Research Associate Professor, Atmospheric Sciences
University of Utah
135 S 1460 East Rm 819 (WBB)
Salt Lake City, Ut 84112-0110
2003 Atmospheric Sciences University of Wyoming
2000 Atmospheric Sciences University of Wyoming
On the diurnal variations of global thunderstorms and the global atmospheric electrical circui (Journal Article), 2010
"Warm rain" in the tropics: Seasonal and regional distribution based on 9 years of TRMM data (Journal Article), 2009
Implication of the day vs. night differences of water vapor, carbon monoxide and thin cloud observations near tropical tropopause (Journal Article), 2009
A cloud and precipitation feature database from 9 years of TRMM observations (Journal Article), 2008
Diurnal cycles of precipitation, clouds, and lightning in the triopics from 9 years of TRMM observations (Journal Article), 2008
Implications of the differences between daytime and nighttime CloudSat observations over the tropics (Journal Article), 2008
Geographical and seasonal distribution of tropical tropopause thin clouds and their relation to deep convection and water vapor viewed from satellite measurements (Journal Article), 2007
Global distribution of tropical deep convection: Different perspectives using infrared and radar as the primary data source (Journal Article), 2007
How do the water vapor and carbon monoxide tape recorders start near the tropical tropopause? (Journal Article), 2007
Global precipitation survey using remote sensing techniques (Radars & Satellites)
Research Keywords, Regions of Interest and Languages:
Population of precipitation systems from TRMM [details]
The objective of this project is to provide a long-term, homogeneous record of occurrence of precipitation systems categorized by their properties observed by space-borne radars and passive microwave radiometers (since 1998). By cataloging precipitation systems by individual event, specifically including scale, we will provide powerful tools to easily search and sort the weather systems observed over the past decade by their time, location, size, rain volume and proxies for convective intensity. These products are directly responsive to the need to describe the role of precipitation in the climate system, with emphasis on change not just in the mean, but in the variance. That is, what fraction of precipitation comes from intense events, and how is that fraction changing?
The principal algorithm to produce the proposed products is the Precipitation Feature (PF) algorithm. Its unique feature is to define PFs by grouping contiguous raining area observed by the TRMM Precipitation Radar (PR) and Microwave Imager (TMI). The properties of each PF, such as size, rain volume, and the convective intensity proxies (e.g., lightning flash rate, height of radar echoes) are summarized. With a database of PFs defined from 10 years TRMM observations, we analyze the global distribution of extremely intense convective storms, some of which penetrate the tropical tropopause, and properties of PFs with and without lightning. Since TRMM only covers tropical and subtropical regions, we plan to generate the PFs from TRMM 3B42 dataset to provide a set of product with global coverage. The properties of each 3B42 PF, such as size, rain volume will be summarized and categorized same as TRMM PFs. It is well established that the population of extremely intense storms is distinctly different from the population of extremely rainy storms. We propose to produce global distribution of occurrence of PFs with different size and intensities and their rainfall contribution from this database.
We will maintain a user-friendly online-access of the above products. Users will be able to access the data and quick-look maps, statistics and time series of global distribution of population and precipitation contribution by the TRMM PFs and 3B42 PFs (annually and seasonally) categorized by their sizes and intensities. A web tool will provide functions to search, sort and view the most intense or rainiest storms observed since 1998. In this way, we will provide an extension of PPS
Project Web Site:trmm.chpc.utah.edu/
Population of precipitation systems observed by space-borne radar and microwave radiometers: NASA 2008
Quantitative comparison and diagnostic evaluation [details]
Evaluation of precipitation algorithms in different meteorological regimes helps understanding the different performances of algorithm and their relation to the different microphysical processes. In a long run, based on the knowledge of these performances, a rainfall adjusting algorithm may be developed to improve rainfall retrieval based on the regimes defined based on the properties of precipitation system , such as size, intensity, and regimes etc.
University of Utah Precipitation Feature (PF) is becoming a useful tool in the TRMM science and public community. At the moment, University of Utah PF database is well maintained and open to the public through a website supported by a non-solicited NASA grant. With the upcoming reprocessing of Version-7 data (or GPM version 1.0), the database will need to be reprocessed. Some parameters will need to be added or fixed with needs. Current planed ongoing and upcoming tasks of applying this database include:
1) Adding the latent heating parameters to PFs.
2) Collaboration with Dr. Iguchi on validation of Version 7 PR 2A25 algorithm.
3) Continued collaboration with Dr. Nai-Yu Wang on developing the 2A12 land algorithm.
4) Continued collaboration with Dr. Xiaowen Li (Tao s group) on her study of improving the bin-model.
5) Creation of the tropical cyclone precipitation feature database.
Project Web Site:trmm.chpc.utah.edu/
Vertical transport of aerosols and trace gases thr [details]
The objective of this research is to improve the fundamental understanding of the troposphere-stratosphere exchange over tropics and subtropics, focusing on the role of deep convection in aerosol and trace gases vertical transport through tropopause over tropics and subtropics.
The principal set of tools have been developed and will be used in this project include the CloudSat/CALIPSO Cloud Feature (CF) database and the TRMM Precipitation Feature (PF) database. The unique features of these databases are that every CF or PF is first defined by using a contiguity test so that we know the size and intensity of each one, then assign many other observed properties. Using these databases, we have discovered that CloudSat and CALIPSO have observed clouds with different properties between day and night overpasses. The diurnal cycles of convection and cold clouds from using TRMM PF database provide an insightful guidance to physically interpret these differences (Liu et al. 2008; Liu and Zipser, 2009).
To understand the vertical transport of aerosol and trace gases, it is especially important to relate the transport to the life cycle and properties of deep convection. This proposal aims at using the CF and PF databases to analyze the relations among the observed aerosols, trace gases and the properties of convection as a function of day vs. night, for example, vertical transport of aerosols and CO from biomass burning by strong deep convection over Africa.
PI has studied the seasonal variations of deep convection from TRMM, CO and water vapor from AURA MLS, and interpreted the CO and Water tape recorders by deep convection vertical transport and tropopause temperature (Liu et al. 2007). This proposal will continue to expand the existing research to diurnal scale. First, the CALIPSO aerosol data and AURA MLS CO and water vapor data will be collocated with CloudSat/CALIPSO CFs so that each CF will have collocated properties of aerosol, CO and water vapor. These properties will be compared for day and night and will be related to the CF convective intensity properties. The diurnal cycles from TRMM will be used to help interpreting these results. Using the collocated dataset, we will focus on the following research topics:
Evaluation of the regional differences of aerosol, CO and water vapor transport contributed by the deep convection vs. by large scale ascent by comparing their concentration differences in the lower stratosphere and upper troposphere under deep convection, thin cloud, and clear conditions.
Investigating extreme high and low values of aerosol, CO and water vapor concentrations in the upper troposphere and lower stratosphere over the tropics and subtropics and their relation to the collocated deep convection, thin cloud events and environments from NCEP reanalysis.
This research fits into the first item of the announcement:
Phenomenological study of fundamental cloud and aerosol processes and evolution, as well as aerosol vertical transport; including stratospheric exchange.