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UID:20250809T204954EDT-7471Zguvij@132.216.98.100
DTSTAMP:20250810T004954Z
DESCRIPTION:Please join us as we welcome Dr. Allison Wing from the Lamont D
 oherty Earth Observatory at Columbia University for her seminar titled Org
 anization of tropical convection: Self-aggregation and spontaneous tropica
 l cyclogenesis. Refreshments will be served.\n\n\nAbstract\n\nTropical clo
 uds and relative humidity play a key role in both the planetary energy bal
 ance and the sensitivity of global climate to radiative forcing. Both clou
 ds and relative humidity are also strongly modulated by the organization o
 f tropical convection\, which results in a large fraction of tropical clou
 diness and rainfall. Here\, we investigate the organization of tropical co
 nvection in the context of self-aggregation\, a spontaneous transition in 
 idealized numerical  simulations from randomly distributed to organized co
 nvection despite homogeneous boundary conditions. Specifically\, the Syste
 m for Atmospheric Modeling is used to perform 3-d simulations of radiative
 -convective equilibrium in a non-rotating framework\, with interactive rad
 iation and surface fluxes and fixed sea surface temperatures. The results 
 of simulations employing a highly elongated 3-d channel domain\, in which 
 self-aggregation takes the form of multiple moist and dry bands\, are comp
 ared to that of a square domain\, in which self-aggregation takes the form
  of a single moist cluster. For both domain types\, and across a range of 
 temperatures\, we characterize the fundamental physical mechanisms that le
 ad to self-aggregation as well as its growth rate and spatial scale. In bo
 th geometries\, cloud-radiative feedbacks and surface flux feedbacks are f
 ound to be important in the initial instability\, but advection only contr
 ibutes to aggregation in the square geometry.\n\nSelf-aggregation has prim
 arily been studied in a non-rotating framework\, but it has been hypothesi
 zed to be important to tropical cyclogenesis. In numerical simulations of 
 tropical cyclones\, a broad vortex or moist bubble is often used to initia
 lize the circulation. Here\, we instead allow a circulation to develop spo
 ntaneously from a homogeneous environment in 3-d cloud-resolving simulatio
 ns of radiative-convective equilibrium (RCE) in a rotating framework\, and
  compare the resulting tropical cyclogenesis to non-rotating self-aggregat
 ion. We find that in the initial development of a broad circulation\, the 
 feedback processes leading to cyclogenesis are similar to the initial phas
 e of non-rotating aggregation. Sensitivity tests in which the degree of in
 teractive radiation is modified are also performed to determine the extent
  to which the radiative feedbacks that are essential to non-rotating self-
 aggregation are important for tropical cyclogenesis.\n
DTSTART:20160118T203000Z
DTEND:20160118T213000Z
LOCATION:Room 934\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue 
 Sherbrooke Ouest
SUMMARY:Seminar: Dr. Allison Wing
URL:/meteo/channels/event/seminar-dr-allison-wing-2571
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