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Coloquio // “Daytime convective development over land: the role of surface forcing” Dr. Wojciech Grabowski, Faculty of Physics,University of Warsaw

6 de septiembre / / 13:00 - 14:00

MARTES 06/09, a las 13hs:
**** Presencial: Aula 8 (ex Dcao, 2do piso, Pab 2) ****
(Con el orador presente)
“Daytime convective development over land: the role of surface forcing”
Dr. Wojciech Grabowski, Faculty of Physics,University of Warsaw
Diurnal cycle of solar radiation over tropical and midlatitude summertime continents forces strong evolution of atmospheric convection. As surface sensible and latent heat fluxes increase after sunrise, a dry convective boundary layer develops in the early morning hours. It proceeds with the formation of shallow convective clouds as the convective boundary layer deepens and may eventually lead to the transition from shallow to deep precipitating convection. Factors affecting shallow-to-deep convection transition have been studied in the past, but the early evolution of dry convection and how it affects development of shallow convection and eventual transition to deep convection attracted much less attention.
This presentation will discuss a set of large-eddy simulations that considers the impact of the surface flux Bowen ratio, the partitioning of the surface heat flux into sensible and latent components, on the development of dry and eventually moist convection. The key point is that the Bowen ratio affects the surface buoyancy flux and thus growth of dry convective boundary layer before the moist convection onset. This has a strong impact on the development and organization of shallow convection and eventual transition to deep convection. Details of the simulation results will be discussed.

Dr. Wojciech Grabowski is a Polish-American cloud physicist. He obtained his MSc and PhD
degrees in Poland (from the University of Warsaw’s Physics Department and Polish Academy of
Sciences, respectively) in the 1980ies. He moved to the National Center for Atmospheric
Research (NCAR) in 1987 after receiving a prestigious NCAR’s Advanced Study Program
Postdoctoral Fellowship. He has been at NCAR since then, currently as a Senior Scientist (since
2005) at the Mesoscale and Microscale Meteorology Laboratory. His main areas of interest
include computational fluid dynamics and numerical modeling in general, and more specifically
modeling of cloud dynamics and microphysics, interactions of clouds with radiation and surface
processes, and representation of these processes in numerical models of small-scale dynamics,
weather, and climate. He obtained habilitation [a post-PhD degree, equivalent of the Doctor of
Science (DSc)] from the Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland,
in 1999. In 2013 he received the title of Professor of Physical Sciences of the Republic of
Poland. He was a member of the Committee on Cloud Physics of the American Meteorological
Society between 1995 and 1998, and a member of the International Commission on Clouds and
Precipitation between 2000 and 2008. He is a Fellow of the Royal Meteorological Society and of
the American Meteorological Society. He is the Affiliate Professor of the Faculty of Physics,
University of Warsaw. Dr. Grabowski published over 160 papers in atmospheric science journals
and similar number of papers in conference proceedings. His papers attracted over 11,000
citations (H=57, He
served as a member of editorial boards for the Quarterly Journal of the Royal Meteorological
Society (2001-2008), Atmospheric Science Letters (2000-2011), Journal of the Atmospheric
Sciences (2006-2019), and the Journal of Advances in Modeling Earth Systems (JAMES, 2008-


6 de septiembre
13:00 - 14:00