Image courtesy Ms. Yu (Jade) Wang

Evaluating the Effects of Land Surface Conditions on Rainfall Patterns of Modeled Landfalling Tropical Cyclones Using Geospatial Methods

Speaker: Ms. Yu (Jade) Wang

PhD Candidate, Department of Geography, University of Florida

Thursday, April 18, 2019

2:50-3:50 PM (Period 8)

Turlington Hall Room 3012

University of Florida

All are welcome to attend.

Tropical Cyclone Idai Aims at Mozambique. Terra-MODIS image credit NASA Earth Observatory

The March12th NASA Earth Observatory Image of the Day was a Terra-MODIS image of Tropical Cyclone Idai, preparing to make landfall on Mozamique.

For help interpreting the image, NASA asked UF Geography Professor Dr. Corene Matyas to explain what was in the image:

“Several cyclones in the past have started over Mozambique and then moved over water and intensified into more organized systems, although this type of situation is not common,” said Corene Matyas, a researcher at University of Florida who has studied cyclones in this area. It is relatively common, however, to see cyclone tracks in the Mozambique Channel that meander and loop, due to weak steering currents.

Cyclones that form in the channel tend to be weaker than those that form over the Southwest Indian Ocean, north and east of Madagascar. But Matyas points out that regardless of where a cyclone forms, some have reached their highest intensity within a day before landfall. Tropical Cyclone Eline in February 2000, for example, passed over Madagascar and the Mozambique Channel, and then quickly intensified just before landfall in Mozambique.

“Keys to intensification are warm ocean waters to sufficient depth, the absence of strong winds in the upper troposphere, and being contained inside of a moist air mass,” Matyas said. “These conditions are all present right now.”

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TANG, MATYASA Nowcasting Model for Tropical Cyclone Precipitation Regions Based on the TREC Motion Vector Retrieval with a Semi-Lagrangian Scheme for Doppler Weather Radar

Jingyin Tang and Corene Matyas

Article first published online: 21 May 2018 Atmosphere

DOI: 10.3390/atmos9050200

ABSTRACT: Accurate observational data and reliable prediction models are both essential to improve the quality of precipitation forecasts. The spiraling trajectories of air parcels within a tropical cyclone (TC) coupled with the large sizes of these systems brings special challenges in making accurate short-term forecasts, or nowcasts. Doppler weather radars are ideal instruments to observe TCs when they move over land, and traditional nowcasts incorporate radar data. However, data from dozens of radars must be mosaicked together to observe the entire system. Traditional single-radar-based reflectivity tracking methods commonly employed in nowcasting are not suitable for TCs as they are not able to capture the circular motion of these systems. Thus, this paper focuses on improving short-term predictability of TC precipitation with Doppler weather radar observations based on: a multi-scale motion vector retrieval algorithm, an optimization technique and a semi-Lagrangian advection scheme. Motion fields of precipitation regions are obtained by a multi-level motion vector retrieval algorithm, then corrected and smoothed by the optimization technique using mass and smooth constraints. Predicted precipitation regions are then extrapolated using the semi-Lagrangian advection scheme. A case study of Hurricane Isabel (2003) shows that the combination of these methods may increase reliable rainfall prediction to about 5 h as the TC moves over land.

Read the full publication at Atmosphere