A Study of Near-Surface Winds in Marine Cyclones Using Multiple Satellite Sensors

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  • 1 Department of Atmospheric Sciences, University of Washington, Seattle, Washington
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Abstract

Synoptic-scale surface wind fields are developed using data from two Special Sensor Microwave/Imager (SSM/1) passive radiometers and the European Remote Sensing Satellite-1 (ERS-1) scatterometer for the lifetime of two northern Pacific winter storms. The data are merged with surface wind output from a planetary boundary layer (PBL) model. The inputs to the PBL model are from the European Centre for Medium-Range Weather Forecasts (ECMWF) global analyses. A method for interpolating these analyses to the time of the satellite passage, while preserving fundamental storm characteristics, was developed. Composite wind fields are constructed each time one or more of the satellites views the storms. These composite wind fields are compared to the near-surface wind fields from ECMWF analyses within the storm domain and to buoy wind data on a point-by-point basis. Comparison with ECMWF analyses shows that the composite winds are slightly higher and contain more mesoscale variability. Comparison with buoy data indicates that the composite winds are higher on average by 0.5 m s −1. However, there was a lack of buoy data in the high wind regime (greater than 15 m s−1). Comparisons between the various wind sources in the high wind regions of midlatitude storms show significant diversity.

Surface stress, divergence, vorticity, and air-sea heat flux fields are calculated using the composite winds. An example of the heat flux field associated with a midlatitude cyclone is shown, as well as the relationship between surface convergence and atmospheric water vapor.

Abstract

Synoptic-scale surface wind fields are developed using data from two Special Sensor Microwave/Imager (SSM/1) passive radiometers and the European Remote Sensing Satellite-1 (ERS-1) scatterometer for the lifetime of two northern Pacific winter storms. The data are merged with surface wind output from a planetary boundary layer (PBL) model. The inputs to the PBL model are from the European Centre for Medium-Range Weather Forecasts (ECMWF) global analyses. A method for interpolating these analyses to the time of the satellite passage, while preserving fundamental storm characteristics, was developed. Composite wind fields are constructed each time one or more of the satellites views the storms. These composite wind fields are compared to the near-surface wind fields from ECMWF analyses within the storm domain and to buoy wind data on a point-by-point basis. Comparison with ECMWF analyses shows that the composite winds are slightly higher and contain more mesoscale variability. Comparison with buoy data indicates that the composite winds are higher on average by 0.5 m s −1. However, there was a lack of buoy data in the high wind regime (greater than 15 m s−1). Comparisons between the various wind sources in the high wind regions of midlatitude storms show significant diversity.

Surface stress, divergence, vorticity, and air-sea heat flux fields are calculated using the composite winds. An example of the heat flux field associated with a midlatitude cyclone is shown, as well as the relationship between surface convergence and atmospheric water vapor.

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