TY - JOUR
T1 - Cloud and radiative balance changes in response to ENSO in observations and models
AU - Radley, Claire
AU - Fueglistaler, Stephan Andreas
AU - Donner, Leo
N1 - Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 2014/5
Y1 - 2014/5
N2 - The authors use observations and four GFDL AGCMs to analyze the relation between variations in spatial patterns and area-averaged quantities in the top-of-the-atmosphere radiative fluxes, cloud amount, and precipitation related to El Niño over the period 1979-2008. El Niño is associated with an increase in tropical average sea surface temperature of order +0.1K (with a maxima of +0.5 K), large local anomalies of +2K (maxima +6 K), and tropical tropospheric warming of +0.5K (maxima +1 K). The authors find that modelto-observation biases in the base state translate into corresponding biases in anomalies in response to El Niño. The pattern and amplitude of model biases in reflected shortwave (SW) and outgoing longwave radiation (OLR) follows expectations based on their biases in cloud amount: models with a positive cloud amount bias, compared to observations, have too strong local responses to El Niño in cloud amount, SW, OLR, and precipitation. Tropical averageOLRincreases in response to El Niño in observations and models [correlation coefficients (r) with Niño-3.4 index in the range 0.4-0.6]. Weaker correlations are found for SW (r: -0.6 to 0), cloud amount (r: -0.2 to +0.1), and precipitation (r: -0.2 to 0). Compositing El Niño events over the period 2001- 07 yields similar results. These results are consistent with El Niño periods being warmer due to a heat pulse from the ocean, and a weak response in clouds and their radiative effect. These weak responses occur despite a large rearrangement in the spatial structure of the tropical circulation, and despite substantial differences in the mean state of observations and models.
AB - The authors use observations and four GFDL AGCMs to analyze the relation between variations in spatial patterns and area-averaged quantities in the top-of-the-atmosphere radiative fluxes, cloud amount, and precipitation related to El Niño over the period 1979-2008. El Niño is associated with an increase in tropical average sea surface temperature of order +0.1K (with a maxima of +0.5 K), large local anomalies of +2K (maxima +6 K), and tropical tropospheric warming of +0.5K (maxima +1 K). The authors find that modelto-observation biases in the base state translate into corresponding biases in anomalies in response to El Niño. The pattern and amplitude of model biases in reflected shortwave (SW) and outgoing longwave radiation (OLR) follows expectations based on their biases in cloud amount: models with a positive cloud amount bias, compared to observations, have too strong local responses to El Niño in cloud amount, SW, OLR, and precipitation. Tropical averageOLRincreases in response to El Niño in observations and models [correlation coefficients (r) with Niño-3.4 index in the range 0.4-0.6]. Weaker correlations are found for SW (r: -0.6 to 0), cloud amount (r: -0.2 to +0.1), and precipitation (r: -0.2 to 0). Compositing El Niño events over the period 2001- 07 yields similar results. These results are consistent with El Niño periods being warmer due to a heat pulse from the ocean, and a weak response in clouds and their radiative effect. These weak responses occur despite a large rearrangement in the spatial structure of the tropical circulation, and despite substantial differences in the mean state of observations and models.
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U2 - 10.1175/JCLI-D-13-00338.1
DO - 10.1175/JCLI-D-13-00338.1
M3 - Article
AN - SCOPUS:84899115168
SN - 0894-8755
VL - 27
SP - 3100
EP - 3113
JO - Journal of Climate
JF - Journal of Climate
IS - 9
ER -