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Surface and Cloud Conditions During SHEBA: Variability and Characteristics over the Western Arctic |
University of Colorado, NOAA, University of Colorado, University of Colorado, University of Colorado
james.maslanik@colorado.eduApplications of the SHEBA field observations for modeling depend in part on knowledge of the spatial and temporal variability of conditions over larger areas. For example, it would be useful to quantify the degree to which the SHEBA field data are representative of areas elsewhere in the Arctic, including the seasonal sea ice zone and areas that are affected by different types of air masses. Given the unusual climatic conditions encountered during SHEBA, it would also be beneficial to place conditions in the SHEBA year into the context of previous climate.
With this in mind, our work is focusing on: (a) combining satellite, aircraft and field data to characterize surface and cloud conditions over a large range of space scales, and (b) comparing the 1997-1998 conditions to conditions in previous years. The work presented here will summarize results primarily from the use of AVHRR, SSM/I and NCAR C-130 data sets. Comparisons of AVHRR-derived products to SHEBA measurements are used to gain further confidence in the satellite retrievals. A time series of twice-daily AVHRR products are then used to document conditions over the SHEBA single-column grid cell area for the 1997-1998 field period, and to contrast these conditions to those elsewhere in the western Arctic, and for other years. Surface information, including ice motion and lead coverages, are compared to SSM/I-derived ice concentration estimates to characterize the spatial and temporal variability in large-scale ice conditions. Surface and cloud conditions are compared to atmospheric pressure fieldds to illustrate relationships with variations in winds and temperature during the SHEBA period. Finally, the combined data sets are used to document sea ice and sea surface temperature conditions that may have contributed the large reductions in ice extent in summer 1998.
