NASA satellites (Figure 13) and numerous instruments provide high accuracy, stable, circum-Arctic measurements for ocean and sea ice observing, including surface vector winds over the ice-free ocean, sea surface temperature, marine phytoplankton and sea ice temperature. The NASA satellites and ocean and sea ice data sets include: 1. Passive microwave time series of sea ice extent begin in 1978 and are archived at NSIDC. 2. The major Synthetic Aperture Radar (SAR) time series is from the Canadian RADARSAT satellite launched in 1995. RADARSAT data of the Arctic Ocean are processed by the RGPS (RADARSAT Geophysical Processing System, yielding high-resolution charts of ice motion, age/thickness and deformation. All RGPS data are archived at the NASA-supported Alaska Satellite Facility (ASF), University of Alaska Fairbanks. 3. GRACE is a joint NASA/German mission that measures the changes in gravity associated with the changing mass of the ocean, land, and ice sheets. In experimental measurements, GRACE has measured the changes of mass associated with the shift of ocean currents in the Arctic Ocean. 4. The ICESat satellite is in a high latitude orbit (86°N) and can determine the free surface height of the Arctic Ocean up to that latitude. These laser measurements can be used to determine the geostrophic flow. ICESat also measures the height of the snow/air interface of the sea ice, which can be used to estimate sea ice thickness when combined with other data, e.g., snowfall and ice motion, or radar altimeter measurements of the sea ice freeboard. 5. Sea surface temperature (SST) and ice surface temperature (IST) are measured by NASA with the MODIS instrument aboard the Aqua and Terra satellites. The AMSR-E instrument on Aqua measures all-weather sea surface temperature. The follow-on instrument to MODIS is the Visible Infrared Imaging Radiometer Suite (VIIRS), scheduled for launch in 2010 on NPP (NPOESS Preparatory Project). The NPP follow-on satellite is the NPOESS (National Polar-orbiting Environmental Satellite System) series beginning in 2013. 6. Satellite-derived ocean color is used in combina-tion with environmental data to provide primary productivity. NASA currently provides ocean color from observations taken by the MODIS instrument on Aqua. Under present plans, the MODIS replacement is VIIRS on the NPP and NPOESS satellites. Because VIIRS on NPP is not expected to yield the same high quality of ocean color measurements as MODIS, there may be a gap in the high accuracy of these measurements.