Research

Field Campaigns

Our group actively participates in field campaigns around the world. Recent examples include NASA GPM satellite validation campaigns across the US, the HS3 and GRIP tropical cyclone campaigns, the HAIC-HIWC project in Darwin, Australia and Cayenne, French Guiana, the NASA-supported CPEX campaign in the AtlanticĀ  and Gulf of Mexico, and the DOE-supported CACTI and NSF-supported RELAMPAGO campaigns in Argentina. Dr. Varble was the PI of CACTI while former group member Steve Nesbitt was the PI for RELAMPAGO. Dr. Zipser, and graduate students Mani Rajagopal andĀ  Zhixiao Zhang participated in the RELAMPAGO field campaign. Upcoming field campaigns include the NASA-supported CPEX-AW field campaign based in Cape Verde. Dr. Zipser is a lead mission scientist for this campaign. Post-Docs James Russell and Peter Veals, and graduate student Mani Rajagopal will also be participating. The goal of CPEX-AW is to obtain detailed measurements of tropical oceanic convection and the associated environments, while also collaborating with a multi-national European research team to validate the ESA’s Aeolus satellite – a space-borne lidar that measures winds and aerosols.

Convective Precipitation Systems and Environments

Research funded by NASA has focused on characterizing the properties of deep convective systems around the world using radar and radiometer data from the TRMM and GPM satellites, and the University of Utah TRMM/GPM Precipitation Feature Database. Extreme storms, from convective intensity, rain rate, and size perspectives, are a particular focus because of their impact on society. We are working to better understand their connection to large-scale environmental thermodynamic and kinematic conditions, processes that organize scatter storms into contiguous large systems that produce more lightning and are longer lived, and whether retrievals of their properties by satellite are biased by assumptions made in retrieval algorithms.

Aerosol-Convection Interactions

Research funded by DOE focuses on the affect environmental aerosols have on the properties and intensity of convection. In the past, our group has statistically examined the role aerosols play on the intensity of convection at the DOE Southern Great Plains site while taking into account the various meteorological conditions present. We are currently conducting a similar examination of aerosol-convection interactions, taking into account the observed meteorological conditions, using data from recent joint DOE and NSF field campaigns in Argentina – CACTI and RELAMPAGO. These field campaigns provided an excellent opportunity to examine such interactions due to the long time-series (7 months) of aerosol and radar observations, as well as the abundance of convection in the observed region, and the variability of aerosol conditions across this time period.

High Resolution Model Evaluation and Improvement

Research funded by DOE has focused on evaluating and improving high-resolution simulations of deep convective systems around the world by using in situ and remote sensing measurements from field campaigns. Previous work has established significant biases in both convective intensity and parameterizations of cloud particle properties and microphysical processes. Recent work has focused on the impacts of model resolution and microphysics representation on feedbacks between precipitation, cold pools, and mesoscale inflows and outflows that significantly impact system evolution, while the impact of newly developing novel microphysics parameterization methods on convective clouds are also being tested.

High Ice Water Content Production and Detection

Research funding from NSF has led to a better understanding of high ice water content regions with low radar reflectivity in deep convective cloud systems that can present hazards to commercial aircraft. Our research aims to improve detection and methods of avoidance of these regions. It also involves identifying the cloud processes that produce these regions of numerous, small ice particles and improving their representation in models. Additionally, since 2006, our group has worked with the commercial aircraft radar division of Rockwell Collins, Inc., using the University of Utah Precipitation Feature database and our understanding of the variability of deep convective system properties around the world to assist them in designing their aircraft radar displays to adjust to this variability, better informing pilots of potential hazards.

Tropical Cyclone Intensification

Research funded by NASA focuses on improving our understanding of the processes that differentiate between tropical cyclones that intense hurricanes versus those that remain modest in intensity. Using aircraft and satellite datasets with high-resolution ensemble model simulations, a hypothesis that increased symmetry in rainfall around the center of the cyclone is a key factor in this determination is being tested, along with the potential that it is more important than the intensity of the deep convection in the cyclone.