At #AGU21, we present updates on understanding diurnal temperature variations on land and on deriving precipitation sensitivities from observations using “clear-sky” temperatures and maximum power

Corona has not yet gone away, but the AGU Fall Meeting nevertheless takes place, in a hybrid format. Annu Panwar will be physically there, giving an invited talk on her PhD thesis on diurnal temperature variations (see, e.g., her paper in HESS) and a poster, while Sarosh Alam Ghausi will be giving his poster on precipitation scaling virtually.

Annu will be presenting two abstracts and fortunately, her participation will be in person. We are excited about her first abstract being an invited talk in the session B15G: “Improving Understanding of Land-Atmosphere Interactions Through Integration of Surface Layer, Atmospheric Composition, and Atmospheric Boundary Layer Measurements II Poster”. This session focuses on integrating multiple observations to disentangle complex land-atmosphere feedback mechanisms.  She takes this opportunity to present her Ph.D. research that also integrates ground-based FLUXNET observations and ERA5 reanalysis to understand the main mechanisms shaping diurnal surface and air temperature variations (the manuscript is currently being reviewed in Journal of Climate). Her talk entitled “Imprints of Evaporation, Vegetation and Boundary Layer Dynamics on Temperature” will take place on Monday, 13 December 2021 at 08:37 – 08:47 CST in the Convention center room 231-232. This talk summarizes her previously published work (Panwar et al. 2019, Panwar et al. 2020) and further elaborates on the main physical mechanisms that shape surface and air temperature differently, as described in the new manuscript. The same day in the evening (16:00 – 18:00 CST) she will present her poster entitled, “Factors leading to air temperature variability in the event of deforestation” in session B15H: “Surface-Atmosphere Interactions: From Single Flux Measurements to Integrated Synthesis”. This poster will demonstrate some preliminary findings on her ongoing work that focuses on deforestation-induced changes in albedo, evaporation, and vegetation aerodynamic properties and their impact on diurnal variations of air temperature. Both of these presentations will also be available online for the registered attendees. See you in New Orleans!

Sarosh presents his poster “Cloud radiative cooling explains the global variability in precipitation – temperature scaling derived from observations” in the session A25H “Extreme precipitation in past, present and future climates” on Tuesday, 14 December 2021. His work focusses on estimating the sensitivity of precipitation extremes from observations at a global scale. He explains that the uncertainties and systematic zonal variabilities that are encountered in these sensitivity estimates arises due to radiative effect of clouds on surface temperatures. He uses our maximum power approach (e.g., Kleidon et al. 2014, Dhara et al. 2016) as an additional constraint on the convective exchange between surface and atmosphere to derive what we call “clear-sky” temperatures, that is, surface temperatures without the effect of clouds (the clear-sky radiative fluxes are a standard product included in the CERES dataset). He then shows that when the confounding effects of clouds is removed, the hydrologic sensitivities derived from observations become much clearer. His findings revealed that precipitation extremes will intensify in a warmer climate, consistent with the climate model projections. To learn more about his work, meet him virtually in session A25H between 16:00 to 18:00 CST).


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