Data Products  › Product & Algorithm › Caveats of Snow Depth product
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Caveats for the standard products

Caveats of Snow Depth product

Algorithm development PI: Dr. Alfred T.C. Chang (NASA Goddard Space Flight Center)

This document briefly describes some caveats for the AMSR Level 2 standard products of snow depth.
Retrieval areas
This product retrieves snow depth (SD) over global land surfaces with the exception of the permanent land ice masses of Greenland and Antarctica. A land-sea mask is used to locate land areas and flag ocean and water bodies. A 'snow possible' mask is then used to detect terrestrial locations where snow accumulation is climatologically possible. The mask is derived from work of Dewey and Heim (1981 & 1983). All other terrestrial locations are flagged as 'snow impossible'.

Retrieval range and error
SD estimated for retrieval greater than 5.0 cm. Based on 2002-2003 winter AMSR-E data and 38 matched-up ground observations in the World Meteorological Organization Global Telecommunications System network the standard error is 24.2 cm. Further validation is underway.

Estimates in forested regions
Lower retrieval accuracies are known to exist in forested regions of the world where it is known that passive microwave retrievals underestimate the SD. A correction for this effect is under development for the algorithm. The Robinson and Kukla (1985) albedo data set will be used to identify forest cover and make the appropriate correction.

Estimates in mountainous terrain
The heterogeneity of SD over small scale lengths in mountainous terrain makes the retrievals in these locations uncertain.
Dewey, K.F. and R. Heim, Jr. (1981) Satellite observations of variation in Northern Hemisphere seasonal snow cover, NOAA Technical Report NESS 87, 83 pp.
Dewey K.F. and R. Heim, Jr. (1983) Satellite observations of variations in Southern Hemisphere snow cover, NOAA Technical Report NESDIS 1, 20 pp.
Robinson, D.A. and G. Kukla, (1985) Maximum surface albedo of seasonally snow covered lands in the Northern Hemisphere. Journal of Climate and Applied Meteorology 24: 402-411.