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  • Author or Editor: J. G. Yoe x
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J. G. Yoe
,
M. F. Larsen
, and
E. J. Zipser

Abstract

Very high frequency (VHF) Doppler radar measurements of the horizontal and vertical winds are used to examine three procedures to extract mean profiles of horizontal and vertical winds. These are 1) time averaging of first-moment estimates of radial velocity from the high time resolution Doppler spectra; 2) time averaging of radial velocities estimated from a least-squares fitting of either one or two Gaussians to the spectra in order to account for the double peaks corresponding to turbulent and precipitation scattering that appear in the spectra during heavy rain; and 3) consensus averaging of the least-square-fitted radial velocities. Horizontal winds produced by these procedures were compared to each other and to those from two 5-cm radars operating nearby. Least-squares fitting yielded the best wind estimates, although a slight relaxation of the consensus criterion was sometimes found to be necessary in order to avoid the failure to find a consensus. The simple first-moment method produced comparable results, except below the melting level, where it performed more poorly. Vertical winds from the fitted VHF spectra were compared with those derived from the 5-cm-radar data using the extended velocity-azimuth display (VAD) technique. Reasonable agreement was found at heights above the freezing level.

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Wayman E. Baker
,
Robert Atlas
,
Carla Cardinali
,
Amy Clement
,
George D. Emmitt
,
Bruce M. Gentry
,
R. Michael Hardesty
,
Erland Källén
,
Michael J. Kavaya
,
Rolf Langland
,
Zaizhong Ma
,
Michiko Masutani
,
Will McCarty
,
R. Bradley Pierce
,
Zhaoxia Pu
,
Lars Peter Riishojgaard
,
James Ryan
,
Sara Tucker
,
Martin Weissmann
, and
James G. Yoe

The three-dimensional global wind field is the most important remaining measurement needed to accurately assess the dynamics of the atmosphere. Wind information in the tropics, high latitudes, and stratosphere is particularly deficient. Furthermore, only a small fraction of the atmosphere is sampled in terms of wind profiles. This limits our ability to optimally specify initial conditions for numerical weather prediction (NWP) models and our understanding of several key climate change issues.

Because of its extensive wind measurement heritage (since 1968) and especially the rapid recent technology advances, Doppler lidar has reached a level of maturity required for a space-based mission. The European Space Agency (ESA)'s Atmospheric Dynamics Mission Aeolus (ADM-Aeolus) Doppler wind lidar (DWL), now scheduled for launch in 2015, will be a major milestone.

This paper reviews the expected impact of DWL measurements on NWP and climate research, measurement concepts, and the recent advances in technology that will set the stage for space-based deployment. Forecast impact experiments with actual airborne DWL measurements collected over the North Atlantic in 2003 and assimilated into the European Centre for Medium-Range Weather Forecasts (ECMWF) operational model are a clear indication of the value of lidar-measured wind profiles. Airborne DWL measurements collected over the western Pacific in 2008 and assimilated into both the ECMWF and U.S. Navy operational models support the earlier findings.

These forecast impact experiments confirm observing system simulation experiments (OSSEs) conducted over the past 25–30 years. The addition of simulated DWL wind observations in recent OSSEs performed at the Joint Center for Satellite Data Assimilation (JCSDA) leads to a statistically significant increase in forecast skill.

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