Graduate Exam Abstract
Miguel B. GalvezPh.D. Preliminary
November 14, 2014, 1:00 pm - 3:00 pm
Morgan Library Rm. 172
Attenuation Correction of X-band Polarimetric Doppler Weather Radar Signals: Application to Systems with High Spatio-Temporal Resolution
Abstract: In the last decade the atmospheric science community has seen widespread and successful application of
X-band dual-polarization weather radars for measuring precipitation in the lowest 2 km of the troposphere.
These X-band radars have the advantage of a smaller footprint, lower cost, and improved detection of
hydrometeors due to increased range resolution. In recent years, the hydrology community began
incorporating these radars in novel applications to study the spatio-temporal variability of rainfall from
precipitation measurements near the ground, over watersheds of interest. The University of Iowa XPOL
radar system is one of the first to be used as an X-band polarimetric radar network dedicated to hydrology
studies. During the spring of 2013, the Iowa XPOL radars participated in NASA GPMâ€™s first field campaign
focused solely on hydrology studies, called the Iowa Flood Studies (IFloodS).
Weather radars operating in the 3.2 cm (X-band) regime can suffer from severe attenuation, particularly
during heavy convective storms. This has led to the development of sophisticated algorithms for X-band
radars to correct the meteorological observables for attenuation. This is especially important for higher
resolution hydrology-specific X-band weather radars, where the attenuation correction aspect remains
relatively unexamined. This research studies the problem of correcting for precipitation-induced attenuation
in X-band polarimetric weather radars with high spatio-temporal resolution. We developed a modified ZPHI
attenuation correction algorithm, with a differential phase constraint, and tuned it for the high resolution
IFloodS data obtained by the Iowa XPOL-4 radar. Although this algorithm has good performance in pure rain
events, it is difficult to fully correct for attenuation and differential attenuation near the melting layer where a
mixed phase of rain and melting graupel exists. This research proposes to also investigate dual-wavelength
algorithms to separately estimate the path integrated attenuation due to rain and wet ice in the region near
the melting layer. We propose to use data from the dual-frequency, dual-polarization CHILL S-/X-band
Doppler weather radar for this analysis.
Adviser: V. N. Bringi
Co-Adviser: Jose G. Colom
Non-ECE Member: Paul Mielke
Member 3: Ali Pezeshki
Addional Members: Branislav Notaros
Mishra, K. V., W. F. Krajewski, R. Goska, D. Ceynar, B. Seo, A. Kruger, J. Niemeier, M. B. Galvez, V. N. Bringi, L. Tolstoy, â€œDeployment and performance analyses of high-resolution Iowa XPOL radar system during NASA IFloodS campaign,â€ Manuscript under preparation (to be submitted to AMS Journals), 2014.
Krajewski, W. F., K. V. Mishra, M. B. Galvez, R. Goska, M. Thurai, V. N. Bringi, L. Tolstoy, A. Kruger, and W. A. Petersen, â€œSalient observations and performance evaluation of Iowa XPOL radars during the NASA GPM IFloodS campaign,â€ AGU Fall Meeting, San Francisco, CA, 2014.
Mishra, K. V., W. F. Krajewski, R. Goska, D. Ceynar, A. Kruger, M. Galvez, and V. N. Bringi, â€œIowa X-band polarimetric radar data analyses: A selection of cases from IFloodS,â€ 7th Precipitation Measurement Missions (PMM) Science Team Meeting, Baltimore, MD, August 4-8, 2014.
Galvez, M. B., J. G. Colom, V. Chandrasekar, F. Junyent, S. Cruz-Pol, R. A. Rodriguez Solis, L. Leon, J. J. Rosario-Colon, B. De Jesus, J. A. Ortiz, K. M. Mora Navarro, â€œFirst observations of the initial radar node in the Puerto Rico TropiNet X-band polarimetric Doppler weather testbed,â€ IGARSS, 2013.
Galvez, M. B., J. G. Colom, V. Chandrasekar, F. Junyent, S. Cruz-Pol, R. A. Rodriguez Solis, Ki-Ryong Kwon, â€œFirst Observations of an X-Band dual polarization Doppler weather radar on the western coast of Puerto Rico,â€ IGARSS, 2011.
Galvez, M. B., J. G. Colom, V. Chandrasekar, F. Junyent, S. Cruz-Pol, R. A. Rodriguez Solis, â€œSalient Features of the Radar Nodes in the Puerto Rico Tropical Weather Testbed,â€ IGARSS, 2009.
Program of Study: