Regional Trend Analysis of Satellite-Derived Snow Extent and Global Temperature Anomalies

The extent and variability of seasonal snow cover are important parameters in climate and hydrologic systems due to effects on energy and moisture budgets. Northern Hemisphere snow cover extent, comprising about 98 percent of global seasonal snow cover, is the largest single spatial component of the cryosphere, with a mean maximum extent of 47 million square kilometers (nearly 50 percent of the land surface area). During the past four decades, much important information on Northern Hemisphere snow extent has been provided by the NOAA weekly snow extent charts, derived from visible-band polar orbiting and geo-stationary satellite imagery. Since 1978, satellite passive microwave sensors have provided an independent source for snow monitoring, with the ability to penetrate clouds, provide data during darkness, and the potential to provide an index of snow water equivalent. We see both positive and negative trends in snow cover derived from these data sets, depending on region and time of year. We continue to search for attribution of these trends. We present regional trend analysis of both snow cover data sets, and comparisons with gridded temperature anomalies from the NASA GISS Surface Temperature Analysis data.