Chapter 13
Ground-Based Remote Sensing of
Cloud Properties Using
Millimeter-Wave Radar
Eugene E. Clothiaux, T.P. Ackerman and David M. Babb
Department of Meteorology, Pennsylvania State University
502 Walker Building, University Park, PA 16802
United States of America
Abstract
The elements of radar signal processing are described in the context of climate applications
of radar. To this end descriptions of radar hardware are minimized and emphasis is placed
on describing the transformation of the radar signal as it propagates from the transmitter up
into the atmosphere and then back to the radar receiver after a scattering event. For the final
radar observables to be of use to the climate community, they must be turned into quantitative
measures of the location and properties of clouds. Descriptions of recent algorithm development efforts are described to illustrate approaches and techniques that are being developed to
accomplish the goal of producing quantitative descriptions of cloud properties from the radar
observables.
13.1 Introduction
The importance of clouds to the present climate of the Earth is unquestioned. As the Earth
system undergoes change, both natural and human-induced, the physical properties of clouds
can be expected to change. To understand the current role of clouds in the climate system, as
well as possible roles in future climate systems, observation of the current cloud fields and their
evolution in time is necessary. Unfortunately, even some of the most basic features of clouds,
such as their frequency of occurrence or geometrical thickness, are difficult to determine. Recent
satellite observational studies, such as the International Satellite Cloud Climatology Project,
are leading to a significant improvement in understanding the horizontal distribution of clouds;
however, these kinds of satellite analyses are only beginning to address the issue of the vertical
distribution of the observed cloud fields. With the technologies currently available, the most
NATO AS! Series, Vol.! 45
Radiation and Water in the Climate System:
Remote Measurements
Edited by Ehrhard Raschke
e Springer-Verlag Berlin Heidelberg 1996
Ground-Based Remote Sensing of
Cloud Properties Using
Millimeter-Wave Radar
Eugene E. Clothiaux, T.P. Ackerman and David M. Babb
Department of Meteorology, Pennsylvania State University
502 Walker Building, University Park, PA 16802
United States of America
Abstract
The elements of radar signal processing are described in the context of climate applications
of radar. To this end descriptions of radar hardware are minimized and emphasis is placed
on describing the transformation of the radar signal as it propagates from the transmitter up
into the atmosphere and then back to the radar receiver after a scattering event. For the final
radar observables to be of use to the climate community, they must be turned into quantitative
measures of the location and properties of clouds. Descriptions of recent algorithm development efforts are described to illustrate approaches and techniques that are being developed to
accomplish the goal of producing quantitative descriptions of cloud properties from the radar
observables.
13.1 Introduction
The importance of clouds to the present climate of the Earth is unquestioned. As the Earth
system undergoes change, both natural and human-induced, the physical properties of clouds
can be expected to change. To understand the current role of clouds in the climate system, as
well as possible roles in future climate systems, observation of the current cloud fields and their
evolution in time is necessary. Unfortunately, even some of the most basic features of clouds,
such as their frequency of occurrence or geometrical thickness, are difficult to determine. Recent
satellite observational studies, such as the International Satellite Cloud Climatology Project,
are leading to a significant improvement in understanding the horizontal distribution of clouds;
however, these kinds of satellite analyses are only beginning to address the issue of the vertical
distribution of the observed cloud fields. With the technologies currently available, the most
NATO AS! Series, Vol.! 45
Radiation and Water in the Climate System:
Remote Measurements
Edited by Ehrhard Raschke
e Springer-Verlag Berlin Heidelberg 1996