Journal Article
Hydrology and Earth System Sciences, vol. 24, iss. 5, pp. 2303-2322, 2020
Authors
Kurt C. Solander, Brent D. Newman, Alessandro Carioca de Araujo, Holly R. Barnard, Z. Carter Berry, Damien Bonal, Mario Bretfeld, Benoit Burban, Luiz Antonio Candido, Rolando Célleri, Jeffery Q. Chambers, Bradley O. Christoffersen, Matteo Detto, Wouter A. Dorigo, Brent E. Ewers, Savio José Filgueiras Ferreira, Alexander Knohl, L. Ruby Leung, Nate G. McDowell, Gretchen R. Miller, Maria Terezinha Ferreira Monteiro, Georgianne W. Moore, Robinson Negrón-Juárez, Scott R. Saleska, Christian Stiegler, Javier Tomasella, Chonggang Xu
Abstract
Abstract. The 2015–2016 El Niño event ranks as one of the most severe on record in
terms of the magnitude and extent of sea surface temperature (SST) anomalies
generated in the tropical Pacific Ocean. Corresponding global impacts on the
climate were expected to rival, or even surpass, those of the 1997–1998 severe
El Niño event, which had SST anomalies that were similar in size.
However, the 2015–2016 event failed to meet expectations for hydrologic change
in many areas, including those expected to receive well above normal
precipitation. To better understand how climate anomalies during an El
Niño event impact soil moisture, we investigate changes in soil moisture
in the humid tropics (between ±25∘) during the three most
recent super El Niño events of 1982–1983, 1997–1998 and 2015–2016, using data
from the Global Land Data Assimilation System (GLDAS). First, we use in situ
soil moisture observations obtained from 16 sites across five continents to
validate and bias-correct estimates from GLDAS (r2=0.54). Next, we
apply a k-means cluster analysis to the soil moisture estimates during the
El Niño mature phase, resulting in four groups of clustered data. The
strongest and most consistent decreases in soil moisture occur in the Amazon
basin and maritime southeastern Asia, while the most consistent increases occur
over eastern Africa. In addition, we compare changes in soil moisture to both
precipitation and evapotranspiration, which showed a lack of agreement in
the direction of change between these variables and soil moisture most
prominently in the southern Amazon basin, the Sahel and mainland southeastern Asia.
Our results can be used to improve estimates of spatiotemporal differences
in El Niño impacts on soil moisture in tropical hydrology and ecosystem
models at multiple scales.
