Simulation of rainfall anomalies leading to the 2005 drought in Amazonia using the CLARIS LPB regional climate models

Author(s):Show less -

Marengo, J. ^[1] ; Chou, S. ^[2] ; Mourao, C. ^[1] ; Solman, S. ^{[3, 4, 5]} ; Sanchez, E. ^[6] ; Samuelsson, P. ^[7] ; da Rocha, R. P. ^[8] ; Li, L. ^[9] ; Pessacg, N. ^[10] ; Remedio, A. R. C. ^[11] ; Carril, A. F. ^{[3, 4, 5]} ; Cavalcanti, I. F. ^[2] ; Jacob, D. ^{[11, 12]}

Affiliation:Show less -

^[1] Inst Nacl Pesquisas Espaciais, Ctr Ciencia Sistema Terrestre, BR-12630000 Sao Paulo - Brazil

^[2] Inst Nacl Pesquisas Espaciais, Ctr Previsao Tempo & Estudos Climat, BR-12630000 Sao Paulo - Brazil

^[3] CONICET UBA, Ctr Invest Mar & Atmosfera, Buenos Aires, DF - Argentina

^[4] Univ Buenos Aires, FCEN, Dept Ciencias Atmosfera & Oceanos, Buenos Aires, DF - Argentina

^[5] UMI IFAECI CNRS, Buenos Aires, DF - Argentina

^[6] Univ Castilla La Mancha, Fac Ciencias Ambient & Bioquim, Toledo - Spain

^[7] Swedish Meteorol & Hydrol Inst, Rossby Ctr, S-60176 Norrkoping - Sweden

^[8] Univ Sao Paulo, Dept Ciencias Atmosfer, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo - Brazil

^[9] UPMC, CNRS, IPSL, Meteorol Dynam Lab, Paris - France

^[10] Ctr Nacl Patagon CENPAT CONICET, Puerto Madryn, Chubut - Argentina

^[11] Max Planck Inst Meteorol, D-20146 Hamburg - Germany

^[12] Climate Serv Ctr, Hamburg - Germany

• Document type: Journal article
• Source: Climate Dynamics; v. 41, n. 11-12, p. 2937-2955, DEC 2013.
• Web of Science Citations: 3

Abstract

The meteorological characteristics of the drought of 2005 in Amazonia, one of the most severe in the last 100 years were assessed using a suite of seven regional models obtained from the CLARIS LPB project. The models were forced with the ERA-Interim reanalyses as boundary conditions. We used a combination of rainfall and temperature observations and the low-level circulation and evaporation fields from the reanalyses to determine the climatic and meteorological characteristics of this particular drought. The models reproduce in some degree the observed annual cycle of precipitation and the geographical distribution of negative rainfall anomalies during the summer months of 2005. With respect to the evolution of rainfall during 2004-2006, some of the models were able to simulate the negative rainfall departures during early summer of 2005 (December 2004 to February 2005). The interannual variability of rainfall anomalies for both austral summer and fall over northern and southern Amazonia show a large spread among models, with some of them capable of reproducing the 2005 observed negative rainfall departures (four out of seven models in southern Amazonia during DJF). In comparison, all models simulated the observed southern Amazonia negative rainfall and positive air temperature anomalies during the El Nino-related drought in 1998. The spatial structure of the simulated rainfall and temperature anomalies in DJF and MAM 2005 shows biases that are different among models. While some models simulated the observed negative rainfall anomalies over parts of western and southern Amazonia during DJF, others simulated positive rainfall departures over central Amazonia. The simulated circulation patterns indicate a weaker northeasterly flow from the tropical North Atlantic into Amazonia, and reduced flows from southern Amazonia into the La Plata basin in DJF, which is consistent with observations. In general, we can say that in some degree the regional models are able to capture the response to the forcing from the tropical Atlantic during the drought of 2005 in Amazonia. Moreover, extreme climatic conditions in response to anomalous low-level circulation features are also well captured, since the boundary conditions come from reanalysis and the models are largely constrained by the information provided at the boundaries. The analysis of the 2005 drought suggests that when the forcing leading to extreme anomalous conditions is associated with both local and non-local mechanisms (soil moisture feedbacks and remote SST anomalies, respectively) the models are not fully capable of representing these feedbacks and hence, the associated anomalies. The reason may be a deficient reproduction of the land-atmosphere interactions. (AU)

• FAPESP's process: 08/58161-1 - Assessment of impacts and vulnerability to climate change in Brazil and strategies for adaptation option
• Grantee: Jose Antonio Marengo Orsini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants