Geoscience Reference
In-Depth Information
9
Multiple Doppler Radar Analysis for Retrieving
the Three-Dimensional Wind Field Within
Thunderstorms
Shingo Shimizu
National Research Institute for Earth Science and Disaster Prevention/ Storm,
Flood, and Land-Slide Research Department
Japan
1. Introduction
Multiple Doppler radar analysis has been widely used to retrieve three-dimensional wind
fields within thunderstorms and meso-scale convective systems (MCS) since the late 1960s.
A number of countries have constructed dense operational radar networks, such as the
Operational Programme for the Exchange of Weather Radar Information (OPERA; Köck et
al., 2000), to monitor and forecast severe weather in metropolitan regions. Multiple Doppler
radar analysis using such operational radar networks improves 1) understanding of the
physical mechanisms behind heavy rainfall and severe wind, 2) detection and forecasting of
hazardous weather phenomena, and 3) planning for mitigation of human and
socioeconomic losses in metropolitan regions.
Early single Doppler radar measurements provided a basic understanding of storm
morphologies and their three-dimensional structures, including concepts for single-cell,
multicell, and supercell storms (Browning, 1964, 1965). Single Doppler radar observations can
only provide information on the radial component of wind (i.e., velocity which is directed
toward or away from the radar), rather than the full three-dimensional structure. Armijo (1969)
formulated a method that allowed the deduction of the three-dimensional wind structure by
combining the data from several Doppler radars. Improvements in this multiple Doppler radar
analysis method were reported during the 1970s and 1980s, including the design of optimal
radar networks (Ray et al., 1979, 1983), the development of alternative analysis schemes for
solving the mass continuity equation (Ray et al., 1980), and the introduction of floating
boundary conditions (Chong & Testud, 1983). These improvements were primarily motivated
by the need to overcome errors in the estimation of vertical velocity using upward integration
of the mass continuity equation (Doviak et al., 1976). Errors in estimates of vertical velocity
tend to amplify during such upward integration because of the stratification of density in the
atmosphere (Doviak et al., 1976; Ray et al., 1980). Theoretical demonstrations indicate that
downward integration of the mass continuity equation could yield more accurate estimates of
vertical velocity than those that can be obtained from upward integration (Ray et al., 1980).
Many subsequent studies have therefore applied downward integration schemes to determine
the three-dimensional structure of winds within severe storms (Kessinger et al., 1987;
Biggerstaff & Houze, 1991; Dowell & Bluestein, 1997).
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