NOAA AVHRR derived aerosol optical depth over land

Abstract

[1] Aerosol optical depth was retrieved from a time series of NOAA-16 AVHRR data from May 2001 through December 2002 for Central Europe (40.5°N-50.0°N, 0°E-17°E). In contrast to classical methods, no a priori knowledge of the surface reflectance is necessary, but instead the surface reflectance is estimated from a time series including the previous 44 days. Additionally, the area where aerosol optical depth can be retrieved is no longer limited to certain land cover types. Only bright surface targets are excluded in the retrieval. To retrieve the aerosol optical depth, the radiative transfer code SMAC is used. Afterwards the data are averaged within a 25 Â 25 pixel region to increase the retrieval precision. The resulting standard deviation of the aerosol optical depth within this region is used as a quality control parameter and suitable for a post-processing of the initial aerosol retrieval. This post-processing leads to a substantial increase in the retrieval accuracy when compared to ground-based AERONET measurements. Over 650 co-incident AVHRR retrievals and AERONET measurements were compared, and a correlation coefficient of 0.70 was found. Altogether, the proposed method offers the potential to generate an aerosol climatology based on NOAA AVHRR data, which dates back to the early 1980s.

Prediction of future hydrological regimes in poorly gauged high altitude basins: the case study of the upper Indus, Pakistan

“…Nowadays, SCA estimation from satellite data is widely adopted for water storage assessment in mountain areas, distributed modeling of snow cover and melting and hydrological and glaciological implications therein (Swamy and Brivio, 1996;Simpson et al, 1998;Cagnati et al, 2004;Hauser et al, 2005;Parajka and Blöschl, 2008;Georgievsky, 2009;Immerzeel et al, 2009). Unsupervised classification of SCA may be carried out based upon visible bands (Red, Green, Blue, RGB) and box type classification (Hall et al, 2003a, b;Hall et al, 2010, for estimation of SCA from MODIS® images), using digital number, DN > 200.…”

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

“…Meanwhile, the Seaviewing Wide Field-of-view Sensor (SEAWIFS) aboard GeoEye's OrbView-2 can provide AOD data over the globally ocean with a spatial resolution of 9 km × 9 km [18][19][20]. Long-term daily and monthly AOD records can also be obtained from the Advanced Very High Resolution Radiometer (AVHRR) aboard on TIROS-N and NOAA series with nadir spatial resolution of 1.1 km × 1.1 km [21][22][23][24]. Among all AOD products, the standard AOD products from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra and Aqua are the most widely used AOD products for the estimation of AOD, with spatial resolutions of 3 km and 10 km [3,[25][26][27].…”

Validation of a modified AVHRR aerosol optical depth retrieval algorithm over Central Europe

“…Knapp and Stowe (2002) derived τ a from the reduced resolution (110 × 110 km 2 ) Pathfinder-Atmosphere (PATMOS) data set using also bright surface targets. Hauser et al (2005a) applied a similar technique to derive τ a at full resolution (1.1 × 1.1 km 2 ) for Central Europe using NOAA-16 AVHRR and they further qualitatively compared monthly and seasonal means from this product with MODIS collection 004 data (Hauser et al, 2005b). A full resolution τ a climatology from AVHRR covering land surfaces is still missing.…”