SAFARI 2000 Airborne Sunphotometer Aerosol Optical Depth and Water Vapor Data

This README file describes the format of the 14-channel Ames Airborne Tracking 
Sunphotometer (AATS-14) results obtained during SAFARI-2000 aboard the UW CV-580 
airplane.

The files have the names UWxxxx_A14_ddmmmyy_all_r.asc (entire flight), and for selected
cases there are aerosol extinction profiles (UWxxxx_A14_ddmmmyy_hhmm_p.asc)
The exact format is described in the header of each file. xxxx is the CV-580 flight number.
For the profile files hhmm is the start time of the profile.

See file revision.txt for revision information.

The data are Q/A-ed and obstructions by clouds or aircraft structures have been removed
Or flagged. There are data that have AOD_flag=0 this means the AOD in one or more
channels are BAD but the water vapor is OK. Thus for AOD: only use data if AOD_flag=1. 

Please check second header line carefully to identify results influenced by dirt on the
optical window.


The files are intended to be self explanatory, but please do not hesitate to e-mail us for questions.

We have computed fit coefficients for AOD and (extinction if applicable) that will allow you
to interpolate the values to any desired wavelength in the range from 350 to 1560nm. 

The fit is 

ln (tau_aero)=a0 + a1 * ln (lambda) +a2 * (ln (lambda))^2 

where lambda has to be in units of micrometers. In the coefficient columns in the files the
first column is a2, the second is a1 and the third is a0. We highly recommend using this
interpolation in cases where the wavelengths don't match. 


Check out our Web site http://geo.arc.nasa.gov/sgg/AATS-website/ for display of selected results.
 

The retrieval algorithms are described in:

Russell, P. B., J. M. Livingston, E. G. Dutton, R. F. Puschel, J. A. Reagan,
T. E. Defoor, M. A. Box, D. Allen, P. Pilewski, B. M. Herman, S. A. Kinne, and 
D. J. Hofmann, 1993: "Pinatubo and Pre-Pinatubo Optical-Depth Spectra: Mauna Loa
Measurements, Comparisons, Inferred Particle Size Distributions, Radiative Effects,
and Relationship to Lidar Data". Journal of Geophysical Research, Vol. 98, No. D12,
22'969-22'985.

Schmid B., C. Mätzler, A. Heimo, and N. Kämpfer, 1997: 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.

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.

Schmid B., J.J. Michalsky, D.W. Slater, J.C. Barnard, R.N. Halthore, J.C. Liljegren,
B.N. Holben, T.F. Eck, J.M. Livingston, P.B. Russell, T. Ingold, and I. Slutsker.
Comparison of columnar water-vapor measurements from solar transmittance methods.
Applied Optics, Vol. 40, No. 12, 1886-1896 (2001).

Schmid B. et al., Coordinated airborne, space borne, and ground based measurements of 
massive, thick aerosol layers during the SAFARI-2000 Dry Season Campaign. 
(in preparation for SAFARI-2000 JGR special issue)



Point of contact:

Beat Schmid/Jens Redemann/Phil Russell/John Livingston
NASA Ames Research Center
MS 245-5
Moffett Field, CA 94035-1000

Phone: +1 650 604 5933
Fax:   +1 650 604 3625
e-mail: bschmid@mail.arc.nasa.gov
http://geo.arc.nasa.gov/sgg/AATS-website/