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SUMMARY:Aerosols and clouds in the UKCA across time and space -  Daniel Gr
 osvenor\, Institute for Climate and Atmospheric Science (ICAS)\, Universit
 y of Leeds\,
DTSTART:20240604T103000Z
DTEND:20240604T113000Z
UID:TALK216610@talks.cam.ac.uk
CONTACT:Vichawan (Print) Sakulsupich
DESCRIPTION:\nIn this talk I will present work that I have done on aerosol
 s and clouds in UKCA-based models: the UK Earth System climate model and t
 he regional high resolution UKCA model. The work spans a large range of ti
 me and spatial scales ranging from historical climate modelling of the 185
 0-2014 period to a case study of volcanic event at 4km resolution.\n\n \n\
 nIn the historical study we determined what caused the long-term trends in
  the upwelling short-wave (SW) top-of-the-atmosphere (TOA) fluxes over the
  North Atlantic region. The UKESM showed a positive trend between 1850 and
  1970 (increasing SW reflection) and a negative trend between 1970 and 201
 4. We found that the 1850–1970 positive trend is mainly driven by an inc
 rease in cloud droplet number concentration due to increases in aerosol\, 
 while the 1970–2014 trend was mainly driven by a decrease in cloud fract
 ion\, which we attributed mainly to cloud feedbacks caused by greenhouse g
 as-induced warming.\n\n \n\nIn the high resolution modelling work we use a
 n eruption of sulphur dioxide from the Kilauea volcano in Hawaii as a natu
 ral laboratory to evaluate aerosol-cloud interaction processes against sat
 ellite observations. The model produces an increase in aerosol optical dep
 th due to the volcano that is too large compared to observations\, but the
  increase in cloud droplet number concentration compares well. The cloud l
 iquid water path (a measure of cloud thickness) and cloud fraction respons
 es are in the opposite direction what is observed\, although with a large 
 observational uncertainty. This suggests some issues with the model\, but 
 also underscores the difficulty in observing aerosol-cloud interactions.\n
 \n \n\nI'm now working in the UKESM development team at the Met Office. Th
 erefore I will also look forwards towards the next iterations of the UKESM
  model with respect to aerosols and clouds\, where we hope to bring togeth
 er the things learnt from the research across various time and spatial sca
 les that has been performed by scientists across the UK.
LOCATION:Chemistry Dept\, Unilever Lecture Theatre and Zoom
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