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Standard Measurements and Standard Data Sets for SHEBA |
SHEBA Project Office, PSC-APL/UW
dickm@apl.washington.edu
The Project Office made standard measurements at the SHEBA field experiment from October, 1997 to October, 1998 as follows: GPS RAWINSONDE profiles of pressure, temperature, humidity, wind speed and wind direction throughout the troposphere; time series of surface air pressure, temperature, humidity, wind speed, wind direction, incident shortwave irradiance and incident long wave irradiance at two meteorological towers; daily observations of precipitation amount using a precipitation gauge with a Nipher shield; 6-hourly weather reports using the Ship's Synoptic Code. In addition, we compiled a time series of ship's position and heading at four-hourly intervals, from the logbooks of the "Des Groseilliers".
The standard measurements have been corrected on the basis instrument calibrations performed before and after the experiment. Additional quality control was applied in the form of range checks and visual inspection of plots to identify bad data. The precipitation measurements were corrected for evaporation, wetting, and effects of wind speed on precipitation catch. The QC'd data have been compiled into standard data sets, and intercompared with other SHEBA data sets. The ship's position data set has been interpolated and differentiated to provide a sea ice velocity time series. Measurements of air pressure at the SHEBA station, and at surrounding buoys, are optimally analyzed to produce a two-dimensional field of sea level pressure and surface geostrophic wind in the study area.
The standard data sets are available through the SHEBA/JOSS CODIAC data management system.
Time series plots, time-height cross sections, maps, seasonal statistics and case studies are presented to summarize the data sets. The results indicate the dominant control on surface irradiance by variations in cloud cover; the strong correlations among ice velocity, surface wind and surface geostrophic wind; the correspondences between precipitation events and absolute humidity in the lower troposphere; and relationships between the "SHEBA year"and climatology in the study area.
