops' health. Fifth, post-war field-testing done at
Dugway Proving Ground, to estimate the source term data and plume
height, did not realistically simulate the actual conditions of
bombings at any of the sites. The simulation occurred under conditions
that were not comparable to those that existed at Khamisiyah. For
example, there were differing seasonal and meteorological conditions,
differences in rocket construction, and lesser quantities of rockets.
These differences result in multi-variable uncertainty that cannot be
resolved. Finally, there was a great divergence among the various
models DOD selected with regard to the size and path of the plume and
the extent to which troops were exposed. Combining the results of
various models masked the highly divergent predictions among the
individual models regarding the size and path of the plume. The results
of LLNL model which showed the largest area of coverage were
disregarded and not included in the composite model.
DOD's conclusion that there were no significant differences in the rate
of illness between exposed and non-exposed troops is questionnable. DOD
based this conclusion on the findings of epidemiological studies, in
which DOD modeling was flawed. In addition, the modeling results served
as a key criterion for classifying troops that were ill and had been
exposed compared with troops that were ill and determined not to have
been exposed. However, the troops classified as non-exposed might have
been exposed. Such misclassification is a serious problem that can have
two types of effects. First, if misclassification affects both
comparison groups equally (non-differential classification--equally in
the exposed and unexposed groups), it may water down the results so
that important associations are missed. Second, if misclassification
affects one group more than the other (differential misclassification),
it may introduce bias that obscures important associations or creates
false associations. Consequently, the misclassification in the studies
resulted in confounding--that is, distorting--the results.
Background:
In March 1991, after the conclusion of the Gulf War, U.S. Army
demolition units destroyed munitions at the Khamisiyah storage site--
which included a bunker and an open pit--in southeastern Iraq. Later,
through inspections conducted by the United Nations Special Commission
(UNSCOM) in Iraq, it was discovered that hundreds of 122-millimeter
rockets destroyed at Khamisiyah contained the nerve agents sarin and
cyclosarin. U.S. and coalition forces also bombed many other known or
suspected Iraqi chemical warfare research, materiel, storage, and
production sites. According to DOD and the CIA, coalition air strikes
resulted in damage to filled chemical munitions at only two facilities
in central Iraq, Al Muthanna bunker 2 and Muhammadiyat, and at the
Ukhaydir ammunition storage depot in southern Iraq. At Muhammadiyat,
munitions containing an estimated 2.9 metric tons of sarin and
cyclosarin and 15 metric tons of the chemical agent mustard were
damaged during the air strikes. At Al Muthanna, munitions containing an
estimated 17 metric tons of sarin and cyclosarin were damaged during
the air strikes.
According to DOD, the U.S. Government did not immediately make the
connection between the chemical munitions found by UNSCOM at Khamisiyah
and U.S. demolition bombings there. However, in 1996, concerns raised
by the Presidential Advisory Committee on Gulf War Illnesses prompted
the CIA to examine this issue.[Footnote 2] The CIA contracted with the
Science Applications International Corporation (SAIC) to conduct the
initial analysis and modeling of the bombing of chemical munitions in
Khamisiyah bunker 73. The CIA's first report, published in August 1996,
modeled the potential release of agents from bunker 73. The CIA and DOD
jointly published a second report in September 1997. In this report,
they combined the results of five different dispersions (for example,
the size and path of the plume) and meteorological models to determine
the extent of the plume from bombing of chemical munitions in
Khamisiyah. In 2000, DOD published the results of a new modeling of the
Khamisiyah site, using updated CIA source assessments and revising the
hazard area.
Information Needed for Modeling the Effects of Chemical Warfare Agents:
In chemical plume modeling, simulations are produced that recreate or
predict the size and path of the plume, including the potential hazard
area, and the potential effect on the health of the exposed population.
Modeling requires accurate information on:
* source term characteristics, properties (for example, vapor pressure,
flash point, size of particles, persistency, and toxicity information),
and rate of the agent release;
* temporal characteristics of the period of release (for example,
whether the initial release of chemical agent occurred during daylight
hours when it might rapidly disperse into the surface air or at night
when differing dispersion patterns would exist depending on terrain and
the height of the release);
* accurate collection of data that drive the meteorological models,
such as temperature, humidity, barometric pressure, dew point, wind
velocity and direction at varying altitudes, and other related
measurements of weather conditions during the modeled period;
* data from global weather models to simulate large-scale weather
patterns and from regional and localized weather models to simulate the
weather in the area of the chemical agent release and throughout the
area of dispersion; and:
* information regarding the location of potentially exposed
populations, animals, crops or other assets that may be affected by
releases of the agent.
Types of Models Used:
The modeling of various chemical agent releases during the 1991 Persian
Gulf War included global-scale models, such as the National Centers for
Environmental Prediction Global Data Assimilation System (GDAS) and the
Naval Operational Global Atmospheric Prediction System (NOGAPS).
Regional and local weather models used included the Coupled Ocean-
Atmosphere Mesoscale Prediction System (COAMPS), the Operational
Multiscale Environment Model with Grid Adaptivity (OMEGA), and the
Mesoscale Model Version 5 (MM5).
Transport and diffusion models (often simply called dispersion models)
were also used. They project both the path of the chemical agents after
release and the degree of hazard posed by the agents. For example, the
modeling of various releases during the 1991 Gulf War included
dispersion models, such as the Second-order Closure Integrated Puff
(SCIPUFF) model along with its Hazard Prediction and Assessment
Capability (HPAC) component; the Vapor, Liquid, and Solid Tracking
(VLSTRACK) model; the Non-Uniform Simple Surface Evaporation Model
(NUSSE); and the Atmospheric Dispersion by Particle-in-Cell (ADPIC)
model.
DOD's Conclusions Regarding the Extent of Exposure of U.S. Troops Are
Highly Questionable:
DOD's conclusion as to the extent of U.S. troops' exposure--based on
DOD and CIA plume modeling--is highly questionable because the results
of the modeling are unreliable. The modeling conducted was not precise
enough to draw definitive conclusions regarding the size and path of
the plume. We found six reasons to question the conclusions: First, the
models selected were not fully developed and validated. Second, the
assumptions regarding the source term used in the modeling were not
accurate. Third, the plume height was underestimated. Fourth, DOD
modeling only considered the effects of a single bomb on health. Fifth,
post-war field testing done at Dugway Proving Ground did not
realistically simulate the actual conditions of bombing at any site.
And, finally, there was a great divergence among the various models DOD
selected with regard to the size and path of the plume.
The Models Selected Were Not Fully Developed and Validated:
DOD and CIA officials selected in-house models for use in plume
modeling (see appendix 1). In the case of Khamisiyah and other sites,
DOD models--such as the VLSTRACK and HPAC/SCIPUFF dispersion models--
were not fully developed and validated for environmental fallout at the
time of their selection. In particular, these models were not
appropriate for long-range tracking of chemical agents.
VLSTRACK was developed primarily as a tactical decision aid for
predicting hazards resulting from the release of chemical and
biological agents in a military environment. Modeling experts at the
Naval Surface Center told us that the two-month DOD panel reanalysis
and modeling was a developmental effort because existing models did not
have the capability to perform the required projections. Considerations
of potential illness from low-level exposure to chemical agents
resulting from nerve and blister agents accidentally released in Iraq
required extensive extensions and modifications to some of the
methodology in VLSTRACK.
HPAC was developed jointly by the Defense Intelligence Agency and the
then Defense Special Weapons Agency (now known as DTRA) and was
specifically tailored to do counterproliferation contingency planning.
In a 1998 scientific review and evaluation of SCIPUFF, which is an
integral part of HPAC, the National Oceanic and Atmospheric
Administration's (NOAA's) Air Resources Laboratory stated that SCIPUFF
is probably better suited for short-range (about 10 kilometers)
dispersion applications rather than for long-range transport modeling.
Among the limitations cautioned regarding the use of the HPAC model are
that does not provide a definitive answer due to uncertainties about
transport, location, and weather.
In addition, based on the DOD modeling effort, it is evident that a
group using the VLSTRACK model might receive a significantly different
prediction from that of a group using the HPAC model. And neither of
these models has sufficient fidelity--that is, reliability--to permit
the conclusion that the actual hazard area--that is, path of the plume-
-is confined to the predicted hazard area. In a September 1998 memo,
the Deputy to the Secretary of Defense for Counterproliferation and
Chemical/Biological Defense cited a DOD panel study team, which found
that the VLSTRACK and HPAC models generate hazard predictions that are
significantly different from each other. The memo noted, "This occurred
even when the source terms and weather inputs are as simple and as
identical as possible. In operational deployment, the average model
user could obtain different answers for the same threat.":
With regard to meteorological models, according to a 1997 memo from the
Director of NOAA's Air Resources Laboratory to DOD, the selection of
models was dominated by in-house, that is, DOD, models that were not
well known outside of DOD. The Director noted that there were three
mainstream mesoscale models available and well accepted for deriving
site-specific flow conditions from large-scale meteorological
information: MM5, RAMS, and Eta. At that time, OMEGA and COAMPS were
too new and not well accepted outside of DOD circles. OMEGA was still
under development, and a Peer Review Panel on the 1997 Khamisiyah
modeling reported that there were major problems with the OMEGA model.
For example, there were physically impossible aspects to the OMEGA
model solutions and major errors in its simulations. For the analysis
done for Khamisiyah and Al Muthanna, a DOD technical review panel found
that OMEGA consistently under-predicted surface wind speeds by a factor
of 2 to 3 when compared with actual observations collected at five
World Meteorological stations in the area.
The Source Term Assumptions Were Not Accurate:
There were significant uncertainties in the source term used in the
plume modeling at Khamisiyah. DOD and the CIA made assumptions about
the source term based on field-testing, intelligence information,
imagery, UNSCOM inspections, and Iraqi declarations to UNSCOM. However,
these assumptions were based on incomplete information, data that were
not validated, and testing that did not realistically simulate the
actual conditions at Khamisiyah.
In its initial modeling of the demolition of chemical munitions at
Khamisiyah, the CIA did not have accurate and precise information as to
how rockets with chemical warheads would be affected by open pit
demolition, compared with bunker demolition. This lack of information
included the number of rockets, agent purity, and amount of agent
released in the atmosphere, agent reaction in an open-pit demolition,
and prevailing meteorological conditions. A DOD panel also found a lack
of information,[Footnote 3] that is, substantial uncertainties
regarding the number of damaged rockets that might have released
chemical agents and how fast the nerve agents--sarin and cyclosarin,
which were mixed together in the rockets--were released. Some of these
agents may have leaked from rockets into the soil or into the wood of
the boxes that contained the rockets and evaporated over time. The
panel also found that the CIA and SAIC analyses used what were
essentially guesses for the lack of data. For example, the numbers of
rockets were based on what was known to be there before the demolition
and what was found by the UNSCOM during their inspections, but,
according to a DOD panel, the numbers varied by a factor of 5 or 6.
In addition, this panel recognized that meteorological data were
limited because there were relatively few observations, and these were
made far from the Khamisiyah site. Observations were few because Iraq
stopped reporting weather station measurement information to the World
Meteorological Organization in 1981. As a result, data on the
meteorological conditions during the Gulf War were sparse. The only
data that were available were for the surface wind observation site, 80
to 90 kilometers away, and the upper atmospheric site, about 200
kilometers away. The panel also recognized that wind patterns could
contain areas of bifurcation--lines where winds move in one direction
on one side and in another direction on another side--which also move
over time and are different at different altitudes.
Source term assumptions on agents (sarin and cyclosarin) purity
established for the four sites--Khamisiyah, as well as Al Muthanna,
Muhammadiyat, and Ukhaydir--differed widely. Discrepancies between the
Khamisiyah purity data and the Al Muthanna and Muhammadiyat data were
not adequately resolved. The agents were assumed to be purer in
February 1991 at Al Muthanna than in January at Muhammadiyat and purer
still in March at Khamisiyah. In each case, agent purity was a key
factor in the DOD and CIA methodology for determining the amount of
agents released. Since the purity of the sarin and cyclosarin was used
as a factor in calculating the amount of agents released, purity is
critical in compounding the uncertainty of the modeling. For example,
for modeling purposes, 10 tons of agent with a purity of 18 percent
would be represented as only 1.8 tons of agent. The CIA did not
independently validate or establish agent purity levels based on
empirically driven analyses, and relied on UNSCOM reporting for these
rates. This assessment of the agent purity rate at Al Muthanna was
questioned by a DOD official, who noted in a memo, "Why we use the 18
percent purity instead of the 50 percent number available in public
sources, and why we treat GF like GB when there are documents that
mention the higher toxicity are not easily deferred with 'because the
CIA says so.' I think the GF vs. GB numbers accepted by the EPA or CDC
or whatever is the competent authority, but the purity number is
problematic." We plan to examine the validity of the methodology used
to calculated the rate of degradation.
In addition, according to Iraqi production records obtained by UNSCOM,
the agent purity at Khamisiyah, in early January 1991, was about 55
percent. The agent subsequently degraded to 10-percent purity by the
time laboratory analysis had been completed on samples taken by UNSCOM
from one of the rockets in October 1991. On the basis of the sample
purity and indications that the degradation rate for sarin and
cyclosarin are similar, the CIA assessed that the ratio of sarin to
cyclosarin when the munitions were blown up in March 1991 was the same
as that sampled in October 1991--3:1. According to the CIA, assuming a
conservative exponential degradation of the sarin and cyclosarin, the
purity on the date of demolition, 2 months after production, was
calculated to be about 50 percent.
At Al Muthanna, however, where the agent was stored in a bunker, the
CIA estimated the chemical warfare agent had deteriorated to
approximately 18 percent purity by the time that bunker 2 was
destroyed, in early February 1991, leaving about 1600 kilograms (1.6
metric tons) of viable sarin. The CIA based its estimate on UNSCOM's
analysis of Iraqi purity data and supporting information, which stated
that the munitions were filled with the agent in 1988 and that the
maximum purity for the 1988 agent was 18 percent in 1991. However, this
assumption suggests knowledge of exact production dates and storage
conditions that were not established. But UNSCOM and intelligence
community reporting about the near-wartime capabilities of Iraq
suggests that while the sarin produced was of poor quality, it had a
maximum purity of 60 per cent.
According to CIA documents, the total amount of agent modeled to have
been released at Al Muthanna was 1 kg, but, to be conservative, the
amount released was assumed to be 10 kg. The reasoning given for the
low amounts discharged was the heat of the explosion. The CIA assessed
that far less agent would have been released in the Al Muthanna bunker
because, based on U.S. field-testing using simulated bunkers, heat
would build up rapidly in Iraqi bunkers made of thick reinforced
concrete ceiling and walls, thereby destroying most of the agent.
However, these bumkers were targeted using high explosives, such as
Tomahawk missiles and laser-guided and non-guided bombs, that detonate
and produce instantaneous and extreme blast forces and shock and
pressure waves, as well as heat. While the CIA analysts gave great
credibility to the heat, no consideration was given to either the blast
effects of the munitions or to the higher altitude plumes generated
with the types of munitions used.
For Muhammadiyat, DOD also provided details regarding how they derived
source term characterizations for agent released using test data from
Dugway Proving Grounds. However, the types of munitions used in the
testing and, therefore, the resulting effects are not comparable to
what munitions were actually used and their effects. At Dugway Proving
Grounds, small explosive charges were placed on boxed rockets; at
Muhammadiyat, the munitions were targeted using multiple high-explosive
bombs. Agent purity at Muhammadiyat was estimated at 15 percent.
The Plume Height Was Underestimated:
Plume heights from the explosions could be significantly higher than
the plume height assumptions provided for in the modeling of Khamisiyah
and other Iraqi chemical warfare sites. The plume height data the CIA
provided for the demolitions at the Khamisiyah pit was 0-100 meters.
However, neither the DOD nor the CIA conducted testing to establish
plume heights associated with the bombings of Al Muthanna,
Muhammadiyat, or Ukhaydir. DOD modelers involved with the modeling
efforts told us that they did not calculate the plume height or any of
the other heat or blast effects associated with the bombings of these
sites because DOD had provided the modelers these data. A modeling
expert from the Defense Threat Reduction Agency (DTRA) told us that DOD
data on plume height was inconsistent with other test data for the
types of facilities bombed. The modeling expert cited test studies
conducted at White Sands Proving Grounds in New Mexico, which
demonstrated plume heights would range from 300 to 400 meters in
height.
Modeling experts from LLNL who participated only in the initial
modeling at Khamisiyah also told us, citing studies, that they
questioned how the plume height was estimated. In a pre-war analysis,
LLNL projected that the smoke source cloud, immediately following the
bombing of Iraqi chemical warfare agent facilities, would be
characterized by a surface-based plume with a 54 meter (177 ft.)
horizontal radius and a height of 493 meters (1,617 ft.). A Sandia
Laboratory empirical study, performed in 1969, established a power law
formula for calculating plume heights attributable to high-explosive
detonations (see appendix II). Using this formula, an MK-84 or GBU-24
(942.6lb. of high explosives) bomb would generate a plume of 421
meters.
DOD applied the same assumptions about the height of the plume at
Khamisiyah to model other possible chemical releases at the Al
Muthanna, Muhammadiyat, and Ukhaydir sites. At Muhammadiyat, for
example, DOD established a release height of 0.5 meters (roughly half
the bomb height) for nerve agent and a release height of 1.0 meters
(roughly half of the median height of the various bomb stacks) for
blister (mustard) agent destroyed at this location. Moreover, according
to an internal DOD memo, an initial cloud size of 10 meters in both
lateral and vertical directions was "arbitrarily" established. No
efforts were made by DOD to validate these estimates by analyzing video
images that were available showing some of the plume data, particularly
those taken from ground level at Khamisiyah, were used to project the
characteristics of the actual plumes.
As illustrated by figure 1, disparity in plume height source data could
result in vastly differing projections regarding how far the plume
travels and disperses, particularly during nighttime periods when a
stable (nocturnal) boundary layer emerges.
Figure 1: Boundary Layer Characteristics:
[See PDF for image]
[End of figure]
As also shown in figure 1, above the surface layer, in the stable
boundary layer, the winds often accelerate to higher speeds, in a
phenomenon that is called the low-level or nocturnal jet. At altitudes
on the order of 200 meters above the ground, winds may reach 10-30
meters per second (22-67.5 miles per hour) in the nocturnal jet. Higher
plumes than those postulated by DOD, coupled with this phenomenon,
could result in the rapid transport of chemical agents until disturbed
by turbulence or the return of the mixed layer sometime after dawn.
However, this possibility was not taken into consideration in any of
the modeling performed. Consequently, the modeling may have resulted in
underestimating the extent of plume coverage. (For a detailed
discussion of this issue, see appendix II.):
In addition, plume geometry associated with high-explosive discharges
shows that the majority of the mass of the plume is located toward the
higher altitudes, suggesting that the majority of the mass of the plume
would move to higher altitues where they might be transported by these
higher speed winds (see appendix III).
DOD Modeling Only Considered the Effects of a Single Bombing on Health:
Iraqi chemical warfare facilities were bombed on several occasions, but
DOD and CIA modeling did not reflect the cumulative effects of these
repeated bombings on the amounts of agents released and on the health
of troops. For example, there were 17 distinct coalition air strikes on
the Muhammadiyat ammunition storage depot. While modeling was requested
for the duration of 72 hours after the chemical release for Khamisiyah,
DOD used only a 24-hour duration for its modeling of the bombing of
Muhammadiyat. This was because at this site, unlike at others, DOD made
the assumption that all of the nerve agent was released at one time and
therefore modeled each air strike as if it was the only strike that
caused a release. According to DOD, each model produced a freeze frame
of the largest hazard area. The hazard area grows until it reaches its
maximum size, which the modeling suggests is about 10-12 hours after
the release.
Dugway Field-testing Did Not Realistically Simulate the Actual Bombing
Conditions:
DOD and the CIA also conducted post-war field-testing at Dugway Proving
Ground to simulate the actual bombing conditions at Khamisiyah to
derive the source term data for use in modeling. From May 1997 through
November 1999, the testing center at Dugway Proving Ground conducted
seven field-testings and two laboratory studies to obtain source term
data for use in DOD and CIA modeling of Khamisiyah. For testing and
simulation to be effective, the conditions have to be as close to the
actual event as possible. However, the testing did not realistically
simulate the conditions that existed during the demolition of 122-mm
chemical-filled rockets in Khamisiyah and is therefore of questionable
usefulness in providing inputs data for the modeling. The simulations
took place under conditions that were not comparable to those that
existed at Khamisiyah. During the field-testing, there were differences
in seasonal and meteorological conditions; in munition crate
construction material; in rocket construction, including the use of
concrete-filled pipes as rocket replacements to provide (inert) filler
to simulate larger stacks; the fewer numbers of rockets (and therefore
explosives) in the simulations, which may have suppressed a potential
chain reaction of explosions; the use of agent simulant (rather than
real agent); and soil. These differences result in multi-variable
uncertainty that cannot be resolved.
For example, the Dugway testing used a small sample of 32 rockets with
simulant-filled warheads to conduct seven field-testings: five were
single-rocket demolitions and two involved multiple-rocket
demolitions. One multiple-rocket trial demolition used nine functional
rockets plus three dummy rockets, while the other multiple-rocket trial
used 19 functional rockets and five dummy rockets. In contrast, at the
Khamisiyah pit, stacks of 122 mm rockets, estimated to total about
1,250 rockets, were detonated. Moreover, Dugway testing officials did
not know whether the 122 mm rockets used during the field-testings were
the same as those at the Khamisiyah pit. Dugway officials acknowledged
that exploding a larger number of rockets would make a significant
difference on the testing, and aerial bombing with a heavy load would
have a far greater effect than was the case with the Dugway testing.
According to DOD and CIA analysts, the type of soil and wood can have a
significant effect on the dispersion of the agent. However, a Dugway
testing official told us that evaporation characteristics from the
trials and models were uncertain. DOD and CIA estimates of the
evaporation and retention rates of the chemical agent spilled on the
soil may not be similar to what was actually evaporated from and
retained in the pit sand at Khamisiyah. This is because while Iraqi
soil was available and used in the laboratory testing, it was not used
during the field-testing. Similarly, DOD and the CIA estimates of the
amount of spilled agent that evaporated from and was retained in wooden
crates are suspect because Dugway testing officials could not obtain
actual wood from the Khamisiyah pit site for testing. The aged and
possibly damp wood at Khamisiyah would absorb less agent than the new
wood used at Dugway. DOD and CIA determined that only about 32 percent
of the agent was released and that most leaked into the soil and wood
with 18 percent of the leakage becoming part of the plume (2 percent
through aerosolization and 16 percent through evaporation).
Field-testings were also conducted at a different time of the year and
time of the day than the actual Khamisiyah pit event. According to
Dugway officials, testing was done in May and in the early morning
hours when drainage conditions prevail. The U.S. demolition of the
Khamisiyah pit took place on March 10th, in the late afternoon during
the presence of a mixing layer. Other demolitions took place during
evening and nighttime hours when the stable (nocturnal) boundary layer
emerges.
Despite the uncertainties in approximating the conditions that existed
even at Khamisiyah, DOD and the CIA used these data not only for the
Khamisiyah modeling, but also for the modeling of other sites. At all
these sites, the chemical warfare munitions would have been destroyed
by air strikes with much greater quantities of high-explosive charges
and under differing meteorological conditions.
Divergence in Results among the Models:
DOD made no effort to resolve widely divergent modeling results among
the models selected. Instead, a composite model approach was taken,
which contributed to, rather than resolved, uncertainty.
For example, the DOD panel tasked the LLNL to conduct an analysis using
DOD's MATHEW meteorological model with the ADPIC dispersion model.
During LLNL presentations to the DOD panel in November 1996 and
February 1997, the LLNL provided a 72-hour composite projection,
assuming an instantaneous release of the contents of 550 rockets
containing sarin. It shows the plume covering an area extending south-
southeast from the release point to the Persian Gulf, then turning
eastward at the Gulf coast, and then turning northeast over the Gulf
and extending northeastward across central Iran. (For a more detailed
discussion of this topic, see appendix IV.):
DOD models showed significant differences from the LLNL assessment. In
contrast to the LLNL modeling simulations, analysis done with the DOD
models--VLSTRACK with COAMPS meteorological models and HPAC/SCIPUFF
with OMEGA meteorological forecasting models--showed the plume from an
instantaneous release moving first southerly, and then turning to the
west-southwest. See appendix V for a 72-hour plume overlay of those
composite projections published by DOD.
According to the DOD panel, no effort was made to reconcile the
differences between the DOD and LLNL modeling efforts. The panel
determined that the results were so different that it would not be
possible to choose the most affected areas and which U.S. forces were
affected. Accordingly, the panel recommended that a composite of the
DOD models be used to combine the hazard areas predicted by the models.
Yet we observed that even among the models selected for use by DOD,
widely differing paths were evident (see appendix VI).
Assuming that a composite modeling effort is an appropriate
methodology, a composite projection, including the above projections
(DOD and CIA composite and LLNL), would encompass a far larger number
of forces and seriously skew the outcome of any epidemiological studies
done thus far, as shown in figure 2.
Figure 2: DOD Composite Projection and Lawrence Livermore National
Laboratory Projection:
[See PDF for image]
[End of figure]
A clear divergence exists in the predictions of the models. Further
research was conducted to determine whether there was data available
that might explain this divergence. As a result of this research, the
DOD panel concluded that the divergence in the modeling outcomes may be
explained by a line of diffluence (directional split) in the
independently modeled 10-mm wind field data near Khamisiyah during the
first 2 days of the modeling period. The precise location of this line
was critical to which way the material would be transported by the
wind. (See appendix VII for an illustration of this diffluence with
three different data sets).
In addition, DTRA officials told us that at the time of the modeling,
they conducted data-validation runs of the various models against
visible smoke plumes from the oil well fires in Kuwait; the runs showed
a definite bias, as shown in figure 3. According to DTRA, this
validation could mean that the uncertainty involved in using these
models could result in an angular shift of 10 to 50 degrees to the
west. In other words, the actual area coverd could be from 10 to 50
degrees to the east of the area indicated by the model, meaning that it
would cover a different population from the one in the model.
Figure 3: Validation Runs of Various Models:
[See PDF for image]
[End of figure]
DOD's Conclusion from the Epidemiological Studies Is Questionable:
Given that the DOD modeling was flawed, DOD's conclusion, from
epidemiological studies based on this modeling with regard to rate of
illness among exposed versus not exposed, is questionable.
Nevertheless, the results of the modeling were used as a basis for
determining the exposure classification--exposed versus not exposed to
chemical agents--of the troops in population-based epidemiological
studies. As we noted in 1997, to ascertain the causes of veterans'
illnesses, it is imperative that investigators have valid and reliable
information on exposure, especially for low-level or intermittent
exposures to chemical warfare agents.[Footnote 4] To the extent that
veterans are misclassified regarding exposure, relationships would be
obscured and conclusions would be misleading.
Misclassification of study subjects in the measurement of the variables
being compared is a well-recognized methodological problem in
epidemiological studies. Misclassification can have two types of
effects. First, if misclassification affects both comparison groups
equally (non-differential--equally in the exposed and unexposed
groups), it may water down the results so that important associations
are missed. Second, if misclassification affects one group more than
the other (differential misclassification), it may introduce bias that
obscures important associations or creates false associations.
Consequently, the study misclassification resulted in confounding--
that is, distorting--the results, making the conclusion questionable.
By combining the results from its individual modeling efforts, which
showed different areas of coverage, and ignoring the results of the
LLNL modeling, which showed much larger areas of coverage, DOD
potentially may have misclassified a large number of troops truly
exposed to chemical warfare agents in the putatively non-exposed group.
If exposure to chemical warfare agents truly caused adverse effects
resulting in increased hospitalization or death, such one-way
misclassification would tend to obscure the differences in
hospitalization or death rates by falsely increasing the rates in the
putatively non-exposed group while not affecting the rates in the
exposed group.
Based on the June 1996 plume modeling, DOD officials initially stated
that only 300 to 400 troops were exposed to chemical plumes. Based on
additional modeling, that number was revised to approximately 5000 on
September 1996; to approximately 20,000 on October 22, 1996; and to
98,910 on July 23, 1997. DOD 2000 estimates place the number exposed at
101,752. The number from the October 22, 1997 plume model served as the
basis for informing approximately 100,000 Gulf War veterans of possible
exposure. This 1997 plume model was also used as the basis of at least
two epidemiological studies that were published in peer-reviewed
scientific journals.
In 2000 DOD announced that as a result of ongoing scientific analysis,
DOD's Directorate for Deployment Health Support developed a new
computer model that changed the location of the Khamisiyah plume
footprint. The number of service members potentially exposed remained
approximately 100,000. The new 2000 model reclassified 32,627 troops as
unexposed who were previously classified as exposed and classified
35,771 troops as exposed who were previously classified as unexposed.
Given the weaknesses in DOD modeling and the inconsistency of data set-
-representing these models--given to different researchers, there can
be no confidence that the research conclusions based on these models
have any validity.
Conclusions:
In evaluating the limitations of the plume modeling, we concluded that
even under the best of the circumstances, the results from the modeling
cannot be definitive. Plume modeling can allow one to estimate what
might have happened when chemical warfare agents are released in the
environments. Mathematical equations are used to predict the activities
of an actual event, in this case, the direction and extent of the
chemical warfare agent plume. However, in order to predict precisely,
one needs to have accurate information on the source term and the
meteorological conditions. However, DOD did not have accurate
information on the source term or on meteorological conditions.
Given these modeling flaws, the DOD modeling results should not form
the basis for determining the extent of exposure of U.S. troops during
the Gulf War. The models selected were not fully developed and
validated for environmental fallout and the assumptions used to provide
the input into the models exhibited a preferential bias for a
particular and limited outcome. Yet even under these circumstances, the
models failed to provide similar conclusions. In addition, many
potential exposure events were not included. It is likely that if fully
developed and validated models and more realistic data for source term
were included in the modeling, particularly plume height and exposure
duration, the exposure footprints would be much larger and most likely
to cover most of the areas where U.S. and other coalition forces were
deployed. However, given the weaknesses in the data available for any
further analyses, any further modeling efforts on this issue would not
be any more accurate and helpful.
In particular, source term data used for modeling the release of
chemical warfare agents during the Gulf War were inadequate for any
model to provide, with the desired accuracy and confidence, a single
definitive simulation of dispersion. Several modeling experts told us
that if source term inputs into modeling assessments are not accurate,
the results of the modeling would not be reliable The development of
source term data was not empirically driven, but rather driven by the
subjective analyses of individual intelligence agencies. No empirically
driven analyses were applied to determine plume height source data from
the chemical warfare agent research, production, and storage sites
subjected to air strikes, and no empirically driven calculations were
disclosed regarding agent purity as it affected the rate of decay of
the chemical warfare agent munitions that, according to intelligence
agencies reports, were produced immediately prior to the war.
Efforts to simulate events and define the source term through testing
were unrealistic, conducted under inappropriate conditions and, in some
cases, inappropriately applied to dissimilar events. The subjective and
defective quality of much of the analyses conducted is best
demonstrated by the dynamic nature of the source data over time. That
is, repeated analyses resulted in continually changing conclusions and
source data, despite the fact that no aspect of the actual events
changed after their occurrence.
DOD completely disregarded the results from the LLNL model which
provided divergent results, which were in the DOD and CIA modeling
analysis. This occurred despite a high degree of divergence, even among
the selected DOD models. Further, the precise plume projections of the
LLNL model were excluded from DOD's composite modeling. Finally, in the
DOD and CIA composite model, divergence from individual models was
masked. Despite all of the uncertainties that emerged from DOD and CIA
modeling, the results of the modeling were used to serve as a basis for
determining the exposure status--exposed versus not exposed to chemical
agents--of the troops in population-based epidemiological studies.
However, given the weaknesses in DOD modeling and the inconsistency of
data set--representing these models--given to different researchers,
there can be no confidence that the research conclusions based on these
models have any validity.
Mr. Chairman, this concludes my statement. I will be happy to answer
any questions you or Members of the Subcommittee may have.
Contacts and Acknowledgments:
Should you or your offices have any questions concerning this report,
please contact me at (202) 512-6412 or Sushil Sharma, Ph.D., DrPH, at
(202) 512-3460. We can also be reached by e-mail at rhodesk@gao.gov and
sharmas@gao.gov. Individuals who made key contributions to this
testimony were Jason Fong and Laurel Rabin. James J. Tuite III, a GAO
consultant, provided technical expertise.
[End of section]
Appendix I: Khamisiyah Models:
On November 2, 1996, DOD requested the Institute for Defense Analysis
to convene an independent panel of experts in meteorology, physics,
chemistry, and related disciplines to review the Khamisiyah modeling
analysis done by the CIA and its contractor, the Science Applications
International Corporation. The DOD panel recommended conducting
additional analyses using several DOD and non-DOD meteorological and
dispersion models as shown in table 1.
Table 1: Meteorological and Dispersion Models Used in Modeling
Khamisiyah:
Meteorological Model: Coupled Ocean-Atmosphere Mesoscale Prediction
System (COAMPS); Developer/Sponsor: U.S. Navy; Dispersion Model: Hazard
Prediction and Assessment Capability/Second Order Closure, Integrated
Puff (HPAC/SCIPUFF); Developer/Sponsor: Defense Threat Reduction
Agency.
Meteorological Model: Mass Consistent Wind Field (MATHEW); Developer/
Sponsor: Department of Energy/Lawrence Livermore National Laboratory;
Dispersion Model: Atmospheric Dispersion by Particle-in-cell (ADPIC);
Developer/Sponsor: Department of Energy/Lawrence Livermore National
Laboratory.
Meteorological Model: Mesoscale Model, Version 5 (MM5); Developer/
Sponsor: National Center for Atmospheric Research; Dispersion Model:
Non-Uniform Simple Surface Evaporation, Version 4 (NUSSE4); Developer/
Sponsor: U.S. Army.
Meteorological Model: Naval Operational Global Atmospheric Prediction
System (NOGAPS); Developer/Sponsor: U.S. Navy; Dispersion Model: Vapor
Liquid Solid Tracking (VLSTRACK); Developer/Sponsor: U.S. Navy.
Meteorological Model: Operational Multi-scale Environment Model with
Grid Adaptivity (OMEGA); Developer/Sponsor: Defense Threat Reduction
Agency; Dispersion Model: [Empty]; Developer/Sponsor: [Empty].
Source: GAO.
[End of table]
[End of section]
Appendix II: Power Law Formula:
A Sandia Laboratory empirical study performed in 1969 established a
power law formula for calculating plume heights attributable to high-
explosive detonations. This power law formula was derived from data on
23 test shots, ranging from 140-2,242 lbs. high explosives at U.S.
Department of Energy's Nevada Test Site (National Exercise, Test, and
Training Center) and provides a cloud top height at 2 minutes after
detonation. Most of the shots were detonated during near neutral
conditions, where the clouds continued to rise after 2 minutes; data
for 5 minutes after detonation on some shots shows tops rising to
nearly double the 2-minute values. The 2-minute values better represent
the final cloud top heights during stable conditions.
This formula is represented as:
h = 76(w^1/4):
where h = height of plume in meters
and, w = weight of explosives in pounds:
Using this formula, a MK-84 or GBU-24 (942.6lb of high explosives) bomb
would generate a plume of 421 meters:
H = 76 (942.6 pounds of high explosives)^1/4
H = 76 (5.541)
H 421 meters:
Figure II.1 shows what the plume height trend line would be using the
formula to calculate plume heights, resulting from the detonation of
high explosives ranging in weight from 100 - 2,000 lbs.
Figure 4: Plume Height by Weight of Explosive:
[See PDF for image]
[End of figure]
[End of section]
Appendix III: Plume Geometries and Wind Transport:
As shown in figure III.1, plume geometry associated with high explosive
discharges shows that the majority of the mass of the plume is located
towards the higher altitudes, suggesting that the majority of the mass
of the plume would move to higher altitudes where they might be
transported by higher speed winds.
Figure 5: Examples of Various Plume Geometries:
[See PDF for image]
[End of figure]
As shown in figure 3.2, the distribution of the plume geometry may be
affected by nocturnal jets.
Figure 6: Impact of Nocturnal Jets on Plume at Higher Altitudes:
[See PDF for image]
[End of figure]
In fact, empirical studies and actual reported and observed events tend
to refute DOD and intelligence agencies' assumptions and support the
alternative assumption of transport by low-level jets. First, empirical
testing suggests that the plume heights were much higher than
postulated in the source term data. Second, no massive casualties were
claimed, reported or observed in areas immediately surrounding the
Iraqi chemical warfare research, production, and storage sites bombed
by coalition forces. Third, since many of the bombings occurred at
night, the explosive effects coupled with higher altitude plumes and
the presence of a nocturnal boundary layer capable of moving hazardous
materials hundreds of miles could easily account for this phenomenon,
as well as the reports of chemical warfare agent detections in areas
occupied by U.S. and coalition forces. Fourth, the dynamics of
advection explained above may account for the reported wartime
nighttime detections of very low-levels of chemical agents associated
with turbulence mixing the upper and lower level atmospheric layers
resulting from aircraft-related sonic booms and incoming missiles and
artillery.
[End of section]
Appendix IV: Lawrence Livermore National Laboratory Khamisiyah
Simulation:
The Department of Energy's Lawrence Livermore National Laboratory
(LLNL) Atmospheric Release Advisory Capability was tasked to conduct an
analysis using its MATHEW meteorological model with the ADPIC
dispersion model. Between 1979 and 2003, the LLNL modeling capability,
known as the Atmospheric Release Advisory Capability (ARAC), now the
National Atmospheric Release Advisory Center (NARAC), responded to more
than 100 alerts, accidents, and disasters, and supported more than
1,000 exercises. These include assessments of nuclear accidents, fires,
industrial chemical accidents, and terrorist threats.
During its presentations to the DOD panel in November 1996 and February
1997, scientists from Lawrence Livermore National Laboratory provided
plume projections based on the data provided by the panel staff. A
number of model projections were calculated and presented to the panel.
As shown in figure IV.1, the LLNL 72-hour composite projection assuming
an instantaneous release of the contents of 550 rockets containing
sarin. It shows the plume covering an area extending south-southeast
from the release point to the Persian Gulf, then turning eastward at
the Gulf Coast, and then turning northeast over the Gulf and extending
northeastward across central Iran.
Figure 7: Lawrence Livermore National Laboratory Composite Projections:
[See PDF for image]
[End of figure]
LLNL's modeling assessment shows that the 72-hour exposure due to the
instantaneous release of sarin from 550 rockets covers a large hazard
area. According to LLNL, agent concentration in excess of the dosage
amount expected to cause "minimal effects" or symptoms on individuals
covered a 2,255 square km area extending approximately 130 km south-
southeast from the release point.[Footnote 5] Dosages in excess of the
amount that would be allowed for a worker exposed to sarin in the
workplace, or the "occupational limit,[Footnote 6]" were predicted over
a 114,468 square kilometer area, including Kuwait City, an
approximately 200 kilometer-wide area across the Persian gulf, and the
higher elevations of the Zagos mountain range in Iran. The remaining
area was determined to be at the "general population limit."[Footnote
7]
[End of section]
Appendix V: DOD Model Simulations:
A 72-hour plume overlay of those composite projections published by
OSAGWI is shown in figure V.1.
Figure 8: DOD Composite Projection:
[See PDF for image]
Note: This projection includes the VLSTRAK and SCIPIFF/HPAC dispersion
models with COAMPS, MM5, and OMEGA meteorological models.
[End of figure]
[End of section]
Appendix VI: Divergence among DOD Models:
Even among the models selected for use by the DOD panel, widely
divergent directional outcomes were observed. As shown in figure VI.1,
differences can be seen among various models for hazard areas during
the first 2 days of the modeling period for Khamisiyah.
Figure 9: Figure VI.1 Divergence among Models Used in Constructing DOD
and CIA Composite Analysis:
[See PDF for image]
[End of figure]
The March 10, 1991 graphic demonstrates a 40-45 degree divergence
between the HPAC/OMEGA and the HPAC/COAMPS projections while the March
11, 1991 graphic demonstrates approximately an 80 degree divergence.
The uncertainty attributed to this divergence is not limited to the
Khamisiyah modeling. According to a modeling analyst involved with the
modeling of Al Muthanna, the weather models used, COAMPS and OMEGA,
each showed the plume going in different directions, at a 110-120
degree difference. The analyst said that COAMPS showed the plume going
in a North/Northwest direction, while OMEGA showed the plume going
South. Similar divergence among model predictions was also observed in
the modeling of Muhammadiyat, as shown in figure VI.2.
Figure 10: Divergence in DOD Models for Muhammadiyat:
[See PDF for image]
[End of figure]
[End of section]
Appendix VII: Divergence and Wind Field Models:
In figure VII.1, windfield vector divergence projections 6.0 meters
above terrain are based on observational data processed by the
Meteorological Data Interpolation Code (MEDIC) model.
Figure 11: Lawrence Livermore National Laboratory Diagnostic Wind Model
Based on Observational Data:
[See PDF for image]
[End of figure]
In figure VII.2, the Windfield vector model based on European Centre
for Medium-Range Weather Forecast (ECMWF) projections, processed by the
Meteorological Data Interpolation Code (MEDIC) model, is shown.
Figure 12: Lawrence Livermore National Laboratory Diagnostic Wind Model
Based on ECMWF Projections:
[See PDF for image]
[End of figure]
In figure VII.3, the windfield vector model is based on Coupled Ocean-
Atmosphere Mesoscale Prediction System (COAMPS) Simulations at the U.S.
Naval Research Laboratories.
Figure 13: Windfield Vector Model Based on COAMPS:
[See PDF for image]
[End of figure]
[End of section]
FOOTNOTES
[1] Observations were few because Iraq stopped reporting weather
station measurement information to the World Meteorological
Organization in 1981. As a result, data on the meteorological
conditions during the Gulf War were sparse. The only data that were
available were for the surface wind observation site, 80 to 90
kilometers away, and the upper atmospheric site, about 200 kilometers
away.
[2] The Presidential Advisory Committee on Gulf War Veterans' Illnesses
was a panel established in August 1995 to provide oversight to Gulf War
illnesses investigations.
[3] DOD had asked the Institute of Defense Analyses to set up a DOD-
funded panel to review the modeling.
[4] GAO, Gulf War Illnesses: Improved Monitoring of Clinical Progress
and Reexamination of Research Emphasis Are Needed, (GAO/NSIAD-97-163,
June 23, 1997).
[5] Minimal effects is the lowest concentration level that would be
expected to have noticeable effects on human beings.
[6] Occupational limit is about one-tenth of the minimal effects value
and is the maximum concentration level that would be allowed for a
worker who could become exposed to sarin in the course of his job
duties.
[7] The general population limit represents the limit below which any
member of the general population could be exposed (e.g., exhale) 7 days
a week, every week, for a lifetime, without experiencing any adverse
health effects.
