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A method to combine spaceborne radar and radiometric observations of precipitation

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dc.contributor.authorMunchak, Stephen Joseph, author
dc.contributor.authorKummerow, Christian Detlef, advisor
dc.contributor.authorChandrasekhar, V., committee member
dc.contributor.authorRutledge, Steven A., committee member
dc.contributor.authorStephens, Graeme L., 1952-, committee member
dc.date.accessioned2007-01-03T04:51:02Z
dc.date.available2007-01-03T04:51:02Z
dc.date.issued2010
dc.description.abstractThis dissertation describes the development and application of a combined radar-radiometer rainfall retrieval algorithm for the Tropical Rainfall Measuring Mission (TRMM) satellite. A retrieval framework based upon optimal estimation theory is proposed wherein three parameters describing the raindrop size distribution (DSD), ice particle size distribution (PSD), and cloud water path (cLWP) are retrieved for each radar profile. The retrieved rainfall rate is found to be strongly sensitive to the a priori constraints in DSD and cLWP; thus, these parameters are tuned to match polarimetric radar estimates of rainfall near Kwajalein, Republic of Marshall Islands. An independent validation against gauge-tuned radar rainfall estimates at Melbourne, FL shows agreement within 2% which exceeds previous algorithms' ability to match rainfall at these two sites. The algorithm is then applied to two years of TRMM data over oceans to determine the sources of DSD variability. Three correlated sets of variables representing storm dynamics, background environment, and cloud microphysics are found to account for approximately 50% of the variability in the absolute and reflectivity-normalized median drop size. Structures of radar reflectivity are also identified and related to drop size, with these relationships being confirmed by ground-based polarimetric radar data from the North American Monsoon Experiment (NAME). Regional patterns of DSD and the sources of variability identified herein are also shown to be consistent with previous work documenting regional DSD properties. In particular, mid-latitude regions and tropical regions near land tend to have larger drops for a given reflectivity, whereas the smallest drops are found in the eastern Pacific Intertropical Convergence Zone. Due to properties of the DSD and rain water/cloud water partitioning that change with column water vapor, it is shown that increases in water vapor in a global warming scenario could lead to slight (1%) underestimates of a rainfall trends by radar but larger overestimates (5%) by radiometer algorithms. Further analyses are performed to compare tropical oceanic mean rainfall rates between the combined algorithm and other sources. The combined algorithm is 15% higher than the version 6 of the 2A25 radar-only algorithm and 6.6% higher than the Global Precipitation Climatology Project (GPCP) estimate for the same time-space domain. Despite being higher than these two sources, the combined total is not inconsistent with estimates of the other components of the energy budget given their uncertainties.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.identifierMunchak_colostate_0053A_10109.pdf
dc.identifierETDF2010100005ATMS
dc.identifier.urihttp://hdl.handle.net/10217/44767
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado State University. Libraries
dc.relation.ispartof2000-2019
dc.rightsCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.
dc.subjectTropical Rainfall Measuring Mission
dc.subjectTRMM
dc.subjectrain
dc.subjectradiometer
dc.subjectradar
dc.subjectprecipitation
dc.subjectmulti-sensor
dc.subject.lcshPrecipitation (Meteorology) -- Measurement
dc.subject.lcshRadiometers
dc.subject.lcshRain and rainfall -- Measurement
dc.titleA method to combine spaceborne radar and radiometric observations of precipitation
dc.typeText
dcterms.rights.dplaThis Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
thesis.degree.disciplineAtmospheric Science
thesis.degree.grantorColorado State University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy (Ph.D.)

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