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Titel |
Current status of Dual Ka-band radar field campaign in Japan for GPM/DPR mission |
VerfasserIn |
Yuki Kaneko, Katsuhiro Nakagawa, Masanori Nishikawa, Kenji Nakamura, Yasushi Fujiyoshi, Hiroshi Hanado, Haruya Minda, Kazuhide Yamamoto, Riko Oki, Kinji Furukawa |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250080890
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Zusammenfassung |
The Global Precipitation Measurement (GPM) mission is an expanded follow-on mission to
TRMM (Tropical Rainfall Measuring Mission) and a GPM core satellite will carry dual
frequency precipitation radar (DPR) and a GPM Microwave Imager on board. The DPR,
which is being developed by National Institute of Information and Communications
Technology (NICT) and Japan Aerospace Exploration Agency (JAXA), consists of
two radars; Ku-band precipitation radar (KuPR) and Ka-band radar (KaPR). The
DPR is expected to advance precipitation science by expanding the coverage of
observations to higher latitudes than those of the TRMM/PR, measuring snow and light
rain by the KaPR, and providing drop size distribution information based on the
differential attenuation of echoes at two frequencies. In order to secure the quality of
precipitation estimates, ground validation (GV) of satellite data and retrieval algorithms is
essential. Since end-to-end comparisons between instantaneous precipitation data
observed by satellite and ground-based instruments is not enough to improve the
algorithms.
The error of various physical parameters in the precipitation retrieval algorithms (e.g.
attenuation factor, drop size distribution, terminal velocity, density of the snow
particles, etc.) will be estimated by the comparison with the ground-based observation
data.
A dual Ka-band radar system is developed by the JAXA for the GPM/DPR algorithm
development. The dual Ka-radar system which consists of two identical Ka-band radars can
measure both the specific attenuation and the equivalent radar reflectivity at Ka-band. Those
parameters are important particularly for snow measurement.
Using the dual Ka-radar system along with other instruments, such as a polarimetric
precipitation radar, a wind-profiler radar, ground-based precipitation measurement systems,
the uncertainties of the parameters in the DPR algorithm can be reduced. The verification
of improvement of rain retrieval with the DPR algorithm is also included as an
objective.
Observations using the dual Ka-radar system were performed in Okinawa Island, in
Tsukuba, over the slope of Mt. Fuji, in Nagaoka, and in Sapporo, from 2011 to 2013. In
Okinawa Island, the performance of the measurement has been confirmed by rain
observation. In Tsukuba, one radar was directed in vertical and the other was in slant
direction. By this configuration, total attenuation in the melting layer was estimated. The
objective of the Mt. Fuji experiment was to observe the melting layer. The X-band
polarimetric radar was simultaneously operated. Unfortunately, the melting layer did not
come in between the two radars due to warm weather. In Nagaoka, much data on the wet
snow was obtained. In Sapporo, dry snow has been observed by dual Ka-radar with
meteorological instruments and other appliances.
Through those experiments the main results are the k - Ze relationships on various
precipitation types. The feasibility of total attenuation in melting layer has been
studied. Different k - Ze relationships have been obtained in snow observations. The
vertical variations of rainfall are also analyzed for the DPR algorithm development. |
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