Last update
9 Jul 2010
This page is maintained by
Mark Fielding
All content Copyright © The University of Reading unless otherwise stated.
Research
This page outlines the some of the work that has been done or is in progress in the Radar Group.
Note: the information on this page is rather old, and needs updating.
Cloud research
The main interest in clouds stems from their strong effect on the earth's radiation budget and hence their role in the climate system. Standard cloud observing instruments such as satellite-borne radiometers suffer from poor vertical resolution, but in recent years there has been growing interest in the use of millimetre-wave radar to make high vertical resolution measurements of clouds. A single radar can be used to determine the macroscopic properties of clouds (such as cloud cover and inhomogeneity), while combinations of active instruments can be used to derive microphysical properties (such as water content and particle size). These can be used to directly validate atmospheric models or to test algorithms that could be used by the proposed spaceborne cloud radar and lidar. The work is funded under the Cloud Characteristics project.
Comparison of ECMWF cloud cover
with radar-derived values. Deriving cloud overlap
statistics from radar. Quantifying
the effect of cirrus inhomogeneity on emissivity. Cirrus particle sizing using a
spaceborne radar and lidar. Dual-wavelength measurement of liquid
water content in stratocumulus. Dual-wavelength measurement of ice
water content in cirrus.Weather radar
The polarisation and Doppler capability of the Chilbolton 3-GHz radar, coupled with its very narrow beamwidth, make it an ideal tool with which to study the characteristics of precipitation. Much of the work is focussed towards improving the algorithms used by radars to measure rain rate for the purposes of flood forecasting. Radar also offers the possibility to distinguish between heavy rain and hail. Recent work has included: Observations of lightning and the effects of
electric fields on crystal alignment. Development of attenuation correction
algirithms at C-band using ZDR. Deriving raindrop shape versus size from
the consistency of the various polarimetric variables - fundamental
to many rain retrieval algorithms. Distinguishing between convective and
stratiform rain using vertical profiles of reflectivity - improves
rainrate measurements made by non-polarised radars. A case study in which oblate hail was
observed with a preferred fall mode - could have profound
implications for existing hail-detection algorithms.Mesoscale dynamics
When cloud or rain is present, the radars at Chilbolton can measure the velocity component along a line towards the antenna, which enables the wind field associated with mesoscale weather systems to be mapped out. The unique 1/4 degree beamwidth of the 3-GHz radar enables structure on much smaller scales to be resolved which is essential for measuring waves and convection.Preliminary results
Here we present images and preliminary analysis from experiments and new data acquisition systems.
Doppler
spectra in cirrus on 21 August 1998: mostly monomodal spectra Doppler
spectra in stratocumulus on 26 August 1998: bimodal spectra CWVC 1: 3D visualisation; velocity structure; model comparison Negative KDP as an
indicator of strong electric fields in thunderstorms
