Presented on March 8, 2023, by

Prof. Yali Luo
Nanjing University of Information Science and Technology
Chinese Academy of Meteorological Sciences
The State Key Laboratory of Severe Weather
Beijing, China

Abstract:

Extreme precipitation is an issue of worldwide concern, but its microphysics remain elusive.
Using multisource data including 5-yr dual-polarization radar observations, convective and
microphysical characteristics of extreme precipitation features (EPFs) over a densely
populated monsoon coastal region in South China are investigated including the dependence
on rainfall extremity and subseasonal variations.

The EPFs are sorted into three groups according to the extreme rainfall intensity: 84 – 126
mm hr -1 (ER1), 126 – 186 mm hr -1 (ER2), ≥186 mm hr -1 (ER3). The more extreme rainfall
shows a notable increase and decrease in the fractions of “intense” convection (7.6%, 20.6%,
31.6%) and “weak” convection (41.3%, 22.9%, 18.9%), respectively, while that of the
“moderate” convection remain about 50%. The higher rainfall extremity is accompanied by
statistically significant increases in ice and liquid water contents and a slight decrease in the
fraction of coalescence in liquid-phase processes. While the raindrop size distributions
(RSDs) of ER1 to ER3 similarly feature a mean size larger than “maritime-like” droplets and
a concentration much higher than “continental-like” raindrops, the mean size and
concentration of raindrops tend to increase with the increasing rainfall extremity.

During the pre-monsoon period, precipitation systems are the largest in area but their EPFs
are the least frequent and have the lowest raindrop concentration, likely due to the colder,
drier environment with large vertical wind shear (VWS). Onset of the summer monsoon
increases the frequency and convective intensity of EPFs, leading to an increase in raindrop
size, consistent with the substantial increases of CAPE and moisture during the active-
monsoon period. EPFs share similar convective intensity and RSD between the post-monsoon and
active-monsoon periods, although the post-monsoon EPFs are slightly less frequent and have
a smaller horizontal scale related to the reduced 0–6-km VWS. EPFs associated with tropical
cyclones have the weakest convective intensity but the most active warm-rain processes with
the RSD being closer to the maritime regime.

Bio:

Yali Luo received the M.S. degree from the Chinese Academy of Meteorological
Sciences (CAMS), Beijing, China, in 1996, and the Ph.D. degree from The University of
Utah, Salt Lake City, UT, USA, in 2003.

After spending 3.5 years as a Research Scientist at the NASA Langley Research Center,
Hampton, VA, USA, she took a scientist position at the State Key Laboratory of Severe
Weather, CAMS, in July 2007. She was a Chief Scientist with CAMS from September
2019 to December 2022, where she was also the Chief Scientist of the Southern China
Monsoon Rainfall Experiment (SCMREX; 2013-2021) that was a Research and
Development Project (RDP) of the World Weather Organization’s World Weather
Research Programme. She took a professor position at Nanjing University of Information
Science and Technology in early 2023.

She works on the understanding of physical mechanisms governing the evolution and
long-term changes of weather/climate extremes especially heavy precipitation, using
integrated observational datasets combined with numerical modeling. She has about 100
refereed publications in journals, such as the Bulletin of the American Meteorological
Society and the Science Bulletin. She is one of the lead authors of the IPCC’s Special
Report on Extremes (SREX). Her research interests also include evaluation and
improvement of physics parameterization schemes in atmospheric models, i.e., cloud-
precipitation microphysics and convection schemes.