Surface‐Atmosphere Coupling Scale, the Fate of Water, and Ecophysiological Function in a Brazilian Forest. (5th August 2019)

• Record Type: Journal Article
• Authors: Baker, Ian T.; Denning, A.Scott; Dazlich, Don A.; Harper, Anna B.; Branson, Mark D.; Randall, David A.; Phillips, Morgan C.; Haynes, Katherine D.; Gallup, Sarah M.
• Is Part Of: Journal of advances in modeling earth systems. Volume 11:Number 8(2019)
• Page Start: 2523
• Page End: 2546
• Publication Date: 2019-08-05
• Subjects: land‐atmosphere interaction -- multiscale modeling -- carbon cycle -- tropical ecophysiology; Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1029/2019MS001650
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: Tropical South America plays a central role in global climate. Bowen ratio teleconnects to circulation and precipitation processes far afield, and the global CO2 growth rate is strongly influenced by carbon cycle processes in South America. However, quantification of basin‐wide seasonality of flux partitioning between latent and sensible heat, the response to anomalies around climatic norms, and understanding of the processes and mechanisms that control the carbon cycle remains elusive. Here, we investigate simulated surface‐atmosphere interaction at a single site in Brazil, using models with different representations of precipitation and cloud processes, as well as differences in scale of coupling between the surface and atmosphere. We find that the model with parameterized clouds/precipitation has a tendency toward unrealistic perpetual light precipitation, while models with explicit treatment of clouds produce more intense and less frequent rain. Models that couple the surface to the atmosphere on the scale of kilometers, as opposed to tens or hundreds of kilometers, produce even more realistic distributions of rainfall. Rainfall intensity has direct consequences for the "fate of water, " or the pathway that a hydrometeor follows once it interacts with the surface. We find that the model with explicit treatment of cloud processes, coupled to the surface at small scales, is the most realistic when compared to observations. These results have implications for simulations of global climate, as the use of models with explicit (as opposed to parameterized) cloud representations becomes more widespread. Key Points: Ecophysiological function during seasonal drought is dependent upon storage and availability of rainfall that falls during the wet season The scale of coupling between land and atmosphere strongly influences this "fate of water" in simulations Simulations tend toward "water limitation" or "light limitation" depending on this scale of coupling