A New View of the Polar Regions from Space (Invited Presentation)

Over the past two years, new satellite sensors have begun viewing the polar regions with unprecedented spectral resolution and radiometric accuracy, promising to improve our ability to learn about and monitor high-latitude weather and climate. The Moderate Resolution Imaging Spectroradiometer (MODIS) is an advanced imager that measures upwelling visible and infrared radiation, and includes new channels that are sensitive to water vapor and carbon dioxide absorption. The Atmospheric Infrared Sounder (AIRS) measures the atmosphere at more than 2300 infrared wavelengths, drastically improving our ability to vertically resolve temperature and moisture structure. These and other new sensors are also important in that they will help define the capabilities of future weather satellite sensors of the National Polar-orbiting Operational Environmental Satellite System (NPOESS).

New products are currently under development with MODIS, AIRS, the Advanced Microwave Sounding Unit (AMSU), and other sensors. For example, MODIS data are being used to estimate high-latitude tropospheric winds by tracking clouds and water vapor features. These polar winds have been shown to have a significant positive impact on numerical weather forecasts in the polar regions and mid-latitudes. Low-level atmospheric temperature inversion strength and height are being estimated from MODIS, and comparisons to temperature profiles from AIRS are encouraging. New surface products have been developed recently; snow cover, ice extent, ice surface temperature, and snow albedo are now routinely generated.

But there are also new products from "old" sensors such as the Advanced Very High Resolution Radiometer (AVHRR) and the High Resolution Infrared Radiation Sounder (HIRS). NOAA satellites now provide us with over 20 years of data. While there are problems with inter-satellite calibration due to changes in sensor characteristics and orbital drift, some parameters can be examined in the context of climate change. Trends in satellite-derived surface temperature, albedo, cloud cover, radiation, and horizontal moisture and heat fluxes show promise in the study of climate change and feedback mechanisms.