Enhancing NASA's Contributions to Polar Science A Review of Polar Geophysical Data Sets (2001) / Chapter Skim
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Executive Summary
Executive Summary
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These raw data are compiled and processed into products, or data sets, useful to scientists. These so-called "polar geophysical data sets" can then be studied and interpreted to answer questions related to atmosphere and climate, ice sheets, terrestrial systems, sea ice, ocean processes, and many other Phenomena in the cryosphere.
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" and "What are the spatial and temporal distributions and variability of aerosols in the polar atmosphere? " The third question, focused on responses to change, breaks down into a number of important questions, such as "How will the atmospheric contribution to the mass balance of ice sheets change with the effects of
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," "How will the albedo-temperature feedback amplify future climate change? ," and "How will land surface hydrology and energy exchanges be influenced by the climate-induced changes to vegetation structure and distribution across the polar regions?
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Measurement Requirements 1.2a: Ice sheet elevation time series. Measurement Requirements 1.2b: Time series of ice velocity and grounding line position, ice thickness distributions for outlet glaciers and drainage basins, surface energy balance, albedo, and ice-melt runoff.
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Measurement Requirements 2.1: Sea ice concentration and extent, evapotranspiration, soil moisture, surface temperature, permafrost characteristics, vegetation characteristics, disturbance characteristics, wetland extent, CO2 and CH4 fluxes, nitrogen deposition, river discharge, and chemistry. continued
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Measurement Requirements 3.3a: Surface albedo, sea ice concentration and thickness, melt pond fraction, snow depth on sea ice, surface temperature. Measurement Requirements 3.3b: Atmospheric temperature and humidity profiles, aerosols, surface temperature and albedo, cloud horizontal/vertical extents and water contents (particle size and phase)
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in high latitudes? Measurement Requirements 4.1: Permafrost extent, thermokarst topography, soil temperature profile, land-surface temperature, snow characteristics, soil moisture, vegetation characteristics, disturbance characteristics, wetlands extent.
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Measurement Requirements 4.4: Sea level height, sea ice concentration, coastal erosion rates, coastal topography. Measurement Requirements 4.5: Permafrost characteristics, vegetation characteristics, rainfall, snowfall, snow characteristics, disturbance characteristics, wetlands extent, soil moisture, land surface temperature, photosynthetically active radiation, evapotranspiration, vegetation characteristics, sea ice extent and thickness, sea surface temperature, salinity, and color, UV radiation.
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The committee's analysis identified the following priority measurement needs: atmospheric profiles (including vertical profiles of atmospheric temperature, humidity, and wind) cloud properties aerosol properties surface temperature surface heat fluxes surface albedo precipitation permafrost land surface characteristics evapotranspiration soil moisture terrestrial CO2 and CH4 flux river runoff ice sheet elevation ice sheet dynamics snow cover sea ice concentration sea ice thickness sea ice velocity ocean surface temperature and salinity sea surface height ocean productivity and CO2 flux wildlife habitat and migration NASA makes significant contributions to the development, evaluation, and availability of many data sets of importance in addressing the science-driving questions.
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These high priority measurement needs are: · polar precipitation, · surface albedo, · freshwater discharge from terrestrial regions, · surface temperature, · surface turbulent fluxes, · permafrost extent, · ocean surface salinity, · ice sheet mass flux, · land surface characteristics, and · sea ice thickness. For all variables, the need is for data sets sufficient to determine the spatial and temporal variations.
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Related to freshwater discharge from terrestrial regions, there is need for data on fluxes of freshwater to polar oceans from ice sheets and glaciers, as well as surface and sub-surface runoff from non-glaciated land area. With regard to surface temperature, the need for routine measurements under cloudy skies calls for multisensor analysis approaches that combine microwave, infrared, and radar measurements.
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This interaction can occur to some extent through data assimilation activities; however, there is often a disconnect between modelers' needs for forcing and validation data sets and the products derived from remote sensing. The committee recommends that NASA strengthen the connection between modeling and its remote sensing strategy for the polar regions.
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Improving the Effectiveness of Distributed Active Archive Centers As a result of its deliberations including consideration of the 1998 National Research Council report, Review of NASA's Distributed Active Archive Centers, conversations with DAAC managers and representatives of associated user groups, and a survey of the science community the committee learned much about the effectiveness of the polar-oriented DAACs. Unlike the recommendations in the two preceding sections, the following recommendations pertain specifically to the polar DAACs.
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The addition of browse products to data sets would help users unfamiliar with the data to judge the utility of the data set for their uses. To help overcome obstacles faced when trying to combine data sets from different sensors, data set providers should increase availability of userfriendly software tools to help with tasks such as converting from one format to another and among standard grid formats.
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