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NIM-AOD

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Browse and Order ARM AMF Niamey Aerosol Optical Depth Data

Niamey Aerosol Optical Depth (AOD)

MFRSR irradiance data collected during the ACRF AMF deployment in Niamey, Niger have been used to derive AOD for five wavelength channels of the MFRSR. The AOD data extends from November 2005 through January 2007. These data have been corrected to adjust for filter drift over the course of the campaign and contamination due to forward scattering as a result of large dust particles in the atmosphere around Niamey.

An examination of the daily averaged AODs at 500 nm reveals several interesting features. The first of these is the presence of very large AODs (> 2), of several days duration. Such spikes occurred several times during the year-long campaign. One of these cases occurred in early March, and is indicative of an intense dust storm, which was intensely studied by ARM researchers (Slingo et al., 2006). The time series of Angstrom exponent indicates that the exponent exhibits seasonal variability, being largest during December through February (cool, dry season) and smallest during the second quarter of the year, April through June.

Data Description

daily-average-aod.asc
This summary data file contains daily averaged aerosol optical depths from the MFRSR at wavelengths of 415 nm, 500 nm, 615 nm, 673 nm, and 870 nm and a daily averaged angstrom exponent.

The daily-average-aod.asc file contains eight columns of data as follows:
(1) date, fractional year (in LST = UTC + 1 hr)
(2) day of year, Jan. 1 = 1
(3-7) corrected AODs (415, 500, 615, 673, 870 nm)
(8) Angstrom (500/870)

References

Michalsky, JJ , JA Schlemmer, WE Berkheiser, JL Berndt, LC Harrison, NS Laulainen, NR Larson, and JC Barnard. 2001. "Multiyear measurements of aerosol optical depth in the Atmospheric Radiation Measurement and Quantitative Links programs." J. Geophys. Res. 106: 12,099.

Russell, PB, JM Livingston, O Dubovik, SA Ramirez, J Wang, J Redemann, B Schmid, M Box and BN Holben. 2004. "Sunlight transmission through desert dust and marine aerosols: Diffuse light corrections to Sun photometry and pyrheliometery." J. Geophys. Res., 109, D08207, doi:10.1029/2003JD004292.

Slingo. A, TP Ackerman, RP Allan, EI Kassianov, SA McFarlane, GJ Robinson, JC Barnard, M Miller, JE Harries, JE Russell, and S. Dewitte. 2006. "Observations of the impact of a major Saharan dust storm on the atmospheric radiation budget." Geophysical Research Letters, 33, L24817, doi:10.1029/2006GL027869.

Contact Information

Connor Flynn
connor.flynn@pnl.gov
509-375-2041

Jim Barnard
james.barnard@pnl.gov
509-372-6145

Evgueni Kassianov
Evgueni.Kassianov@pnl.gov
509-372-6535