SeaWiFS Highlights July 2002 SeaWiFS Celebrates 5th Anniversary with the Fourth Global Reprocessing The SeaWiFS Project has just completed the reprocessing of the complete mission data set September 1997 through present) and is currently transferring all the refined data products to the Goddard DAAC for public distribution. Details of this reprocessing (the fourth one the SeaWiFS Project has undertaken) have been posted online at:. In order to make the most widely-used data products as readily available as possible during this transfer period, all the level-3 standard digital products in mapped and binned file formats, plus a few bonus products have been placed online at:. In the past three weeks over 600 gigabytes of data have been downloaded by researchers from around the world via this web site. In addition to the digital data, a complete set of global image products are also available online from the SeaWiFS web site for a large number of ocean, land and atmospheric parameters at weekly, monthly, seasonal, and annual timeframes. In the oceans, the regions with the lowest chlorophyll a concentrations are shown in purple (southeast Pacific Ocean) and deep blue, while the lighter blues, greens, yellows, and reds represent increasing phytoplankton abundance. On the land, the densely vegetated areas are the deepest green, the deserts are brown, and the white areas represent the snow covered regions of the world. POC: 970.2/Gene Feldman

SeaWiFS Celebrates 5th Anniversary with the Fourth Global Reprocessing Sydney Fall 1997–2001Winter 1997–2002 Spring 1998–2002Summer 1998–2001

The MODIS Snow and Sea Ice Products Dorothy K. Hall* Vincent V. Salomonson** George A. Riggs+ *Hydrological Sciences Branch, Code 974 **Earth Sciences Directorate, Code 900 +Science Systems and Applications, Inc. MODIS-derived snow and sea ice products, developed at Goddard, are available to order from the National Snow and Ice Data Center (NSIDC) where they are archived and distributed through the EOS Data Gateway (EDG). The MODIS snow products are available as daily (Figure 1) and 8-day composite maps at 500-m spatial resolution, and as daily and 8-day composite global climate-modeling grid (CMG) maps at 0.05º resolution (~5.6 km at the Equator) (Figures 2 & 3). The daily CMG maps provide percentage of snow cover in each pixel (also know as fractional snow cover) from % (Figure 4). Cloudcover is a problem with the daily maps, but very little cloudcover is left on the 8-day composite maps. The daily MODIS snow maps have been compared with NOAA operational snow maps at both 1-km and 25-km resolution. Results show an excellent correspondence among the maps, however there are differences. Available ground truth from higher-resolution satellite data (e.g., ETM+) and field work is used for validation when possible. Because the MODIS maps are derived from swath data, even ephemeral snow cover is mapped because often there are several swaths of data acquired of approximately the same area in one day. Sometimes the operational products miss this ephemeral snow cover because they are daily or near-daily maps, and they may miss snow cover that only stayed on the ground for a few hours. This ephemeral snow cover can cover very large areas especially at the edges of snow-covered areas during the fall in the Northern Hemisphere. The MODIS sea ice products are available as daily (Figure 5) products, and the 8-day composite products and the 0.05º-resolution CMG products for the north and south polar areas are in progress and should be available in the fall of The sea ice products map sea ice extent and sea ice surface temperature (IST). Preliminary validation of the IST from the product shows that the MODIS maps are within 1.5 K of the air temperature as measured using tide station air temperature data from Prudhoe Bay, Alaska. Additional validation using drifting buoy data is ongoing.

CLOUD LAND HUDSON BAY SNOW BLACK HILLS CANADA USA MODIS bands 1, 4, 3 SnowNon-snow Inland water Cloud Swath natural color (left) and snow product (right) - November 3, 2000 Fig. 1

Daily MODIS CMG Snow Map Fig. 2

March 6-13, 2002 Eight-Day Composite Global CMG MODIS Snow Map Fig. 3

40-50% 81-90% 51-60% %Not snow 61-70%71-80% Cloud The Daily CMG maps show fractional snow cover from % in each pixel Fig. 4

Comparison of IST from the MODIS Sea Ice Product with Air Temperature from Prudhoe Bay, AK cloud sea ice Prudhoe Bay 253.4K 21:35 UTC North Slope of Alaska cloud sea ice 254.4K Fig. 5