**Airborne Sunphotometry and Integrated Analyses of Dust, Other
Aerosols, and Water Vapor in the**

**Puerto Rico Dust Experiment (PRIDE)**

**Philip B. Russell,**

**NASA Ames Research Center, Moffett Field, CA**

**Co-Investigators:**

## **Beat Schmid^1^, Jens Redemann^1^, John M. Livingston^2^, Peter Pilewskie^3^**

**^1^Bay Area Environmental Research Institute, San Francisco, CA**

**^2^SRI International, Menlo Park, CA**

**^3^NASA Ames Research Center, Moffett Field, CA**

A proposed investigation presented at

PRIDE Videocon

NASA Goddard and Ames

24 January 2000

**What we want to do**

**&**

**How we plan to do it**

**Task 1. Install AATS-6 on the SPAWAR Navajo**

+--------------------------------------------------+-------------------+
| !                                                | ##### Dome        |
| [](media/image1.pct){width="4.365277777777778in" |                   |
| height="5.316666666666666in"}                    | **Radius = 4"**   |
+--------------------------------------------------+-------------------+
| ![                                               |                   |
| ](media/image2.jpeg){width="6.567361111111111in" |                   |
| height="4.381944444444445in"}                    |                   |
+--------------------------------------------------+-------------------+

**AATS = Ames Airborne Tracking Sunphotometer**

**How AATS-14 flew in TARFOX and ACE-2**

###  Sunphotometer

####  Dome radius = 4"

![](media/image3.jpeg){width="6.741666666666666in"
height="3.814583333333333in"}

###### Next Tasks: Address Yoram's Lists 

**Yoram's Lists\***

**What to measure in PRIDE:**

• Spectral optical thickness under Terra over glint free and glint
regions

**• Ground based measurements of dust absorption, scattering and iron
concentration during a given period of time**

**• Vertical profiles of whatever we can measure**

**• Ocean spectral properties**

**Why:**

• Dust is most abundant aerosol, yet its properties least known. What
can we measure?

• Dust fertilizes the ocean. What is the relationship between the dust
optical thickness, absorption and iron concentration ? How variable is
it?

• Need to know how badly dust (aspherical, inhomogeneous) degrades MODIS
and other retrievals (which assume spherical homogeneous particles).

• In coastal regions, need to know how badly underwater reflection
degrades MODIS retrievals.

• The best dust measurements are from ground based instrumentation. [How
representative are they of the vertical column?]{.underline}

\*Yoram Kaufman's email of 1/17/00

Example:

AATS-6 continuous transect of multi- AOD

demonstrates quantitatively how ATSR-2 retrieval accuracy exceeds AVHRR

![](media/image4.pct){width="5.313888888888889in"
height="7.914583333333334in"}

Veefkind et al., *JGR*, 1999

Example:

AATS-6 underflights of MODIS Airborne Simulator (MAS) quantify how MAS
retrieval accuracy depends on AOT magnitude

![](media/image5.pct){width="5.513888888888889in"
height="3.8069444444444445in"}![](media/image6.pct){width="5.513888888888889in"
height="4.041666666666667in"}

Tanre et al., *JGR*, 1999

**Yoram's Lists\***

**What to measure in PRIDE:**

• Spectral optical thickness under Terra over glint free and glint
regions

**• Ground based measurements of dust absorption, scattering and iron
concentration during a given period of time**

**• Vertical profiles of whatever we can measure**

**• Ocean spectral properties**

**Why:**

• Dust is most abundant aerosol, yet its properties least known. What
can we measure?

• Dust fertilizes the ocean. What is the relationship between the dust
optical thickness, absorption and iron concentration ? How variable is
it?

• Need to know how badly dust (aspherical, inhomogeneous) degrades MODIS
and other retrievals (which assume spherical homogeneous particles).

• In coastal regions, need to know how badly underwater reflection
degrades MODIS retrievals.

• The best dust measurements are from ground based instrumentation. [How
representative are they of the vertical column?]{.underline}

\*Kaufman email, 1/17/00

Example:

AATS-6 and -14 AOD spectra and

[continuous vertical profiles]{.underline} quantify how dust changes
bias of AVHRR retrievals

![](media/image7.pct){width="5.517361111111111in"
height="7.353472222222222in"}

Livingston et al., *Tellus*, 2000; Schmid et al., *Tellus*, 2000

We need many comparisons to see if the

dust/no-dust difference is statistically stable

![](media/image8.pct){width="6.3590277777777775in" height="7.225in"}

Durkee et al., *Tellus*, 2000

Livingston et al., *Tellus*, 2000; Schmid et al., *Tellus*, 2000

The cardinal rule of satellite validation

Whenever possible, use validation instruments and methods that have a
proven track record:

+-------------------------------------------+----+--------------------+
| > \- Error bars based on a comprehensive  | }  | Documented in the  |
| > error analysis                          |    | peer-reviewed      |
|                                           |    | literature         |
+-------------------------------------------+----+--------------------+
| > \- History of successful                |    |                    |
| > intercomparisons to other accepted      |    |                    |
| > techniques                              |    |                    |
+-------------------------------------------+----+--------------------+

The cardinal rule of satellite validation

Whenever possible, use validation instruments and methods that have a
proven track record:

+-------------------------------------------+----+--------------------+
| > \- Error bars based on a comprehensive  | }  | Documented in the  |
| > error analysis                          |    | peer-reviewed      |
|                                           |    | literature         |
+-------------------------------------------+----+--------------------+
| > \- History of successful                |    |                    |
| > intercomparisons to other accepted      |    |                    |
| > techniques                              |    |                    |
+-------------------------------------------+----+--------------------+

Rule 2:

Demand spatiotemporal coincidence between satellite data and validation
data.

(We live in a very inhomogeneous, changing world.)

+-----------------------------------------------------------------------+
| > \- Mobility & spatiotemporal continuity of validation measurements  |
| > really help to achieve this coincidence                             |
+-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------+

We've demonstrated lots of other measurements and collaborative analyses
that would be useful in PRIDE

• Ways to get [absorption]{.underline} (see Yoram's list) of the
[ambient, unperturbed]{.underline} aerosol:

-   AATS vertical profiles in the MicroPulse Lidar (MPL) beam, to get
    B/E(z); hence (z) (Redemann et al., 2000; Schmid et al., 2000;
    Welton et al., 2000)

-   Combine SSFR Flux(z,) with AATS AOD(z,) to get diffuse/direct
    Flux(z,); hence () (Russell et al., 1999b)

• Many [comparisons]{.underline} to airborne [in situ]{.underline}
measurements, to test [closure]{.underline}:

-   AOD() from AATS, nephelometer, PSAP, size spectrometers,
    chemistry(r) (Schmid et al., 2000; Collins et al., 2000; Livingston
    et al., 2000)

-   n(r) from AATS vs size spectrometers (corrected for inlet losses,
    evaporation, calibration, etc.) (Schmid et al., 2000)

• Water vapor column from AATS (Livingston et al., 2000):

-   Compare to satellite retrievals; test correlation with AOD retrieval
    errors

-   Study effect on aerosol size, composition

![](media/image9.pct){width="6.5in" height="4.555555555555555in"}

Aerosol single-scattering albedo profiles determined for TARFOX flight
1728 (July 17, 1996) by two techniques. [Solid line]{.underline}:
derived by Redemann et al. (2000b) using *in situ* particle size
distributions and aerosol layer complex refractive index estimates from
Redemann et al. (2000a) that produce best agreement among profiles of
lidar backscatter, sunphotometer extinction, and relative size
distribution. Values were used in the first band of the Fu-Liou
radiative transfer model (0.2 µm \< \< 0.7 µm). [Dashed
line]{.underline}: derived by Hartley et al. (2000) at 450 nm by
combining in situ scattering, absorption, and size distribution
measurements. The gray-shaded area represents their uncertainty
estimates based on one standard deviation plus instrumental error.

![](media/image10.pct){width="7.135416666666667in" height="6.0in"}

Comparison between aerosol-induced change in downwelling solar flux
derived from C-130 pyranometer measurements (data points) and calculated
(curves) for size distributions retrieved from sunphotometer optical
depth spectra using an aqueous sulfate real refractive index and a range
of imaginary indexes to give the (550) values shown. The error bar
(cross) shows the uncertainty in flux change and broadband visible
optical depth determined from the C-130 pyranometer measurements
(Russell, et al., 1999b).

![](media/image11.pct){width="5.997916666666667in"
height="4.4in"}Comparison of aerosol optical depth spectra for the
marine boundary layer (31-1111 m) during Pelican flight tf20 in ACE 2 on
July 8, 1997 (Schmid et al., 2000).

![](media/image11.pct){width="5.997916666666667in" height="4.50625in"}

Comparison of marine boundary layer aerosol size distributions from in
situ measurements and inverted from AATS-14 extinction spectra measured
on Pelican flight tf15 in ACE 2 on July 17, 1997. Dashed lines indicate
uncertainty of the in situ results (Schmid et al., 2000).

![](media/image12.pct){width="5.999305555555556in"
height="4.963888888888889in"}

Left panel: Profile of the columnar water vapor above the Pelican
aircraft measured in ACE-2 south of the coast of Tenerife. Right panel:
Water vapor density derived by differentiating the profile in the left
panel. Also shown for comparison is the profile obtained by combining
readings of a humidograph and outside temperature on Pelican
(humidograph data courtesy of S. Gasso, University of Washington).
(Schmid et al., 2000)

![](media/image11.pct){width="7.495833333333334in"
height="5.634722222222222in"}

Scatter diagram of columnar water vapor calculated from radiosonde
measurements and from AATS-6 measurements during ACE-2. Each AATS-6 data
point represents the mean calculated over the time period spanned by the
radiosonde measurements; horizontal bars show the corresponding standard
deviation (wide ticks) and the range (narrow ticks) for that time period
(Livingston et al., 2000).

Vertical profiles of aerosol extinction are obtained by vertically
differentiating AATS [continuous vertical profiles]{.underline} of AOD

![](media/image13.pct){width="5.997222222222222in"
height="7.738888888888889in"}

Left panel: Profiles of aerosol optical depth at four selected AATS-14
wavelengths (380, 500, 864 and 1558 nm) measured in ACE-2 south of the
coast of Tenerife. Right panel: Aerosol extinction profiles derived by
differentiating the profiles in the left panel. (Schmid et al., 2000b)

TARFOX and ACE-2 Papers That Use Data from the Ames Airborne Tracking
Sunphotometers (AATS-6 and AATS-14)

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.

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

Durkee, P. A., K. E. Nielsen, P. B. Russell, P. B., B. Schmid, J. M.
Livingston, D. Collins, , R. Flagan, J. Seinfeld, K. Noone, S. Gasso, D.
Hegg, T. S. Bates, and P. K. Quinn, "Regional aerosol properties from
satellite observations: ACE-1, TARFOX and ACE-2 results." *J. Aerosol
Sci. 29*(Suppl 1): S1149, 1998.

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* in press, 2000.

Ferrare, R., S. Ismail, E. Browell, V. Brackett, S. Kooi, M. Clayton, 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*., in press, 2000.

Ferrare, R., S. Ismail, E. Browell, V. Brackett, S. Kooi, M. Clayton, P.
Hobbs, S. Hartley, J.P. Veefkind, P. Russell, J. Livingston, D. Tanre,
P. Hignett, Comparisons of LASE, aircraft, and satellite measurements of
aerosol optical properties and water vapor during TARFOX, *J. Geophys.
Res*., in press, 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.* (2^nd^ Special Issue on TARFOX), in press, 2000.

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.

Hobbs, P. V., T. Novakov, P. Russell, J. M. Livingston, and J. L. Ross,
"Relative contributions of atmospheric aerosol constituents to optical
depths and direct radiative forcing on the United States east coast."
*J. Aerosol Sci. 29*(Suppl 1): S1297-S1298, 1998.

Ismail, S., E.V. Browell, R. Ferrare, S. A. Kooi, M. Clayton, V.
Brackett, P. Russell, LASE Measurement of Aerosol and Water Vapor
Profiles Measured During TARFOX, *J. Geophys. Res.,* submitted 1999.

Livingston, J. M., V. Kapustin, B. Schmid, P. B. Russell, P. A. Durkee,
T. S. Bates, and P. K. Quinn, "Shipboard sunphotometer measurements of
aerosol optical depth spectra and columnar water vapor during ACE-2*, J.
Aerosol Sci. 29*(Suppl 1): S257-S258, 1998.

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 in press, 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, 137-140, 2000.

Powell, Donna M., John A. Reagan, Manuel A. Rubio, Wayne H. Erxleben,
James D. Spinhirne, ACE-2 Multiple Angle Micro-Pulse Lidar Observations
from Las Galletas, Tenerife, Canary Islands, Tellus, in press, 2000.

Redemann, J., R. Turco, Liou, Russell, Bergstrom, Schmid, Livingston,
Hobbs, Hartley, Ismail, Ferrare, Browell, Retrieving the Vertical
Structure of the Aerosol Complex Index of Refraction From Aerosol In
Situ and Remote Sensing Measurements During TARFOX, *J. Geophys. Res*.,
in press, 2000.

Redemann, J., R. Turco, Liou, Russell, Bergstrom, Hobbs, Browell, Case
Studies of the Vertical Structure of the Direct Aerosol Radiative
Forcing During TARFOX, *J. Geophys. Res*., in press, 2000.

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

Russell, P. B., P. Hignett, J. M. Livingston, B. Schmid, A. Chien, P. A.
Durkee, P. V. Hobbs, T. S. Bates, and P. K. Quinn, Radiative flux
changes by aerosols from North America, Europe, and Africa over the
Atlantic Ocean: Measurements and calculations from TARFOX and ACE 2.
Fifth International Aerosol Conference, Edinburgh, Scotland, 14-18
September 1998, *J. Aerosol Sci. 29*(Suppl 1): S255-S256, 1998.

Russell, P. B., J. M. Livingston, B. Schmid, A. Chien, S. Gasso, D.
Hegg, K. Noone, D. Collins, H. Jonsson, K. Nielsen, P. Durkee, R.
Flagan, J. Seinfeld, T. S. Bates, and P. K. Quinn, "Clear column closure
studies of urban-marine and mineral-dust aerosols using aircraft, ship,
and satellite measurements in ACE-2." *J. Aerosol Sci. 29*(Suppl 1):
S1143-S1144, 1998.

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, 1999.

Russell, P. B., J. M. Livingston, P. Hignett, S. Kinne, J. Wong, A.
Chien, R. Bergstrom, P. Durkee, 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.

Schmid, B., J. M. Livingston, P. B. Russell, P. A. Durkee, H. Jonsson,
K. E. Nielsen, S. Gasso, E. J. Welton, K. Voss, P. Formenti, and M. O.
Andreae, "Three dimensional investigation of lower tropospheric aerosol
and water vapor during ACE-2 by means of airborne sunphotometry." *J.
Aerosol Sci. 29*(Suppl 1): S1145-

Schmid, B., J. J. Michalsky, R. N. Halthore, M. C. Beauharnois, L. C.
Harrison, J. M. Livingston, and P. B. Russell, Comparison of aerosol
optical depth from four solar radiometers during the Fall 1997 ARM
Intensive Observation Period, *Geophys. Res. Lett., 27*, 2725-2728,
1999.

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*
in press, 2000.

Tanré, 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.

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

+-----------------+-----------------------------------------------------+
| **Investigation |                                                     |
| Title: Airborne |                                                     |
| Sunphotometry   |                                                     |
| and Integrated  |                                                     |
| Analyses of     |                                                     |
| Dust, Other     |                                                     |
| Aerosols, and   |                                                     |
| Water Vapor in  |                                                     |
| the Puerto Rico |                                                     |
| Dust Experiment |                                                     |
| (PRIDE)**       |                                                     |
+-----------------+-----------------------------------------------------+
| Principal       | Philip B. Russell                                   |
| Investigator    |                                                     |
| and team        | Atmospheric Chemistry and Dynamics Branch           |
|                 |                                                     |
| PI: Philip B.   | NASA Ames Research Center                           |
| Russell         |                                                     |
|                 | MS 245-5                                            |
| Co-Is:          |                                                     |
|                 | Moffett Field, CA 94035-1000                        |
| Beat Schmid     |                                                     |
|                 | prussell@mail.arc.nasa.gov                          |
| Jens Redemann   |                                                     |
|                 | Phone: 650-604-5404. Fax: 650-604-6779              |
| John M.         |                                                     |
| Livingston      | Beat Schmid, Bay Area Environmental Research        |
|                 | Institute, 650-604-5933                             |
| Peter Pilewskie |                                                     |
|                 | Jens Redemann, Bay Area Environmental Research      |
|                 | Institute, 650-604-6259                             |
|                 |                                                     |
|                 | John M. Livingston, SRI International, 650-859-4174 |
|                 |                                                     |
|                 | Peter Pilewskie, NASA Ames Research Center,         |
|                 | 650-604-0746                                        |
+-----------------+-----------------------------------------------------+
| Investigation   |                                                     |
| objectives:     |                                                     |
|                 |                                                     |
| (1) Improve     |                                                     |
|                 |                                                     |
|   understanding |                                                     |
|     of dust,    |                                                     |
|     other       |                                                     |
|     aerosol,    |                                                     |
|     and water   |                                                     |
|     vapor       |                                                     |
|     effects on  |                                                     |
|     radiative   |                                                     |
|     transfer,   |                                                     |
|     radiation   |                                                     |
|     budgets and |                                                     |
|     climate in  |                                                     |
|     the         |                                                     |
|     Caribbean   |                                                     |
|     region      |                                                     |
|                 |                                                     |
| (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.    |                                                     |
|                 |                                                     |
| Tasks:          |                                                     |
|                 |                                                     |
| \(a\) Integrate |                                                     |
| an Ames         |                                                     |
| Airborne        |                                                     |
| Tracking        |                                                     |
| Sunphotometer   |                                                     |
| on a PRIDE      |                                                     |
| aircraft (e.g., |                                                     |
| AATS-6 on the   |                                                     |
| SPAWAR Navajo,  |                                                     |
| or AATS-14 on   |                                                     |
| the CIRPAS Twin |                                                     |
| Otter). (b)     |                                                     |
| Calibrate AATS  |                                                     |
| before and      |                                                     |
| after PRIDE.    |                                                     |
| (c) Provide     |                                                     |
| continuous      |                                                     |
| realtime        |                                                     |
| measurements of |                                                     |
| aerosol and     |                                                     |
| thin cloud      |                                                     |
| optical depth   |                                                     |
| spectra and     |                                                     |
| water vapor     |                                                     |
| column contents |                                                     |
| during PRIDE    |                                                     |
| flights. (d)    |                                                     |
| Use these data  |                                                     |
| in flight       |                                                     |
| direction and   |                                                     |
| planning. (e)   |                                                     |
| Compare results |                                                     |
| to those of the |                                                     |
| satellite       |                                                     |
| sensors listed  |                                                     |
| above; in cases |                                                     |
| of              |                                                     |
| disagreement,   |                                                     |
| investigate     |                                                     |
| causes and      |                                                     |
| retrieval       |                                                     |
| algorithm       |                                                     |
| improvements.   |                                                     |
| (f) For         |                                                     |
| aircraft        |                                                     |
| profiles derive |                                                     |
| profiles of     |                                                     |
| aerosol         |                                                     |
| extinction      |                                                     |
| spectra and     |                                                     |
| water vapor     |                                                     |
| density. (g)    |                                                     |
| Combine these   |                                                     |
| data with those |                                                     |
| from the        |                                                     |
| Pilewskie SSFR  |                                                     |
| and conduct new |                                                     |
| analyses of     |                                                     |
| aerosol         |                                                     |
| radiative       |                                                     |
| forcing         |                                                     |
| sensitivity,    |                                                     |
| single          |                                                     |
| scattering      |                                                     |
| albedo, and the |                                                     |
| solar spectral  |                                                     |
| radiative       |                                                     |
| energy budget.  |                                                     |
| (h) Derive      |                                                     |
| aerosol size    |                                                     |
| distributions   |                                                     |
| from optical    |                                                     |
| depth and       |                                                     |
| extinction      |                                                     |
| spectra. (i)    |                                                     |
| Combine data    |                                                     |
| with in situ    |                                                     |
| measurements of |                                                     |
| chemical        |                                                     |
| composition,    |                                                     |
| size            |                                                     |
| distribution,   |                                                     |
| hygroscopic     |                                                     |
| growth, and     |                                                     |
| si              |                                                     |
| ngle-scattering |                                                     |
| albedo to       |                                                     |
| provide tests   |                                                     |
| of closure and  |                                                     |
| integrated      |                                                     |
| assessments of  |                                                     |
| aerosol and     |                                                     |
| trace gas       |                                                     |
| radiative       |                                                     |
| effects.        |                                                     |
+-----------------+-----------------------------------------------------+
| Outputs (what   |                                                     |
| and when):      |                                                     |
|                 |                                                     |
| -   Aerosol and |                                                     |
|     thin cloud  |                                                     |
|     optical     |                                                     |
|     depth       |                                                     |
|     spectra     |                                                     |
|     (380 to     |                                                     |
|     1020 or     |                                                     |
|     1558 nm)    |                                                     |
|     and water   |                                                     |
|     vapor       |                                                     |
|     column      |                                                     |
|     contents,   |                                                     |
|     in real     |                                                     |
|     time color  |                                                     |
|     displays.   |                                                     |
|     Produced    |                                                     |
|                 |                                                     |
|    continuously |                                                     |
|     throughout  |                                                     |
|     A/C flight  |                                                     |
|     when        |                                                     |
|                 |                                                     |
| sunphotometer's |                                                     |
|     view of sun |                                                     |
|     is not      |                                                     |
|     blocked by  |                                                     |
|     thick       |                                                     |
|     clouds      |                                                     |
|     (\>\~3) or  |                                                     |
|     A/C         |                                                     |
|                 |                                                     |
|    obstructions |                                                     |
|     (e.g.,      |                                                     |
|     tail,       |                                                     |
|     antennas).  |                                                     |
|                 |                                                     |
| -   For A/C     |                                                     |
|     profiles,   |                                                     |
|     haze        |                                                     |
|     extinction  |                                                     |
|     spectra     |                                                     |
|     profiles    |                                                     |
|     (380 to     |                                                     |
|     1020 or     |                                                     |
|     1558 nm)    |                                                     |
|     and water   |                                                     |
|     vapor       |                                                     |
|                 |                                                     |
|   concentration |                                                     |
|     profiles.   |                                                     |
|     Produced    |                                                     |
|     after       |                                                     |
|     flight from |                                                     |
|     smoothed    |                                                     |
|     profiles of |                                                     |
|     data        |                                                     |
|     resulting   |                                                     |
|     from #1.    |                                                     |
|     Requires    |                                                     |
|     reasonable  |                                                     |
|     hori        |                                                     |
| zontal/temporal |                                                     |
|                 |                                                     |
|    homogeneity. |                                                     |
|                 |                                                     |
| Integrated      |                                                     |
| analyses (see   |                                                     |
| above) and      |                                                     |
| publications    |                                                     |
| produced        |                                                     |
| several months  |                                                     |
| to years after  |                                                     |
| measurements,   |                                                     |
| depending in    |                                                     |
| part on         |                                                     |
| availability of |                                                     |
| others' data    |                                                     |
| and analyses,   |                                                     |
| plus funding    |                                                     |
| levels.         |                                                     |
+-----------------+-----------------------------------------------------+
| Activity        |                                                     |
| timetable:      |                                                     |
|                 |                                                     |
| 2000:           |                                                     |
|                 |                                                     |
| Jan-Feb:        |                                                     |
| Funding         |                                                     |
| Decision        |                                                     |
|                 |                                                     |
| Feb-Apr: A/C    |                                                     |
| Integration     |                                                     |
| Planning, Fit   |                                                     |
| Checks          |                                                     |
|                 |                                                     |
| May:            |                                                     |
| Pre-Campaign    |                                                     |
| Sunphotometer   |                                                     |
| Aerosol/Water   |                                                     |
| Vapor           |                                                     |
| Calibration,    |                                                     |
| Mauna Loa       |                                                     |
| Observatory     |                                                     |
|                 |                                                     |
| 1-21 Jun: A/C   |                                                     |
| Integration and |                                                     |
| Test Flights    |                                                     |
|                 |                                                     |
| 26 Jun-21 Jul:  |                                                     |
| PRIDE           |                                                     |
| Deployment,     |                                                     |
| Roosevelt       |                                                     |
| Roads, PR       |                                                     |
|                 |                                                     |
| Aug-Oct:        |                                                     |
| Post-Campaign   |                                                     |
| Sunphotometer   |                                                     |
| Aerosol/ Water  |                                                     |
| Vapor           |                                                     |
| Calibration,    |                                                     |
| Mauna Loa       |                                                     |
| Observatory     |                                                     |
+-----------------+-----------------------------------------------------+