Graduate Exam Abstract

Miguel B. Galvez

Ph.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 GPM’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, “Deployment and performance analyses of high-resolution Iowa XPOL radar system during NASA IFloodS campaign,” 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, “Salient observations and performance evaluation of Iowa XPOL radars during the NASA GPM IFloodS campaign,” 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, “Iowa X-band polarimetric radar data analyses: A selection of cases from IFloodS,” 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, “First observations of the initial radar node in the Puerto Rico TropiNet X-band polarimetric Doppler weather testbed,” IGARSS, 2013.

Galvez, M. B., J. G. Colom, V. Chandrasekar, F. Junyent, S. Cruz-Pol, R. A. Rodriguez Solis, Ki-Ryong Kwon, “First Observations of an X-Band dual polarization Doppler weather radar on the western coast of Puerto Rico,” IGARSS, 2011.

Galvez, M. B., J. G. Colom, V. Chandrasekar, F. Junyent, S. Cruz-Pol, R. A. Rodriguez Solis, “Salient Features of the Radar Nodes in the Puerto Rico Tropical Weather Testbed,” IGARSS, 2009.

Program of Study:
ATS 606
ECE 501
ECE 513
ECE 514
ECE 530
ECE 742
ECE 752
ECE 799