Nonlinear Optimal Estimation of Temperature and Integrated Water Vapor and Liquid Using a Ground-based Microwave Radiometer in Coastal Winter Storms

B. E. Sheppard Atmospheric Environment Service, Downsview, Ontario

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R. E. Stewart Atmospheric Environment Service, Downsview, Ontario

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G. A. Isaac Atmospheric Environment Service, Downsview, Ontario

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T. B. Low KelResearch Corporation, Downsview, Ontario

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Abstract

Atmospheric temperature profiles and integrated water vapor and liquid are retrieved from ground-based microwave radiometric measurements using both nonlinear optimal estimation (NLOE) and statistical inversion (SI) methods. The results obtained from both methods are compared with collocated radiosonde observations during the Canadian Atlantic Storms Program field project in 1986. In general, the NLOE was superior to the SI method when clouds with high liquid water contents or when precipitation was present. Under these conditions, temperature profiles derived using NLOE had smaller root-mean-square differences from radiosonde observations than those retrieved using SI. Also, the overestimation of integrated vapor retrieved using the SI method was eliminated using the NLOE method. The radiometric observations were used in two case studies of winter cyclonic storms striking Atlantic Canada.

Abstract

Atmospheric temperature profiles and integrated water vapor and liquid are retrieved from ground-based microwave radiometric measurements using both nonlinear optimal estimation (NLOE) and statistical inversion (SI) methods. The results obtained from both methods are compared with collocated radiosonde observations during the Canadian Atlantic Storms Program field project in 1986. In general, the NLOE was superior to the SI method when clouds with high liquid water contents or when precipitation was present. Under these conditions, temperature profiles derived using NLOE had smaller root-mean-square differences from radiosonde observations than those retrieved using SI. Also, the overestimation of integrated vapor retrieved using the SI method was eliminated using the NLOE method. The radiometric observations were used in two case studies of winter cyclonic storms striking Atlantic Canada.

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