A Proposal to the Office of Naval Research

800 North Quincy Street

Arlington, VA 22217-5660

Attn: Dr. Ronald J. Ferek, Ph 703-696-0518, ferekr@onr.navy.mil

for

**Solar Spectral Flux, Optical Depth, Water Vapor, and Ozone
Measurements and Analyses in the ACE-Asia Spring 2001 Intensive
Experiment**

Co-Principal Investigators:

+-----------------------------------+-----------------------------------+
| Peter Pilewskie Date              | Philip B. Russell Date            |
|                                   |                                   |
| Atmospheric Physics Branch        | Atmospheric Chemistry and         |
|                                   | Dynamics Branch                   |
| Earth Science Division            |                                   |
|                                   | Earth Science Division            |
| NASA Ames Research Center,        |                                   |
| Moffett Field, CA 94035-1000      | NASA Ames Research Center,        |
|                                   | Moffett Field, CA 94035-1000      |
| Telephone: 650-604-0746. Fax:     |                                   |
| 650-604-3625                      | Telephone: 650-604-5404. Fax:     |
|                                   | 650-604-6779                      |
| ppilewskie@mail.arc.nasa.gov      |                                   |
|                                   | prussell@mail.arc.nasa.gov        |
+-----------------------------------+-----------------------------------+

Co-Investigators:

Beat Schmid, Bay Area Environmental Research Institute (Tel.
650-604-5933, <bschmid@mail.arc.nasa.gov>)

Jens Redemann, Bay Area Environmental Research Institute (Tel.
650-604-6259, jredemann@mail.arc.nasa.gov)

John M. Livingston, SRI International (Tel. 650-604-3386,
<jlivingston@mail.arc.nasa.gov>)

Research Period and Budget Requested from ONR:

[Task 1]{.underline} [Task 2]{.underline} [Total]{.underline}

November 1, 2000 -- October 31, 2001: \$94.4K \$60.0K \$154.4K

Reviewed by:

+-----------------------------------+-----------------------------------+
| Warren J. Gore, Chief Date        | R. Stephen Hipskind, Chief Date   |
|                                   |                                   |
| Atmospheric Physics Branch        | Atmospheric Chemistry and         |
|                                   | Dynamics Branch                   |
+-----------------------------------+-----------------------------------+

Authorizing Official:

Estelle P. Condon, Chief Date

Earth Science Division

NASA Ames Research Center

TABLE OF CONTENTS

[Page]{.underline}

ABSTRACT 1

1\. BACKGROUND 1

> 1.1 ACE-Asia Goals, Overall Approach, and the Spring 2001 Intensive
> Experiment 1
>
> 1.2. Results From Previous Work 3
>
> 1.2.1 Solar Spectral Flux Radiometer (SSFR) Analysis and Results 3
>
> 1.2.2 Ames Airborne Tracking Sunphotometer (AATS) Analysis and Results
> 5
>
> 1.2.3 Results from Combined SSFR and AATS Measurements and Analyses 6

2\. PROPOSED RESEARCH 7

> 2.1 Objectives 7
>
> 2.2. Proposed Tasks 7
>
> 2.2.1 ONR-Funded Task One: SSFR Measurements and Analyses 7
>
> 2.2.2 ONR-Funded Task Two: AATS-14 Measurements and Analyses 7
>
> 2.2.3 NASA-Funded Integrated Analyses 7
>
> 2.3. Schedule 8
>
> 2.4. References 8

3\. BUDGET 9

4\. STAFFING, RESPONSIBILITIES, AND VITAE 9

ILLUSTRATIONS F1

ABSTRACT

We propose to provide measurements and analyses of solar spectral fluxes
and direct beam transmissions in support of the ACE-Asia Spring 2001
Intensive Experiment. Spectral fluxes (300-1700 nm at 10 nm resolution)
will be measured by a zenith and nadir viewing Solar Spectral Flux
Radiometer (SSFR) on the CIRPAS Twin Otter. Simultaneously and on the
same aircraft, direct beam transmissions will be measured in 14 narrow
bands (354-1558 nm) by the 14-channel Ames Airborne Tracking
Sunphotometer (AATS-14). The AATS-measured beam transmissions will be
analyzed to derive aerosol and thin-cloud optical depth at 13
wavelengths, plus column water vapor overburden and, when aerosol
optical depths are small enough (\<\~0.02), ozone overburden. The data
will be used to support the overall goals of ACE-Asia, with emphasis on
determining the net solar radiative forcing of East Asian/West Pacific
aerosols, quantifying the solar spectral radiative energy budget in the
presence of elevated aerosol loading, supporting satellite algorithm
validation, and providing tests of closure with in situ measurements.

**1 BACKGROUND**

**1.1 ACE-Asia Goals, Overall Approach, and the Spring 2001 Intensive
Experiment**

The Asian Pacific Regional Aerosol Characterization Experiment
(ACE-Asia) is the fourth in a series of aerosol characterization
experiments organized by the International Global Atmospheric Chemistry
Program (IGAC). Each ACE is designed to integrate suborbital and
satellite measurements and models so as to reduce the uncertainty in
calculations of the climate forcing due to aerosol particles (Huebert et
al., 1999b). ACE-Asia focuses on aerosol outflow from Asia to the
Pacific basin troposphere because (1) Asian anthropogenic emissions and
mineral dust are very different from the environments of previous ACE
experiments, and (2) Expected increases in Asian emissions have the
potential to cause large changes in radiation budgets, cloud
microphysics, and hydrological output over the coming decades.

The goals of ACE-Asia are to determine and understand the properties and
controlling factors of the aerosol in the anthropogenically modified
atmosphere of Eastern Asia and the Northwest Pacific and to assess their
relevance for radiative forcing of climate (Huebert et al., 1999b).
ACE-Asia consists of three focused components in the 2000-2004
timeframe:

1.  In-situ and column integrated measurements at a **network of ground
    stations** will quantify the chemical, physical and radiative
    **properties of aerosols** in the ACE-Asia study area and assess
    their spatial and temporal (seasonal and inter-annual) variability
    (2000-2004).

2.  An **intensive experiment** will be used to quantify the horizontal
    and vertical distributions of **aerosol properties, the processes**
    controlling their formation, evolution and fate, and the **column
    integrated clear-sky radiative effect** of the aerosol (March
    through May, 2001).

3.  **The effect of clouds on aerosol properties and the effect of
    aerosols on cloud properties (indirect aerosol effect)** will be
    quantified in focused intensive experiments (Spring 2001 and Spring
    2002 or 2003).

This proposal addresses measurements in the Spring 2001 Intensive
Experiment (previously called the Survey and Evolution Component,
AA-SEC). The experiment (Huebert et al., 2000) has three overall
scientific objectives, with the greatest emphasis on the first two:

• [Objective 1]{.underline}. Determine the physical, chemical, and
radiative properties of the major aerosol types in the Eastern Asia and
Northwest Pacific region and investigate the relationships among these
properties.

• [Objective 2]{.underline}. Quantify the interactions between aerosols
and radiation in the Eastern Asia and Northwest Pacific region

• [Objective 3]{.underline}. Quantify the physical and chemical
processes controlling the evolution of the major aerosol types and in
particular of their physical, chemical, and radiative properties.

As stated by Huebert et al. (2000), ACE-Asia as a whole has a fourth
objective, which will depend on information gathered in the 2001
Intensive Experiment (among other sources):

• [Objective 4]{.underline}. Develop procedures to extrapolate aerosol
properties and processes from local to regional and global scales, and
assess the regional direct and indirect radiative forcing by aerosols in
the Eastern Asia and Northwest Pacific region.

Further information about ACE-Asia can be found on the Project Website
(saga.pmel.noaa.gov/aceasia/) or from members of the ACE-Asia Executive
Committee:

Barry J. Huebert, Lead Scientist, University of Hawaii, USA,
<huebert@soest.hawaii.edu>

Timothy S. Bates, NOAA/PMEL, USA, <bates@pmel.noaa.gov>

Thomas Choularton, University of Manchester, UK,
[t.choularton@umist.ac.uk](mailto:tom.choularton@nessis.mcc.ac.uk)

John Gras, CSIRO, Australia, <john.gras@dar.csiro.au>

Kimitaka Kawamura, Hokkaido University, Japan,
<kawamura@soya.lowtem.hokudai.ac.jp>

Young-Joon Kim, KJIST, Korea,
[yjkim@env.kjist.ac.kr](mailto:yjkim@env.kist.ac.kr)Mingxing Wang,
Institute of Atmospheric Physics, Beijing, China,
<wmx@lasgsgi4.iap.ac.cn>

In the Spring 2001 Intensive Experiment flight plans and ship operations
will be directed to sample regional aerosol features (e.g. dust layers,
urban and industrial plumes) under different synoptic meteorological
patterns and at various distances from shore. Quantifying aerosol direct
radiative forcing will require the integration of multiple measurement
and modeling approaches. Radiative transfer models, coupled with
chemical transport models, will be used to partition the radiative
effects of aerosols between the natural and anthropogenic components and
thus attempt to quantify aerosol direct radiative forcing. These models
must rely on accurate parameterizations of aerosol properties.
Satellites will be used to assess the temporal and spatial variability
in aerosol columnar extinction. These observations can be used to assess
the direct radiative effect of the combined natural and anthropogenic
aerosol. However, the algorithms used for these retrievals must again
rely on accurate parameterizations of aerosol properties. In-situ
measurements of aerosol chemical, physical, and radiative properties and
radiative fluxes throughout the vertical column can be used to directly
quantify the radiative effect of the combined natural and anthropogenic
aerosol and provide the parameterizations needed for satellite
retrievals and models. The combination of in-situ measurements, columnar
extinction measurements (surface-based, air and space-borne
radiometers), radiative flux measurements and models will produce an
overdetermined data set that can be used to evaluate the combined
uncertainty of the models and measurements used to assess the direct
radiative forcing of aerosols in the ACE-Asia study area.

Huebert et al., (2000) describe a plan to address these questions using
three US mobile platforms (the NCAR C-130, the CIRPAS Twin Otter, and a
NOAA ship) plus 1-2 enhanced ground stations working in coordination
with ships, aircraft, lidars, and surface sites from a variety of
nations (e.g., Japan, Korea, China, and Taiwan). The operations base
will be Iwakuni Marine Corps Air Station (MCAS), near Hiroshima in
southern Japan. Efforts will be made to coordinate some flights with the
NASA TRACE-P program, which will be focusing on photochemistry in Asian
outflow at about the same time, using measurements on the NASA DC-8 and
P-3.

As in previous ACEs, satellite data products will be used by ACE-Asia
both in realtime to plan and direct flights and for post-campaign
analyses. For example, ACE-Asia flights that study the plumes of desert
dust emanating from Asia will be guided by satellite observations that
identify locations of maximum dust concentrations and areas where
concentration gradients can most easily be studied. In flights designed
to study aerosol evolution, satellite observations of the decay of
backscatter by the continental plume will be used to identify regions
where removal mechanisms seem especially effective. As amplified in the
following sections, our proposed research will contribute to the
validation and refinement of satellite retrievals.

**1.2 Results From Previous Work**

**1.2.1 Solar Spectral Flux Radiometer (SSFR) Analysis and Results**

#### *Cloud Remote Sensing*

The SSFR is a newer version of a prototype spectroradiometer that was
first designed to infer the thermodynamic phase of clouds (Pilewskie and
Twomey, 1987; Pilewskie and Twomey, 1992). Using measurements of either
spectral reflectance or spectral transmission (defined by the observer's
viewing angle; for reflectance, π/2≤μ≤π; for transmission, 0≤μ≤π/2),
cloud phase can be determined by the signal in the atmospheric window
between 1.55 μm and 1.75 μm. Since ice is nearly four times more
absorbing than liquid water at 1.65 μm, ice spectra have lower amplitude
signal in this band. The ice spectrum also shows a shift of the peak
signal towards longer wavelength when compared to a water cloud
spectrum, following the absorption spectra of bulk liquid water and ice.

The result of applying asymptotic formulae to derive relationships
between measured transmission and the bulk absorption affords a simple
yet powerful constraint on the composition of absorbing material. These
relationships can be used not only to unambiguously discriminate between
cloud phase, but also to reveal the presence of a heretofore "unknown"
absorber. Our observations of near-infrared cloud transmission have
substantiated the premise that liquid water and ice are the dominant
absorbers in the near-infrared window bands. Similar relationships are
being employed to develop methods of inferring cloud ice/liquid water
content and enhanced water vapor path through the multiple scattering
medium of thick clouds (Pilewskie and Twomey, 1996).

# *Clear Sky Solar Radiative Energy Budget*

The first SSFR data to be extensively analyzed and compared to model
derived spectra for cloud-free conditions were obtained during the NASA
SUCCESS experiment in 1995. Comparisons between measurements and model
calculations of the spectrally resolved downwelling irradiance at the
ground showed that for cloud-free conditions there was agreement to
within instrumental and model uncertainties of 5% (Pilewskie, et al.,
1998). The greatest disagreement occurred in the 400 -700 nm band. The
integrated irradiance over the band from 400 nm to 2200 nm agreed to
within 3%. Roughly 85% of the difference between the modeled and
measured integrated irradiance occurred in the 400 to 700 nm band. The
level of agreement between measured and modeled spectra in the water
vapor absorption bands was encouraging, considering that water vapor is
the primary absorber in the atmosphere. However, we concluded that it
would be necessary to compare similar spectral data over a broader range
of atmospheric conditions to fully assess our ability to model solar
spectral irradiance.

Data acquired during the 1997 Department of Energy Atmospheric Radiation
Measurement (DOE ARM) Shortwave Intensive Operational Period (SWIOP)
shows that a discrepancy exists between models and observations in the
cloud free atmosphere and it is highly correlated with water vapor
(Pilewskie et al., 2000). The difference between modeled and measured
flux increases most rapidly in the two mid-visible bands between 442 nm
and 778 nm and the trend becomes nearly flat in the near-infrared (see
Figure 1). Over this entire spectral region the difference grows at a
rate of approximately 9 Wm^-2^ per cm of water. Relative to the energy
at the top of the atmosphere, the bias increases by about 1% per cm of
water in the two bands between 442 and 625 nm and 625 and 778 nm, with
smaller relative contributions in the other bands. The source of the
discrepancy remains undetermined because of the complex dependencies of
other variables on water vapor.

## *Principal Component Analysis*

A formal approach to any remote sensing problem is to transform the
original set of measured variables into a smaller set of
mutually-orthogonal uncorrelated variables. For SSFR spectra, the
measurement variables are irradiance (or radiance) values at many
wavelengths. While several hundred measurements comprise a single
spectrum, relatively few are independent: measurement of flux at one
wavelength is sufficient to calculate flux in other regions of the
spectrum given constituents of known absorption and scattering. The
initial step is to determine the correlation between irradiance at
different wavelengths which is then used to derive the *principal
components*, linear combinations of the original irradiance values. The
virtue of this procedure is to define the minimum number of parameters
necessary to characterize atmospheric spectral irradiance, or the
*dimensionality* of atmospheric variability. PCA can be applied to set
limits on the number of parameters that can be inverted from a spectral
data set.

Physically independent influences (in our application, different
absorbers and scatterers: condensed water, oxygen, ozone, carbon
dioxide, aerosols, etc.) do not in general produce independent
orthogonal components in the measurement (spectral) domain. PCA produces
orthogonal patterns, which of necessity are weighted combinations of the
contributions of two or more independent influences. That difficulty
faces PCA in general and has been discussed at some depth by Richman
(1986), who describes so-called rotation schemes that affect a
recombination of raw orthogonal patterns to produce patterns
(non-orthogonal) that better separate effects of physically independent
causes.

This was the general procedure followed by Rabbette and Pilewskie (2000)
in the analysis of SSFR spectra from the ARM 1997 Fall Shortwave
Intensive Operational Period (SWIOP). The input variable matrix used in
that study constituted nearly 7000 spectra (between 360 and 1000 nm)
which were acquired over a three-week period at the ARM CART site in
north central Oklahoma. The time series of the first two rotated
Principal Components (PCs) reveal strong similarities to the time series
of cloud liquid water content (97% of the explained variance) and
integrated column water vapor (2.5% of explained variance). Since the
analyzed spectra were in the shortest wavelength region of the solar
spectrum, variability associated with cloud water was due to scattering,
not absorption.

# *The Solar Radiative Energy Budget in the Cloudy Atmosphere*

The solar radiative energy budget of the cloudy atmosphere has been the
focus of considerable attention due to several recent studies which
suggested that our ability to estimate broadband radiative fluxes and,
consequently, to infer atmospheric absorption, using detailed radiative
transfer models is poor (Cess, et al., 1995; Pilewskie and Valero, 1995;
Valero et al., 1998). The recently completed Atmospheric Radiation
Measurement (ARM) Enhanced Shortwave Experiment (ARESE) was the second
major DOE field campaign dedicated to measuring the absorption of solar
radiation by clouds. Figure 2 is an example of SSFR spectra during
ARESEII and is representative of the type of data we will obtain during
the ACE-ASIA flight missions. During ARESEII the SSFR was integrated on
the Sandia National Laboratory Twin Otter in nadir and zenith viewing
ports. The blue curve is the nadir-viewing (upwelling) irradiance over
north-central Oklahoma on 20 March 2000 at 1700 GMT. Spectral
integration time is 100 ms. The red curve is the zenith-viewing
(downwelling) irradiance, also at 1700 GMT, and the green spectrum is
the difference between downwelling and upwelling irradiance, or the net
flux. During ARESE II nearly 200,000 irradiance spectra were acquired
over a variety of scenes and altitudes in the lower and middle
troposphere.

**1.2.2 Ames Airborne Tracking Sunphotometer (AATS) Analysis and
Results**

The Ames Airborne Tracking Sunphotometers (AATS-6 and AATS-14) have
previously flown on a variety of aircraft to study a wide range of
aerosol and trace gas phenomena. Among the AATS results most relevant to
ACE-Asia are those obtained in the second Aerosol Characterization
Experiment (ACE-2), where elevated layers of Sahara dust were studied
over the eastern Atlantic Ocean (Russell and Heintzenberg, 2000). Figure
3 shows an example measured by AATS-14 on the Pelican aircraft in the
Canary Islands (Schmid et al., 2000). The optical depth profiles in the
left panel were smoothed and vertically differentiated to obtain the
extinction profiles in the right panel. The extinction profiles clearly
show the presence of three distinct layers: an elevated layer of Sahara
dust, a moderately polluted marine boundary layer, and an intervening
layer that is nearly aerosol-free. Note the marked difference in
extinction wavelength-dependence in the two aerosol layers: a strong
dependence in the boundary layer (extinction profiles separated in
wavelength) and almost no dependence in the elevated dust layer
(extinction profiles overlapping except at 1558 nm). This difference
reflects the difference of aerosol size in the two layers, with
accumulation-mode particles important in the polluted boundary layer and
coarse-mode particles more important in the Sahara layer.

Figure 4 shows how the presence of elevated dust layers can affect the
accuracy of optical depths retrieved from satellite radiance
measurements. The scatter diagram in Figure 4a (Durkee et al., 2000)
compares AVHRR-retrieved aerosol optical depth (AOD) at 630 and 860 nm
with AOD measured in ACE-2 by a variety of sunphotometers on land, ship,
and aircraft. Data points with AOD\>0.25 are cases where an elevated
layer of Sahara dust was present; those with AOD\<0.25 had no Sahara
dust. For all 23 cases shown the AVHRR standard error of estimate is
0.025 for 630 nm wavelength and 0.023 for 860 nm. Note that in the
dust-containing cases (AOD\>0.25), the AVHRR-retrieved AODs are biased
low compared to sunphotometer optical depths (by amounts ranging from
0.01 to 0.08). In contrast, for the dust-free cases AVHRR-retrieved
values are biased slightly high. Figure 4b compares AOD spectra for a
case from Figure 4a where dust was present (this is also the case from
Figure 3); Figure 4c is the analogous comparison for a dust-free case
(Livingston et al., 2000; Schmid et al., 2000). These cases show clearly
the change in bias of the AVHRR retrieved values between dust-free and
dust-containing cases, especially at 860 nm. Possible reasons for this
change include differences between the wavelength-dependent single
scattering albedos and phase functions of the Sahara dust and those
assumed in the AVHRR retrieval (Durkee et al., 2000), plus the height of
the absorbing dust aerosols (e.g., Quijano et al., 2000). In ACE-Asia,
sunphotometer underflights of aerosols in different conditions (e.g.,
marine aerosols with and without Asian dust aloft) could provide
analogous tests of the validity of satellite products as a function of
condition. Vertical profile flights by the sunphotometer aircraft or a
coordinated aircraft could provide simultaneous in situ data on aerosol
physicochemical properties, helping to complete the picture.

In addition to vertical profile flights, airborne sunphotometer
measurements flown along horizontal transects near the land or ocean
surface can provide aerosol optical depth spectra useful for validating
products from simultaneous satellite overflights. This is illustrated in
Figure 5, which shows a comparison of airborne sunphotometer (AATS-6),
AVHRR, and ATSR-2 data acquired in TARFOX (Russell et al., 1999a) over
the Atlantic Ocean when the UW C-131A flew across a gradient of aerosol
optical depth between latitudes 37-39 N (Veefkind et al., 1999). The
flight path was chosen using half-hourly GOES images to locate the
aerosol gradient. Comparing Figures 5a and 5b shows that the ATSR-2
retrieval reproduces the sunphotometer-measured optical depth gradient
better than the AVHRR retrieval. Comparing 3c and 3d shows how the
ATSR-2 retrieval also matches the sunphotometer-determined Angstrom
exponent better than AVHRR. In ACE-ASIA, GOES or other realtime
satellite imagery could be used to design flight legs across the
gradient from plume core to edge during a subsequent satellite overpass
(by, e.g., EOS Terra carrying MODIS, MISR, and CERES). AATS optical
depth spectra on legs flown near the surface would provide validation
data for comparisons such as those in Figure 5.

Figure 6 shows other comparisons from TARFOX, when AATS-6 on the UW
C-131A underflew the MODIS Airborne Simulator (MAS) on the NASA ER-2
(Tanre et al., 1999). These comparisons focus on the wavelength
dependence of optical depth and illustrate how the magnitude of optical
depth affects the success of the MAS retrieval. Specifically, the good
agreement in wavelength dependence and magnitude obtained when optical
depth is relatively large (\>0.2 for λ\<1 μm) degraded when optical
depth decreased below \~0.05 (causing MAS-measured radiance from the
aerosol to decrease relative to radiance from the ocean surface).
Establishing such limits and uncertainties is a major reason for
validation studies. In ACE-Asia they could be conducted for a variety of
aerosol types and conditions, over different types of land surfaces
(e.g., densely vs. sparsely vegetated), glint-free and glinting swaths
of ocean, and on transects spanning land and ocean.

**1.2.3 Results from Combined SSFR and AATS Measurements and Analyses**

In Summer 2000 the SSFR and the 6-channel AATS (AATS-6) flew together on
the Navajo aircraft in the Puerto Rico Dust Experiment (PRIDE). The SSFR
and AATS-6 operated very successfully, acquiring large data sets on the
radiative effects of Saharan dust, marine aerosols, and clouds over the
Caribbean Sea. Analyses of the PRIDE SSFR and AATS-6 data sets are
currently in progress; early results will be presented at the PRIDE
special session of the Fall 2000 AGU Meeting. This section shows some
examples of these early results.

## *Vertical Profiles of Multiwavelength Optical Depth and Extinction for PRIDE Aerosols* 

Figure 11 shows an example of results from AATS-6 measurements acquired
in PRIDE on 21 July 2000, when the Navajo flew a profile that extended
from near the sea surface to \~5.7 km asl. The optical depth profiles in
the left panel are derived from AATS-6 measurements of solar beam
transmission. These optical depth profiles were smoothed and vertically
differentiated to obtain the extinction profiles in the right panel. The
extinction profiles clearly show the presence of a layer of increased
aerosol extinction at altitudes \~2-4.6 km asl, above the marine
boundary layer. Other measurements made simultaneously on the Navajo
show that this elevated layer contained high concentrations of mineral
dust. Trajectory analyses showed that the dust had been transported
across the Atlantic from the Sahara Desert. Note that extinction in the
elevated Sahara dust layer is nearly independent of wavelength over the
range 380-1021 nm. This wavelength-independence reflects the importance
of coarse-mode particles in the Sahara layer. Within the marine boundary
layer the data suggest a change in wavelength dependence, especially at
1021 nm. However, this change is within the uncertainty of the
measurements, and we do not consider it significant without further
study.

## *Solar Radiative Forcing by Dust Aerosol*

The Navajo flight on 15 July 2000 in PRIDE included a descent with seven
horizontal legs of approximately five to ten minutes duration, several
of which were in a classic Saharan air layer. Simultaneous SSFR and
AATS-6 measurements of solar spectral flux and optical depth were made
on each leg, providing an excellent opportunity to study the radiative
forcing due to Saharan dust over the Caribbean. We computed average
downwelling and upwelling spectral fluxes on each of the seven legs to
determine the net spectral flux (downwelling minus upwelling) at each
level. Results are shown in Figure 12. We determined from time series
data and from simultaneous AATS-6 data (not shown here) that significant
portions of some the legs were contaminated by overlying cirrus.
However, little or no cirrus contamination was present in the data from
legs three, four, and five, which were right in the heart of the dust
layer. The difference in net flux between any two of these levels is the
absorption (alternatively, flux divergence) of the intervening layer.
Layer absorption spectra obtained this way are shown in Figure 13.
Absorption by water vapor is significant in the near-infrared. However,
there is a monotonic increase in absorption (with decreasing wavelength)
at wavelengths less than 600 nm. This is consistent with the known
optical properties of Saharan dust: the absorption peak in the
near-ultraviolet is responsible for its reddish color.

The AATS-6 measurements (not shown here) gave mid-visible dust optical
thickness (DOT~midvis~) values of approximately 0.15 for each layer and
0.3 for the total dust layer. The integrated absorption from 300-600 nm
is approximately 5 W m^-2^ for each layer, or 10 W m^-2^ for the total
(DOT~midvis~=0.3), so the measured absorption by dust aerosol is
approximately 33 W m^-2^ per unit optical depth.

2 PROPOSED RESEARCH

**2.1 Objectives**

The objectives of the proposed research are to:

(1) Improve understanding of dust, other aerosol, and water vapor
    effects on radiative transfer, radiation budgets and climate in the
    East Asian/West Pacific region, and

\(2\) Test and improve the ability of satellite remote sensors (such as
MODIS, MISR, CERES, TOMS, AVHRR) to measure these constituents and their
radiative effects.

**2.2 Proposed Tasks**

**2.2.1 ONR-Funded Task One: SSFR Measurements and Analyses**

The NASA Ames Radiation group will deploy a Solar Spectral Flux
Radiometer (SSFR) on the CIRPAS Twin Otter during the ACE-Asia intensive
experiment in March-April, 2001. The SSFR has zenith and nadir viewing
light collectors for measuring solar spectral upwelling and downwelling
irradiance from 300 to 1700 nm at 10 nm resolution. This data will be
used to determine the net solar radiative forcing of dust and other
aerosols, to quantify the solar spectral radiative energy budget in the
presence of elevated aerosol loading, and to support satellite algorithm
validation.

The SSFR is calibrated for wavelength, absolute power, and angular
response at the NASA Ames Research Center. Some of this work is done in
conjunction with the Ames Airborne Sensors Facility which takes part in
round robin calibration comparisons with NIST and the University of
Arizona. The Airborne Sensors Facility is also responsible for
calibrating flight simulation sensors, such as the MODIS Airborne
Simulator (MAS), and the use of identical standards will allow us to
trace SSFR calibrations to MAS.

We will meet all data archival schedules; we anticipate three levels of
data release.

**2.2.2 ONR-Funded Task Two: AATS-14 Measurements and Analyses**

For the funding requested in this proposal (Section 3) the NASA Ames
Sunphotometer/Satellite group will perform the following subtasks: (a)
Integrate the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14)
on the CIRPAS Twin Otter. (b) Calibrate AATS-14 before and after the
Spring 2001 experiment. (c) Provide continuous realtime measurements of
aerosol and thin cloud optical depth spectra and water vapor column
contents during the Spring 2001 experiment flights. (d) Use these data
in flight direction and planning.

**2.2.3 NASA-Funded Integrated Analyses**

In addition to ONR funded Tasks One and Two, we plan to perform the
following subtasks using NASA funding: (e) Compare AATS-14 results to
those of the satellite sensors listed above (as, e.g., in Figures 4-6);
in cases of disagreement, investigate causes and retrieval algorithm
improvements. (f) For aircraft profiles derive profiles of aerosol
extinction spectra and water vapor density by differentiating optical
depth and column water vapor profiles (as exemplified by Figures 3 and
7). (g) Combine these data with those from the SSFR and conduct new
analyses of aerosol radiative forcing sensitivity, single scattering
albedo, and the solar spectral radiative energy budget (as exemplified
by Figure 8). (h) Derive aerosol size distributions from optical depth
and extinction spectra (as exemplified by Figure 9). (i) Combine data
with in situ measurements (e.g., the Twin Otter measurements of size
distribution, scattering, and/or absorption) to provide tests of closure
and integrated assessments of aerosol and trace gas radiative effects.
An example of such a closure test is shown in Figure 10 (Schmid et al.,
2000). (j) When midvisible aerosol optical depths are sufficiently small
(\<\~0.02, e.g., above major aerosol layers), derive ozone overburdens;
compare these results to satellite-retrieved values and, if appropriate,
assess their potential impact on tropospheric solar energy budgets
and/or photodissociation rates. We will report results of the analyses
in joint publications with collaborating investigators.

**2.3 Schedule**

1/01: Final pre-flight SSFR and AATS-14 calibration

2/01: Integration and test flights of SSFR and AATS-14 on CIRPAS Twin
Otter

3-4/01: Field deployment

5/01: post-flight calibrations

11/01: first data release

3/02: second data release

5/02: final data release

**2.4 References**

Cess, R.D., et al., Absorption of solar radiation by the earth's
surface: Observations versus models. *Science*, **267**, 496 (1995).

Durkee, P. A., Nielsen, K. E., Russell, P. B., Schmid, B., Livingston,
J. M., Collins, D., Flagan, R. C., Seinfeld, H. H., Noone, K. J.,
Ostrom, E., Gassó, S., Hegg, D., Bates, T. S., Quinn, P. K., and
Russell, L. M. this issue. Regional aerosol properties from satellite
observation: ACE-1, TARFOX and ACE-2 results. *Tellus B* 52, 484-497,
2000.

Huebert, B., T. Bates, J. Seinfeld, and J. Merrill, ACE-Asia Survey and
Evolution Component (AA-SEC) NSF Large Field Program Scientific
Overview, omnibus proposal submitted to U.S. National Science
Foundation, 22 July 1999a. Available at
<http://saga.pmel.noaa.gov/aceasia/si_nsf/index.html>.

Huebert, B., et al., ACE-Asia Project Prospectus, 30 December 1999b.
Available at
[[http://saga.pmel.noaa.gov/aceasia/prospectus2000/]{.underline}](http://saga.pmel.noaa.gov/aceasia/si_nsf/index.html).

Huebert, B., T. Bates, et al., ACE-Asia Spring 2001 Intensive Experiment
Science and Implementation Plan, Draft, September 2000, available from
the authors.

Livingston, J. M., Kapustin, V. N., Schmid, B., Russell, P. B., Quinn,
P. K., Timothy, S. B., Philip, A. D., and Freudenthaler, V. this issue.
Shipboard sunphotometer measurements of aerosol optical depth spectra
and columnar water vapor during ACE-2. *Tellus B 52*, 594-619, 2000.

Pilewskie, P., M. Rabbette, R. Bergstrom, J. Marquez, B. Schmid, and
P.B. Russell, The discrepancy between measured and modeled downwelling
solar irradiance at the ground: Dependence on water vapor. *Geophys.
Res. Lett.* **25**, 137 (2000).

Pilewskie, P. and S. Twomey, Cloud properties derived from surface-based
near-infrared spectral transmission**.** *IRS \'96: Current Problems in
Atmospheric Radiation*, A. Deepak Publishing, Fairbanks, Alaska (1996).

Pilewskie, P. and F.P.J. Valero, Direct observation of excess solar
absorption by clouds, *Science*, **267**, 1626 (1995).

Pilewskie, P., and S. Twomey, Optical remote sensing of ice in clouds.
*J. of Wea. Modif.*, **24**, 80, (1992).

Pilewskie, P. and S. Twomey, Discrimination of ice from water in clouds
by optical remote sensing. *Atmos. Research*, **21**, 113 (1987).

Pilewskie, P., and S. Twomey, Cloud phase discrimination by reflectance
measurements near 1.6 and 2.2 m. *J. Atmos. Sci.*, **44**, 3419 (1987).

Quijano, A.L., I.N. Sokolik, and O.B. Toon, Influence of the aerosol
vertical distribution on the retrievals of aerosol optical depth from
satellite radiance measurements,*Geophys. Res. Lett.,* 21, 3457-3460,
2000.

Rabbette , M. and P. Pilewskie, Multivariate analysis of solar spectral
irradiance measurements. *J. Geophys. Res*. In press (2000).

Richman, M. B., 1986: Rotation of principal components. *J. Clim*,
**6**, 293-335.

Reid, J., Preliminary Mission Plan for a Puerto Rico Dust Experiment
(PRIDE) for Summer 2000. Available from the author, SPAWARSYSCEN SAN
DIEGO D883, 49170 Propagation Path, San Diego, CA 92152-7385, email:
<jreid@spawar.navy.mil>, http://www.spawar.navy.mil

Russell, P. B., and J. Heintzenberg, An overview of the ACE-2 Clear Sky
Column Closure Experiment (CLEARCOLUMN), *Tellus B 52*, 463-483, 2000.

Russell, P. B., P. V. Hobbs, and L. L. Stowe, Aerosol properties and
radiative effects in the United States east coast haze plume: An
overview of the Tropospheric Aerosol Radiative Forcing Observational
Experiment (TARFOX), *J. Geophys. Res., 104*, 2213-2222, 1999a.

Russell, P. B., J. M. Livingston, P. Hignett, S. Kinne, J. Wong, and P.
V. Hobbs, Aerosol-induced radiative flux changes off the United States
Mid-Atlantic coast: Comparison of values calculated from sunphotometer
and in situ data with those measured by airborne pyranometer, *J.
Geophys. Res., 104*, 2289-2307, 1999b.

Schmid, B., Livingston, J. M., Russell, P. B., Durkee, P. A., Collins,
D. R., Flagan, R. C., Seinfeld, J. H., Gasso, S., Hegg, D. A., Ostrom,
E., Noone, K. J., Welton, E. J., Voss, K., Gordon, H. R., Formenti, P.,
and Andreae, M. O.. Clear sky closure studies of lower tropospheric
aerosol and water vapor during ACE-2 using airborne sunphotometer,
airborne in-situ, space-borne, and ground-based measurements. *Tellus*
*B* *52*, 568-593, 2000.

Tanre, D., L. A. Remer, Y. J. Kaufman, S. Mattoo, P. V. Hobbs, J. M.
Livingston, P. B. Russell, and A. Smirnov, Retrieval of aerosol optical
thickness and size distribution over ocean from the MODIS airborne
simulator during TARFOX, *J. Geophys. Res., 104*, 2261-2278, 1999.

Valero, F.P.J., R.D. Cess, M. Zhang, S.K. Pope, A. Bucholtz, B. Bush,
and J. Vitko, Jr., Absorption of solar radiation by the atmosphere:
interpretations of collocated aircraft measurements. *J. Geophys. Res*.,
**102**, 29,917-29,927 (1997).

Veefkind, J. P., G. de Leeuw, P. A. Durkee, P. B. Russell, P. V. Hobbs,
and J. M. Livingston, Aerosol optical depth retrieval using ATSR-2 and
AVHRR data during TARFOX, *J. Geophys. Res., 104*, 2253-2260, 1999.

![](media/image1.pct)

**4. STAFFING, RESPONSIBILITIES, AND VITAE**

Drs. Peter Pilewskie and Philip B. Russell will be Co-Principal
Investigators. Dr. Pilewskie will be responsible for the SSFR
measurements and analyses; Dr. Russell will be responsible for the
AATS-14 measurements and analyses. Drs. Pilewskie and Russell will
collaborate on analyses that combine SSFR and AATS-14 measurements, as
well as on flight planning for such measurements. They will be
responsible for the completion of their tasks within budget and
schedule. Drs. Beat Schmid and Jens Redemann and Mr. John Livingston
will participate in AATS-14 preparation, calibrations, airborne
measurements, data analyses, and publications. Ames will furnish
additional engineering and technical personnel necessary to maintain,
operate, and repair the instrumentation before, during, and after the
calibrations and field measurements.

**(a) Peter Pilewskie**

**Abbreviated Curriculum Vitae**

**Education:**

B.S., Meteorology, Pennsylvania State University, 1983

M.S., Atmospheric Science, University of Arizona, 1986

Ph.D., Atmospheric Science, University of Arizona, 1989

**Professional Experience:**

Radiation Group Leader, Atmospheric Physics Branch, NASA Ames Research
Center, 1994-present

Research Scientist, Atmospheric Physics Branch, NASA Ames Research
Center, 1989-1994

Research Assistant, Institute of Atmospheric Physics, University of
Arizona, 1983-1989

**Professional Activities:**

Member, Atmospheric Radiation Measurement (ARM) Enhanced Shortwave
Experiment (ARESE) II Science Team

Member, Solar Radiation and Climate Experiment (SORCE), 1999-present

Member, Triana Science Team, 1998-present

Member, Global Aerosol Climatology Program (GACP), 1998-present

Member, Atmospheric Radiation Measurement Program (ARM) Science Team,
1997-present

Member, International Global Atmospheric Chemistry (IGAC), Focus on
Atmospheric Aerosols, Direct Aerosol Radiative Forcing Activity,
1995-present

Member, First International Satellite Cloud Climatology Program (ISCCP)
Regional Experiment, Phase III (FIRE III) Science Team, 1994-present

# Science Team Leader, International Global Aerosol Program (IGAP), Radiative Effects of Aerosols, 1993

**Professional Honors:**

NASA Exceptional Scientific Achievement Medal, 1997

NASA Group Achievement Award, FIRE Phase II Science and Operations Team,
1997

NASA Ames Honor Award, Scientist, 1995

**Selected Publications:**

Pilewskie, P., M. Rabbette, R. Bergstrom, J. Marquez, B. Schmid, and
P.B. Russell, The discrepancy between measured and modeled downwelling
solar irradiance at the ground: Dependence on water vapor. *Geophys.
Res. Lett.* **25**, 137(2000).

Rabbette , M. and P. Pilewskie, Multivariate analysis of solar spectral
irradiance measurements. *J. Geophys. Res*. In press (2000).

Curry, J.A., P.V. Hobbs, M.D. King, D.A. Randall, P. Minnis, G.A. Isaac,
J.O. Pinto, T. Uttal, A. Bucholtz, D.G. Cripe, H. Gerber, C.W. Fairall,
T.J. Garrett, J. Hudson, J.M. Intrieri, C. Jakob, T. Jensen, P. Lawson,
D. Marcotte, L. Nguyen, P. Pilewskie, A. Rangno, D.C. Rogers, K.B.
Strawbridge, F.P.J. Valero, A.G. Williams, and D. Wyliep, FIRE Arctic
Clouds Experiment, *Bulletin of the American Meteorological Society,*
**81**, 5 (2000).

Pilewskie, P., A.F.H. Goetz, D.A. Beal, R.W. Bergstrom, and P. Mariani,
Observations of the spectral distribution of solar irradiance at the
ground during SUCCESS, *Geophys. Res. Lett.* **25**, 1141 (1998).

Heymsfield, J.A., G.M. McFarquhar, W.D. Collins, J.A. Goldstein, F.P.J.
Valero, W. Hart, and P. Pilewskie, Cloud properties leading to highly
reflective tropical cirrus: interpretations from CEPEX, TOGA COARE, and
Kwajalein, Marshall Islands, *J. Geophys. Res.*, **103**, 8805 (1998).

Valero, F.P.J., W. Collins , P. Pilewskie, A. Bucholtz, and P. Flatau,
Direct observations of the super greenhouse effect over the equatorial
Pacific, *Science,* **275***,* 1773 (1997).

Dong, X., T.P. Ackerman, E.E. Clothiaux, P. Pilewskie and Y. Han,
Microphysical and Radiative Properties of Boundary Layer Stratiform
Clouds Deduced from Ground-Based Measurements, *J. Geophy. Res*.,
**102**, 23829 (1997).

Pilewskie, P. and F.P.J. Valero, *Response to*: How much solar radiation
do clouds absorb?, *Science*, **271**, 1134 (1996).

Lubin, D., J.P. Chen, P. Pilewskie, V. Ramanathan, and F.P.J. Valero,
Microphysical examination of excess cloud absorption in the tropical
atmosphere, *J. Geophys. Res.*, **101**, 16961 (1996).

Westphal, D. L., S. Kinne, P. Pilewskie, J. M. Alvarez, P. Minnis, D.
F.Young, S. G. Benjamin, W. L. Eberhard, R. A. Kropfli, S. Y. Matrosov,
J. B. Snider, T. A. Uttal, A. J. Heymsfield, G. G. Mace, S. H. Melfi, D.
O\'C. Starr, and J. J. Soden, Initialization and validation of a
simulation of cirrus using FIRE-II data. *J. Atmos. Sci*., **53**, 3397
(1996).

Collins, W.D., F.P.J. Valero, P. Flatau, D. Lubin, H. Grassl, P.
Pilewskie, and J. Spinhirne, Radiative effects of convection in the
tropical Pacific, *Journal of Climate,* **101**, 14999 (1996).

Clarke, A.D., J.N. Porter, F.P.J. Valero, and P. Pilewskie, Vertical
profiles, aerosol microphysics and optical closure during ASTEX:
measured and modeled column optical properties, *J. Geophys. Res.*,
**101**, 4443 (1996)

Pilewskie, P. and F.P.J. Valero, Direct observation of excess solar
absorption by clouds, *Science*, **267**, 1626 (1995).

Sokolik I.N., F.P.J. Valero, and P. Pilewskie, Spatial and temporal
variations of the radiative characteristics of the plume from the Kuwait
oil fires, submitted to *Biomass burning and Global Climate Change*,
Levine J.S., Ed., MIT Press, Cambridge, MA (1995)

Valero, F.P.J., S. Platnick, S. Kinne, P. Pilewskie, and A. Bucholtz,
Airborne brightness temperature measurements of the polar winter
troposphere as part of the Airborne Arctic Stratospheric Experiment II
and the effect of brightness temperature variations on the diabatic
heating in the lower stratosphere, *Geophys. Res. Lett.*, **20**, 2575
(1993).

Pilewskie, P., F.P.J. Valero, Optical depths and haze particle sizes
during AGASP III. *Atmos. Environment*, **27A**, 2895 (1993).

Russell, P.B., J.M. Livingston, E.G Dutton, R.F Pueschel, J.A. Reagan,
T.E DeFoor, M.A. Box, D. Allen, P. Pilewskie, B.M. Herman, S.A. Kinne,
and D.J. Hoffmann, Pinatubo and pre-Pinatubo optical depth spectra:
Mauna Loa measurements, comparisons, inferred particle size
distributions, radiative effects, and relationship to lidar data. *J.
Geophys. Res.*, **98**, 22969 (1993).

Valero, F.P.J. and P. Pilewskie, Latitudinal survey of spectral optical
depths of the Pinatubo volcanic cloud derived particle sizes, columnar
mass loadings, and effects on planetary albedo, *Geophys. Res. Lett.*,
**19,** 163 (1992).

Pilewskie, P., F.P.J. Valero, Radiative effects of the smoke from the
Kuwait oil fires. *J. Geophys. Res.*, **97**, 14541 (1992).

Pilewskie, P., and S. Twomey, Optical remote sensing of ice in clouds.
*J. of Wea. Modif.*, **24**, 80 (1992).

Pilewskie, P. and S. Twomey, Discrimination of ice from water in clouds
by optical remote sensing. *Atmos. Research*, **21**, 113 (1987).

Pilewskie, P., and S. Twomey, Cloud phase discrimination by reflectance
measurements near 1.6 and 2.2 μm. *J. Atmos. Sci.*, **44**, 3419 (1987).

Reagan, J.A., P.A. Pilewskie, I.C. Scott-Fleming, and B.M. Herman,
Extrapolation of earth-based solar irradiance measurements to
exoatmospheric levels for broad-band and selected absorption-band
observations. *IEEE Trans. on Geosci. Remote Sensing*, **GE-25**, 647
(1987).

**(b) Philip B. Russell**

**Abbreviated Curriculum Vitae**

B.A., Physics, Wesleyan University (1965, Magna cum Laude; Highest
Honors). M.S. and Ph.D., Physics, Stanford University (1967 and 1971,
Atomic Energy Commission Fellow). M.S., Management, Stanford University
(1990, NASA Sloan Fellow).

Postdoctoral Appointee, National Center for Atmospheric Research
(1971-72, at University of Chicago and NCAR). Physicist to Senior
Physicist, Atmospheric Science Center, SRI International (1972-82).
Chief, Atmospheric Experiments Branch (1982-89), Acting Chief, Earth
System Science Division (1988-89), Chief, Atmospheric Chemistry and
Dynamics Branch (1989-95), Research Scientist (1995-present), NASA Ames
Research Center.

Currently, Member, Science Teams for NASA's Earth Observing System
Inter-Disciplinary Science (EOS-IDS), Global Aerosol Climatology Project
(GACP) and the satellite sensors SAGE II and SAGE III.

Previously, NASA Ames Associate Fellow (1995-96, awarded for excellence
in atmospheric research).

Previously, Co-coordinator for the CLEARCOLUMN component of the Second
Aerosol Characterization Experiment (ACE-2) of the International Global
Atmospheric Chemistry (IGAC) Project. Coordinator for IGAC's
Tropospheric Aerosol Radiative Forcing Observational Experiment
(TARFOX).

Previously, Editor (1993, 1996) and Editor-in-Chief (1994-95),
*Geophysical Research Letters*; Chair, American Meteorological Society
International Committee on Laser Atmospheric Studies (1979-82, Member,
1978-82). Member, National Research Council Committee on Army Basic
Research (1979-81). Member, American Meteorological Society Committee on
Radiation Energy (1979-81).

Previously, Project Scientist, Small High-Altitude Science Aircraft
(SHASA) Project to develop the Perseus A Remotely Piloted Aircraft (RPA,
1992-94). Member, Science/Aeronautics Seam Team of NASA Ames
Reorganization Team (1994). Member, Ad Hoc Committee on the NASA
Environmental Research Aircraft and Sensor Technology (ERAST) Program
(1993-4). Member, NASA Red Team on Remote Sensing and Environmental
Monitoring of Planet Earth (1992-3). Leader, NASA Ames Earth Science
Advanced Aircraft (ESAA) Team (1990-94). Member, National Aero-Space
Plane (NASP) Committee on Natural Environment (1988-94).

NASA Exceptional Service Medal (1988, for managing
Stratosphere-Troposphere Exchange Project). NASA Space Act Award (1989,
for invention of Airborne Autotracking Sunphotometer). Member, Phi Beta
Kappa and Sigma Xi.

**SELECTED PUBLICATIONS (from 89 peer-reviewed papers)**

Russell, P. B., and J. Heintzenberg, An overview of the ACE-2 Clear Sky
Column Closure Experiment (CLEARCOLUMN), *Tellus B 52*, 463-483, 2000.

Bergstrom, R. W., and P. B. Russell, Estimation of aerosol radiative
effects over the mid-latitude North Atlantic region from satellite and
in situ measurements. *Geophys. Res. Lett., 26*, 1731-1734, 1999.

Russell, P. B., P. V. Hobbs, and L. L. Stowe, Aerosol properties and
radiative effects in the United States Mid-Atlantic haze plume: An
overview of the Tropospheric Aerosol Radiative Forcing Observational
Experiment (TARFOX), *J. Geophys. Res*., *104*, 2213-2222, 1999.

Russell, P. B., et al., Aerosol-induced radiative flux changes off the
United States Mid-Atlantic coast: Comparison of values calculated from
sunphotometer and in situ data with those measured by airborne
pyranometer, *J. Geophys. Res.,* 104, 2289-2307, 1999.

Russell, P. B., S. Kinne and R. Bergstrom, Aerosol climate effects:
Local radiative forcing and column closure experiments, *J. Geophys.
Res.,* *102*, 9397-9407, 1997.

Russell, P. B., et al. Global to microscale evolution of the Pinatubo
volcanic aerosol, derived from diverse measurements and analyses, *J.
Geophys. Res.*, *101*, 18,745-18,763, 1996.

Russell, P.B., et al., Post-Pinatubo optical depth spectra vs. latitude
and vortex structure: Airborne tracking sunphotometer measurements in
AASE II, *Geophys. Res. Lett.*, *20*, 2571-2574, 1993.

Russell, P.B., et al, Satellite and correlative measurements of the
stratospheric aerosol: I. An optical model for data conversions, *J.
Atmos. Sci.,* *38*, 1270-1294, 1981.

**(c) Beat Schmid**

**Abbreviated Curriculum Vitae**

### Bay Area Environmental Research Institute

3430 Noriega Street

San Francisco, CA 94122

# Education

  -------------------- --------- ------ -------------------------------------------
  M.S. (Lizentiat)               1991   Institute of Applied Physics, University of
                                        Bern, Switzerland

  Ph.D.                          1995   Institute of Applied Physics, University of
                                        Bern, Switzerland

  Postdoctoral         1995-97          Institute of Applied Physics, University of
  Fellowship                            Bern, Switzerland
  -------------------- --------- ------ -------------------------------------------

# Professional Experience

[Bay Area Environmental Research Institute]{.underline}, San Francisco,
CA (1997-Present)

-Senior Research Scientist

[University of Arizona]{.underline}, Tucson, AZ (Oct. 1995 -Jan. 1996)

-Visiting Scientist

::: Definition-Term
[University of Bern]{.underline}, Switzerland (1989-1997)
:::

-Research Assistant (1989-1995)

-Postdoctoral Researcher (1995-1997)

# Scientific Contributions

-   7 years of leading studies in ground-based and airborne sun
    photometry: instrument design and calibration, development and
    validation of algorithms to retrieve aerosol optical depth and size
    distribution, H~2~O and O~3~.

-   Participate with the NASA Ames Airborne Sun photometers in ACE-2
    (North Atlantic Regional Aerosol Characterization Experiment, 1997,
    Tenerife). Extensive comparison of results (closure studies) with
    other techniques: lidar, optical particle counters, nephelometers,
    and satellites.

-   Participate with the NASA Ames Airborne Sun photometer in
    SAFARI-2000 (Southern African Regional Science Initiative).

-   Participate with the NASA Ames Airborne Sun photometers in the DOE
    Atmospheric Radiation Measurement (ARM) program integrated fall 1997
    and 2000 intensive observation periods (IOP) in Oklahoma. Appointed
    to lead sun photometer intercomparison. Extensive comparison of
    water vapor results with radiosondes, microwave radiometers, lidar,
    and Global Positioning System.

-   Test of candidate methods for SAGE 3 satellite ozone/aerosol
    separation using airborne sunphotometer data.

-   Application of NOAA/AVHRR satellite data to monitor vegetation
    growth in Switzerland

# Scientific Societies/Committees

-American Geophysical Union

-American Meteorological Society

# Publications

**2000:**

**Schmid, B**., J. M. Livingston, P. B. Russell, P. A. Durkee, H. H.
Jonsson, D. R. Collins, R. C. Flagan, J. H. Seinfeld, S. Gassó, D. A.
Hegg, E. Öström, K. J. Noone, E. J. Welton, K. J. Voss, H. R. Gordon, P.
Formenti, and M. O. Andreae, Clear sky closure studies of lower
tropospheric aerosol and water vapor during ACE 2 using airborne
sunphotometer, airborne in-situ, space-borne, and ground-based
measurements, *Tellus*, B 52, 568-593, 2000.

Pilewskie P., M. Rabette, R. Bergstrom, J. Marquez, **B. Schmid**, and
P. B. Russell: The Discrepancy Between Measured and Modeled Downwelling
Solar Irradiance at the Ground: Dependence on Water Vapor. *Geophys.
Res. Lett*., *27*(1),137-140, 2000.

Ferrare, R., S. Ismail, E. Browell, V. Brackett, M. Clayton, S. Kooi, S.
H. Melfi, D. Whiteman, G. Schwemmer, K. Evans, P. Russell, J.
Livingston, **B. Schmid**, B. Holben, L. Remer, A. Smirnov, P. Hobbs.
Comparisons of aerosol optical properties and water vapor among ground
and airborne lidars and sun photometers during TARFOX. *J. Geophys.
Res*., *105*(D8), 9917-9933, 2000.

Redemann, J., R. P. Turco, K. N. Liou, P. B. Russell, R. W. Bergstrom,
**B. Schmid**, J. M. Livingston, P. V. Hobbs, W. S. Hartley, S. Ismail,
R. A Ferrare, E. V. Browell, Retrieving the Vertical Structure of the
Effective Aerosol Complex Index of Refraction From a Combination of
Aerosol In Situ and Remote Sensing Measurements During TARFOX. *J.
Geophys. Res.*, *105*(D8), 9949-9970, 2000*.*

Collins, D. R., H. H. Jonsson, J. H. Seinfeld, R.C. Flagan, S. Gassó, D.
A. Hegg, **B.** **Schmid**, P. B. Russell, J. M. Livingston, E. Öström,
K. J. Noone, L. M. Russell, and J. P. Putaud, In situ aerosol size
distributions and clear column radiative closure during ACE-2. *Tellus*,
B 52, 498-525, 2000.

Durkee, P. A., K. E. Nielsen, P. J. Smith, P. B. Russell, **B.**
**Schmid**, J. M. Livingston, B. N. Holben, D. R. Collins, R. C. Flagan,
J. H. Seinfeld, K. J. Noone, E. Öström, S. Gassó, D. A. Hegg, L. M.
Russell, T. S. Bates, and P. K. Quinn. Regional aerosol properties from
satellite observations: ACE-1, TARFOX and ACE-2 results. *Tellus,* B 52,
484-497, 2000.

Gassó, S., D. A. Hegg, K. J. Noone, D. S. Covert, **B.** **Schmid**, P.
B. Russell, J. M. Livingston, P. A. Durkee, and H. H. Jonsson, Influence
of humidity on the aerosol scattering coefficient and its effect on the
upwelling radiance during ACE2. *Tellus,* B 52, 546-567, 2000.

Livingston, J. M., V. Kapustin, **B. Schmid**, P. B. Russell, P. K.
Quinn, T. S. Bates, P. A. Durkee, P. J. Smith, V. Freudenthaler, D. S.
Covert, S. Gassó, D. A. Hegg, D. R. Collins, R. C. Flagan, J. H.
Seinfeld, V. Vitale, and C. Tomasi, Shipboard sunphotometer measurements
of aerosol optical depth spectra and columnar water vapor during ACE 2
and comparison to selected land, ship, aircraft, and satellite
measurements. *Tellus*, B 52, 594-619, 2000.

Welton, E. J., K. J. Voss, H. R. Gordon, H. Maring, A. Smirnov, B. N.
Holben, **B. Schmid**, J. M. Livingston, P. B. Russell, P. A. Durkee, P.
Formenti, M. O. Andreae, and O. Dubovik, Ground-based lidar measurements
of aerosols during ACE-2: lidar description, results, and comparisons
with other ground-based and airborne measurements. *Tellus*, B 52,
636-651, 2000.

Ingold, T., **B. Schmid**, C. Mätzler, P. Demoulin, and N. Kämpfer,
Modeled and Empirical Approaches for Retrieving Columnar Water Vapor
from Solar Transmittance Measurements in the 0.72, 0.82 and 0.94-μm
Absorption Bands. *J. Geophys. Res.*, 105(D19), 24327-24343, 2000.

**1999:**

**Schmid B.**, J. Michalsky, R. Halthore, M. Beauharnois, L. Harrison,
J. Livingston, P. Russell, B. Holben, T. Eck, and A. Smirnov, Comparison
of Aerosol Optical Depth from Four Solar Radiometers During the Fall
1997 ARM Intensive Observation Period, *Geophys. Res. Lett.*, Vol. 26,
No. 17, 2725-2728, 1999.

**1998:**

**Schmid, B.**, P.R. Spyak, S.F. Biggar, Ch. Wehrli, J. Sekler, T.
Ingold, C. Mätzler, and N. Kämpfer, "Evaluation of the applicability of
solar and lamp radiometric calibrations of a precision Sun photometer
operating between 300 and 1025 nm." *Applied Optics,* Vol. 37, No. 18,
3923-3941, 1998.

\[5 2-page peer-reviewed extended abstracts describing TARFOX and ACE-2
results in *J. Aerosol Sci.,* Vol. 29, Suppl. 1 and 2.\]

**1997:**

**Schmid, B.**, C. Mätzler, A. Heimo, and N. Kämpfer, Retrieval of
Optical Depth and Size Distribution of Tropospheric and Stratospheric
Aerosols by Means of Sun Photometry. *IEEE Transactions on Geoscience
and Remote Sensing,* Vol. 35, No. 1, 172-182, 1997.

**Two other relevant papers:**

**Schmid, B**., K. J. Thome, P. Demoulin, R. Peter, C. Mätzler, and J.
Sekler, Comparison of Modeled and Empirical Approaches for Retrieving
Columnar Water Vapor from Solar Transmittance Measurements in the 0.94
Micron Region. Journal of Geophysical Research, Vol. 101, No. D5,
9345-9358, 1996.

**Schmid, B**., and C. Wehrli, Comparison of Sun Photometer Calibration
by Langley Technique and Standard Lamp. Applied Optics, Vol. 34, No. 21,
4500-4512, 1995.

**(d) Jens Redemann**

**Abbreviated Curriculum Vitae**

Research Scientist, Bay Area Environmental Research Institute

MS-245, NASA Ames Research Center, Moffett Field, CA 94035-1000

Phone: (650) 604-6259 Fax: (650) 604-3625, email:
<jredemann@mail.arc.nasa.gov>

# PROFESSIONAL EXPERIENCE

  ---------------------------------- ------------------------------------
  Research Scientist                 April 1999 to present

  ---------------------------------- ------------------------------------

> Bay Area Environmental Research Institute, San Francisco.

  ---------------------------------- ------------------------------------
  Research Assistant                 May 1995 to March 1999

  ---------------------------------- ------------------------------------

> **University of California, Los Angeles, Department of Atmospheric
> Sciences.**

  ------------- ---------------------------------------------------------
  Lecturer      Jan. 1999 to March 1999

  ------------- ---------------------------------------------------------

**University of California, Los Angeles, Department of Atmospheric
Sciences.**

  ---------------------------------- ------------------------------------
  Tutor                              1997 to 1998

  ---------------------------------- ------------------------------------

**Ivy West Educational Services, Marina Del Rey, CA.**

  ---------------------------------- ------------------------------------
  Research Assistant                 June 1994 to April 1995

  ---------------------------------- ------------------------------------

Free University of Berlin, Germany. Department of Physics.

# EDUCATION

+----------------------------------+-----------------------------------+
| Ph.D. in Atmospheric Sciences.   | > 1999                            |
+----------------------------------+-----------------------------------+

> University of California, Los Angeles. Specialization: atmospheric
> physics and chemistry.

+----------------------------------+-----------------------------------+
| M.S. in Atmospheric Sciences.    | > 1997                            |
+----------------------------------+-----------------------------------+

> University of California, Los Angeles. Specialization: atmospheric
> physics and chemistry.

+----------------------------------+-----------------------------------+
| M.S. in Physics.                 | > 1995                            |
+----------------------------------+-----------------------------------+

> Free University of Berlin, Germany. Specialization in experimental
> physics and mathematics.

# RELEVANT RESEARCH EXPERIENCE

-   Developed inversion algorithms (C and IDL) and data analysis tools
    for aircraft-based lidar and sunphotometer measurements during field
    experiments (PEM, TARFOX).

-   Compared remotely sensed data to aerosol in situ measurements and
    devised techniques to retrieve the vertical structure of aerosol
    optical properties and radiative effects.

-   Involved in the development of a multi-wavelength, ground-based
    lidar system at the Free University of Berlin, Germany.

-   Provided solutions to scientific and numerical problems pertaining
    to aerosol physics and performed validation measurements relevant to
    Clean Room Technology for the computer chip industry.

-   Specialized course work in atmospheric sciences, geophysical fluid
    dynamics, cloud physics, radiative transfer and remote sensing.

# HONORS

+----------------------------------------------------------+-----------+
| > Invited Speaker at the Atmospheric Chemistry           | ####      |
| > Colloquium for Emerging Senior Scientists (ACCESS V).  | June 1999 |
+----------------------------------------------------------+-----------+
| > Outstanding Student Paper Award, American Geophysical  | > 1998    |
| > Union - fall meeting.                                  |           |
+----------------------------------------------------------+-----------+
| > NASA Global Change Research Fellowship Awards.         | >         |
|                                                          | 1996-1998 |
+----------------------------------------------------------+-----------+
| > UCLA Neiburger Award for excellence in the teaching of | > 1997    |
| > the atmospheric sciences.                              |           |
+----------------------------------------------------------+-----------+

# ORGANIZATIONS

American Association for Aerosol Research, American Geophysical Union,
Co-president of the UCLA - Atmospheric Sciences Graduate Student Group.

# RELEVANT PUBLICATIONS

**2000:**

Redemann, J., R.P. Turco, K.N. Liou, P.B. Russell, R.W. Bergstrom, B.
Schmid, J.M. Livingston, P.V. Hobbs, S. Ismail, E.V. Browell. Retrieving
the Vertical Structure of the Effective Aerosol Complex Index of
Refraction From Aerosol In Situ and Remote Sensing Methods During
TARFOX, *[J. Geophys. Res.]{.underline}*, 9949-9970, 2000.*.*

Redemann, J., R.P. Turco, K.N. Liou, P.B. Russell, R.W.Bergstrom, P.V.
Hobbs, E.V. Browell. Case Studies of the Vertical Structure of the
Aerosol Radiative Forcing During TARFOX, *[J. Geophys.
Res.]{.underline}*, 9971-9979, 2000*.*

**1999:**

Redemann, J., P.B. Russell, P. Hamill. Measurements and Modeling of
Aerosol Absorption and Single Scattering Albedo at Ambient Relative
Humidity, Presented at the AGU 1999 Fall Meeting, Dec. 13-17, San
Francisco, CA, 1999.

**1998:**

Redemann, J., R.P. Turco, R.F. Pueschel, M.A. Fenn, E.V. Browell and
W.B. Grant. A Multi-Instrument Approach for Characterizing the Vertical
Structure of Aerosol Properties: Case Studies in the Pacific Basin
Troposphere, *[J. Geophys. Res]{.underline}., 103,* 23,287 - 23,298,
1998.

Redemann, J., R.P. Turco, R.F. Pueschel, E.V. Browell, W.B. Grant.
Combining Data From Lidar and In Situ Instruments to Characterize the
Vertical Structure of Aerosol Optical Properties, Presented at the
Nineteenth International Laser Radar Conference, Annapolis, MD, July
6-10, 1998, *[NASA/CP-1998-207671/PT1]{.underline}*, pp.95-99, 1998.

**Before 1997:**

Redemann, J., R.P. Turco, R.F. Pueschel, E.V. Browell, W.B. Grant.
Comparison of Aerosol Measurements by Lidar and In Situ Methods in the
Pacific Basin Troposphere, in '*[Advances in Atmospheric Remote Sensing
with Lida]{.underline}r*', A. Ansmann, R.Neuber, P.Rairoux, U.Wandinger
(eds.), pp.55-58, Springer, Berlin, 1996.

Pueschel, R.F.; D.A. Allen, C. Black, S. Faisant, G.V. Ferry, S.D.
Howard, J.M. Livingston, J. Redemann, C.E. Sorensen, S. Verma, Condensed
Water in Tropical Cyclone "Oliver", 8 February 1993, *[Atmospheric
Research]{.underline}*, 38, pp.297-313, 1995.

**(e) John Livingston**

**Abbreviated Curriculum Vitae**

Senior Research Meteorologist, Applied Physical Sciences Laboratory,

SRI International, Menlo Park, CA 94025

Specialized Professional Competence

> Atmospheric physics and meteorology; atmospheric radiometry; computer
> simulation of atmospheric remote sensing systems; numerical analysis
> and inversion of in-situ and remotely sensed atmospheric data

Representative Research Assignments at SRI (Since 1978)

> Acquisition and analysis of ground-based, airborne, and shipboard
> sunphotometer measurements
>
> Validation of satellite particulate extinction measurements (SAM II,
> SAGE I, and SAGE II), and corresponding studies of the global
> distribution of stratospheric aerosols
>
> Analysis of *in situ* measurements of stratospheric and tropospheric
> aerosols
>
> Acquisition, modeling and analysis of Differential Absorption Lidar
> measurements of tropospheric ozone
>
> Simulation of passive sensor radiance measurements to infer range to
> an absorbing gas
>
> Experimental study of aerosol effects on solar radiation using remote
> sensors
>
> Error analysis and simulation of lidar aerosol measurements
>
> Analysis of lidar propagation through fog, military smoke, and dust
> clouds
>
> Evaluation of the lidar opacity method for enforcement of stationary
> source emission standards
>
> Weather forecasting for large-scale air pollution field study
>
> Testing and evaluation of an offshore coastal dispersion computer
> model
>
> Application of objective wind field and trajectory models to
> meteorological measurements

Professional Experience

> Research Meteorologist to Senior Research Meteorologist, SRI
> International (1978-present)
>
> Research assistant, University of Arizona Institute of Atmospheric
> Physics (1974-1977)
>
> NASA Kennedy Space Center (1975-1976): participant in thunderstorm
> electrification studies

Academic Background

> University of Notre Dame Year-in-Japan Program (1971-1972), Sophia
> University, Tokyo, Japan
>
> B.S. summa cum laude in earth sciences (1974), University of Notre
> Dame, Notre Dame, IN
>
> M.S. in atmospheric sciences (1977), University of Arizona, Tucson, AZ
>
> M.B.A. with highest honors (1992), Santa Clara University, Santa
> Clara, CA

Honors

> NASA Ames Research Center Contractor of the Year (1997), NASA
> Certificate of Recognition (1992) for co-authored technical paper,
> NASA Group Achievement Award (1989) for Airborne Antarctic Ozone
> Experiment

Professional Associations

> American Geophysical Union

**PUBLICATIONS**

**2000:**

Collins, D. R., H. H. Jonsson, J. H. Seinfeld, R.C. Flagan, S. Gassó, D.
A. Hegg, B. Schmid, P. B. Russell, J. M. Livingston, E. Öström, K. J.
Noone, L. M. Russell, and J. P. Putaud, In situ aerosol size
distributions and clear column radiative closure during ACE-2. *Tellus*,
B 52, 498-525, 2000.

Durkee, P. A., K. E. Nielsen, P. J. Smith, P. B. Russell, B. Schmid**,**
J. M. Livingston, B. N. Holben, D. R. Collins, R. C. Flagan, J. H.
Seinfeld, K. J. Noone, E. Öström, S. Gassó, D. A. Hegg, L. M. Russell,
T. S. Bates, and P. K. Quinn. Regional aerosol properties from satellite
observations: ACE-1, TARFOX and ACE-2 results. *Tellus,* B 52, 484-497,
2000.

Ferrare, R., S. Ismail, E. Browell, V. Brackett, M. Clayton, S. Kooi, S.
H. Melfi, D. Whiteman, G. Schwemmer, K. Evans, P. Russell, J.
Livingston, B. Schmid, B. Holben, L. Remer, A. Smirnov, P. Hobbs.
Comparisons of aerosol optical properties and water vapor among ground
and airborne lidars and sun photometers during TARFOX. *J. Geophys.
Res*., *105*(D8), 9917-9933, 2000.

Ferrare, R., S. Ismail, E. Browell, V. Brackett, S. Kooi, M. Clayton, P.
V. Hobbs, S. Hartley, J. P. Veefkind, P. Russell, J. Livingston, D.
Tanre, and P. Hignett. Comparisons of LASE, aircraft, and satellite
measurements of aerosol optical properties and water vapor during
TARFOX, *J. Geophys. Res*., *105*(D8), 9935-9947, 2000.

Flamant, C., J. Pelon, P. Chazette, V. Trouillet, P. K. Quinn, R.
Frouin, D. Bruneau, J. F. Leon, T. S. Bates, J. Johnson, and J.
Livingston. Airborne lidar measurements of aerosol spatial distribution
and optical properties over the Atlantic Ocean during a European
pollution outbreak of ACE-2. *Tellus,* B 52, 662-677, 2000.

Gassó, S., D. A. Hegg, K. J. Noone, D. S. Covert, B. Schmid, P. B.
Russell, J. M. Livingston, P. A. Durkee, and H. H. Jonsson, Influence of
humidity on the aerosol scattering coefficient and its effect on the
upwelling radiance during ACE2. *Tellus,* B 52, 546-567, 2000.

Hartley, W. S., P. V. Hobbs, J. L. Ross, P. B. Russell and J. M.
Livingston, Properties of aerosols aloft relevant to direct radiative
forcing off the mid-Atlantic coast of the United States, *J. Geophys.
Res*., *105*(D8), 9859-9885, 2000.

> Livingston, J. M., V. N. Kapustin, B. Schmid, P. B. Russell, P. K.
> Quinn, T. S. Bates, P. A. Durkee, P. J. Smith, V. Freudenthaler, M.
> Wiegner, D. S. Covert, S. Gassó, D. Hegg, D. R. Collins, R. C. Flagan,
> J. H. Seinfeld, V. Vitale and C. Tomasi, Shipboard sunphotometer
> measurements of aerosol optical depth spectra and columnar water vapor
> during ACE-2 and comparison with selected land, ship, aircraft, and
> satellite measurements. *Tellus*, B 52, 594-619, 2000.

Redemann, J., R. P. Turco, K. N. Liou, P. B. Russell, R. W. Bergstrom,
B. Schmid, J. M. Livingston, P. V. Hobbs, W. S. Hartley, S. Ismail, R. A
Ferrare, E. V. Browell, Retrieving the Vertical Structure of the
Effective Aerosol Complex Index of Refraction From a Combination of
Aerosol In Situ and Remote Sensing Measurements During TARFOX. *J.
Geophys. Res.*, *105*(D8), 9949-9970, 2000*.*

Schmid, B., J. M. Livingston, P. B. Russell, P. A. Durkee, H. H.
Jonsson, D. R. Collins, R. C. Flagan, J. H. Seinfeld, S. Gassó, D. A.
Hegg, E. Öström, K. J. Noone, E. J. Welton, K. J. Voss, H. R. Gordon, P.
Formenti, and M. O. Andreae, Clear sky closure Clear sky closure studies
of lower tropospheric aerosol and water vapor during ACE-2 using
airborne sunphotometer, airborne in-situ, space-borne, and ground-based
measurements. *Tellus B*, B 52, 568-593, 2000.

Welton, E. J., K. J. Voss, H. R. Gordon, H. Maring, A. Smirnov, B. N.
Holben, B. Schmid**,** J. M. Livingston, P. B. Russell, P. A. Durkee, P.
Formenti, M. O. Andreae, and O. Dubovik, Ground-based lidar measurements
of aerosols during ACE-2: lidar description, results, and comparisons
with other ground-based and airborne measurements. *Tellus*, B 52,
636-651, 2000.

**1999:**

Russell, P. B., J. M. Livingston, P. Hignett, S. Kinne, J. Wong, and P.
V. Hobbs, Aerosol-induced radiative flux changes off the United States
Mid-Atlantic coast: Comparison of values calculated from sunphotometer
and in situ data with those measured by airborne pyranometer, *J.
Geophys. Res.,* 104, 2289-2307, 1999.

Tanre, D., L. A. Remer, Y. J. Kaufman, S. Mattoo, P. V. Hobbs, J. M.
Livingston, P. B. Russell, and A. Smirnov, Retrieval of aerosol optical
thickness and size distribution over ocean from the MODIS airborne
simulator during TARFOX, *J. Geophys. Res*., *104*, 2261-2278, 1999.

Veefkind, J. P., G. de Leeuw, P. A. Durkee, P. B. Russell, P. V. Hobbs,
and J. M. Livingston, Aerosol optical depth retrieval using ATSR-2 and
AVHRR data during TARFOX, *J. Geophys. Res*., *104*, 2253-2260, 1999.

Schmid, B., J. Michalsky, R. Halthore, M. Beauharnois, L. Harrison, J.
Livingston, P.. Russell, B. Holben, T. Eck, and A. Smirnov, Comparison
of aerosol optical depth from four solar radiometers during the Fall
1997 ARM Intensive Observation Period, *Geophys. Res*. *Lett*., *104*,
2261-2278, 1999.

**1998:**

\[6 2-page peer-reviewed extended abstracts in *J. Aerosol. Sci.*
describing TARFOX and ACE-2 results.\]

**1997:**

Hegg, D. A., J. Livingston, P. V. Hobbs, T. Novakov, and P. B. Russell,
Chemical Apportionment of Aerosol Column Optical Depth Off the
Mid-Atlantic Coast of the United States. *J. Geophys. Res. , 102* ,
25,293-25,303, 1997.

**Five Other Relevant Papers:**

Livingston, J.M., and P. B. Russell, Retrieval of aerosol size
distribution moments from multiwavelength particulate extinction
measurements. *J. Geophys. Res.*, *94*, 8425-8433, 1989.

Pueschel, R.F., J. M. Livingston, G. V. Ferry, and T. E. DeFelice,
Aerosol abundances and optical characteristics in the Pacific basin free
troposphere. *Atmos. Envir.*, *28*, 951-960, 1993.

Pueschel, R.F., J. M. Livingston, P. B. Russell, and S. Verma, Physical
and optical prop­erties of the Pinatubo volcanic aerosol: aircraft
observations with impactors and a Sun-tracking photometer. *J. Geophys.
Res.*, *99*, 12,915-12,922, 1994.

Russell, P. B., J. M. Livingston, R. F. Pueschel, J. J. Bauman, J. B.
Pollack, S. L. Brooks, P. Hamill, L. W. Thomason, L. L. Stowe, T.
Deshler, E. G. Dutton, and R. W. Bergstrom, Global to Microscale
Evolution of the Pinatubo Volcanic Aerosol, Derived from Diverse
Measurements and Analyses. *J. Geophys. Res.*, *101*, 18,745-18,763,
1996.

Russell, P.B., J.M. Livingston, and E.E. Uthe, Aerosol-Induced Albedo
Change: Measurement and Modeling of an Incident. *J. Atmos. Sci.*, *36,*
1587-1608, 1979.