Weather influence on passive microwave brightness temperatures

  • Stig M. Løvås
  • Irene Rubinstein
  • Christian Ulstad

Abstract

Sea ice charts produced using spacebornc passive microwave observations are used on routine basis at several ice forecasting centres and during sea ice research campaigns. The capability of passive microwave sensors to monitor the earth, regardless of cloud cover or daylight, and the 1400 km swath width (SSM/I) make these sensors well suited not only for ice forecasting but also for providing information needed for planning northern oceanic routes. The retrieval of sea ice parameters is carried out by utilizing 37 and 19 GHz brightness temperatures measured by Special Sensor Microwave Imager (SSM/I) on the Defense Meteorological Satellite Program (DMSP) platform. The ice type identification uses a-priory established signature brightness temperatures for each ice type. The algorithm generating the sea ice information contains some climatological information on the weather dependence of the observed brightness temperature. A comparison between passive microwave (SSM/I) retrieved ice parameters and ice maps from the Norwegian Meteorological Institute (DNMI) indicates that the weather correcting procedure within the algorithm may need regionalized input. The correlation of variability of the observed brightness temperatures with the weather changes has to be derived prior to introducing any corrections to the existing algorithms. The observed brightness temperatures contain information not only about the ice surface but also the atmospheric contribution. One of the crucial tasks is to establish a technique for flagging changes on the ice surface in order to segregate them from the atmospheric influence on the passive microwave signal. To obtain more knowledge about the effects of regional weather on the retrieval of sea ice parameters, local climatological information from DNMI has been compared with the SSM/I ice charts. This paper focuses on the outcome of this comparison and how regional atmospheric information can be used in the retrieval of sea ice information from passive microwave data.

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Published
1994-01-06
How to Cite
Løvås S. M., Rubinstein I., & Ulstad C. (1994). Weather influence on passive microwave brightness temperatures. Polar Research, 13(1), 67-81. https://doi.org/10.3402/polar.v13i1.6682