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DTSTAMP:20260417T115552Z
DESCRIPTION:Atmospheric and Oceanic Sciences Departmental Seminar Series\n
 \npresents\n\nUse of In-situ Cloud Microphysical Observations for Quantify
 ing Ice Cloud Microphysical Properties and Processes\, and their Uncertain
 ties\n\na talk by\n\nGreg M. McFarquhar\n	Professor\, \n	Cooperative Institu
 te for Mesoscale Meteorological Studies and School of Meteorology\,\n	Unive
 rsity of Oklahoma\, Norman\, OK\n\nIce clouds currently reflect ~17 W m-2 
 of shortwave radiation and trap ~22 W m-2 of longwave radiation on global 
 average. However\, if the distribution of cloud heights and microphysical 
 properties changes in response to increases in greenhouse gases and aeroso
 ls\, associated changes in the radiative impact of clouds could feed back 
 on Earth’s climate. Representations of ice particle density\, scattering a
 nd sedimentation are needed for global and regional climate models that pr
 edict these effects. Parameterizations of other processes\, such as riming
 \, aggregation\, sedimentation and evaporation\, are also needed for numer
 ical weather models that predict the destructive impact and quantitative p
 recipitation forecasts for winter storms\, hurricanes\, mesoscale convecti
 ve systems and other events. Further\, algorithms retrieving cloud propert
 ies from ground- and satellite-based sensors require assumptions about ice
  crystal properties. To develop such parameterizations\, accurate observat
 ions of ice particle sizes\, shapes\, phases and concentrations are needed
 .\n\nTechniques measuring these ice crystal properties are reviewed. Sourc
 es of uncertainty\, related to statistical counting\, variability in cloud
  properties for similar environmental conditions\, and errors induced by t
 he processing of data and the instruments themselves are discussed using d
 ata collected over Alaska\, Australia\, and the continental United States.
  It is shown that although there are still uncertainties in in-situ observ
 ations of small ice crystals due to potential shattering of large particle
 s on probe tips and the limited resolution of state-of-the-art cloud parti
 cle imagers\, progress on characterizing small crystals has been made. The
  use of instrumental and statistical uncertainties in the development of s
 tochastic cloud parameterizations is then introduced. A specific applicati
 on to the representation of mass-dimensional (m-D) relationships m=aDb is 
 shown\, where (a\,b) are given as surfaces of equally realizable solutions
  rather than fixed values. The incorporation of such a stochastic paramete
 rization in the P3 scheme of the Weather Research and Forecasting (WRF) mo
 del for an ensemble simulation of a mid-latitude convective anvil changes 
 the cloud radiative effects in comparison to a deterministic scheme. Final
 ly\, new projects underway and planned to better characterize cloud microp
 hysical properties and processes are reviewed.\n\nMonday Jan 06/ 3:30 PM/ 
 Burnside Hall/ Room 934\n
DTSTART:20200106T203000Z
DTEND:20200106T220000Z
LOCATION:Room 934
SUMMARY:Use of In-situ Cloud Microphysical Observations for Quantifying Ice
  Cloud Microphysical Properties and Processes\, and their Uncertainties
URL:https://www.mcgill.ca/meteo/channels/event/use-situ-cloud-microphysical
 -observations-quantifying-ice-cloud-microphysical-properties-and-303426
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