This README file describes the format of the 14-channel Ames Airborne Tracking 

Sunphotometer (AATS-14) results obtained during ACE-Asia aboard the CIRPAS

Twin Otter.



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. 



We have computed fit coefficients for AOD 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. 





The exact format is described in the header of each file.



Note that:

AOD(13) expands to 13 variables (corresponding to the 13 wavelengths given in the header)

AOD_Error(13) expands to 13 variables  (corresponding to the 13 wavelengths given in the header)

fit_coeff expands to 3  variables  (as described above)



The files are pretty much self explanatory. But please do not hesitate to e-mail us for questions.





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 Relationsship to Lidar Data". Journal of Geophysical Research, Vol. 98, No. D12,

22'969-22'985.



Schmid B., C. MŠtzler, A. Heimo, and N. KŠmpfer, 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. Gass—, D. A. Hegg, E. …stršm, 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).







Point of contact:



Jens Redemann/ Beat Schmid/Phil Russell/John Livingston

NASA Ames Research Center

MS 245-5

Moffett Field, CA 94035-1000



Phone: +1 805 658-2637

Fax:   +1 805 658-2637

e-mail: jredemann@mail.arc.nasa.gov



Check out our Web site http://geo.arc.nasa.gov/sgg/AATS-website/ for regularly for updates.