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M. Issa Lélé, Lance M. Leslie, and Peter J. Lamb

most limiting parameters for sustaining life, agriculture, and economic development in the sub-Saharan West African countries. Therefore, the role played by the atmospheric moisture transfer and its phase transitions through evaporation, latent heat release, and associated energy transports and exchanges are of central importance for the WAM dynamics and variability. This is because hydrological processes play an important role in determining the scales of the major circulation patterns (e

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Luis Gimeno, Raquel Nieto, Ricardo M. Trigo, Sergio M. Vicente-Serrano, and Juan Ignacio López-Moreno

1. Introduction About 90% of the water in the atmosphere emanates from the oceans, lakes, and other open water bodies ( Quante and Matthias 2006 ). Through atmospheric transport and associated transfer processes, some of the water that evaporates over the oceans reaches the land and may precipitate. It is crucial to understand the processes that govern moisture transport in the troposphere ( Trenberth et al. 2003 ) and how transport might affect the hydrological cycle ( Alley et al. 2007

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Cathy Hohenegger, Peter Brockhaus, Christopher S. Bretherton, and Christoph Schär

1. Introduction Interactions between land and the atmosphere play an important role in our climate system and have been the focus of modeling studies on a wide range of time and spatial scales (e.g., Pielke 2001 ; Betts 2004 ; Koster et al. 2004 ; Schär et al. 1999 ). On seasonal time scales, soil moisture anomalies may maintain/amplify subsequent extreme events such as droughts, floods, or summer heat waves (e.g., Beljaars et al. 1996 ; Trenberth and Guillemot 1996 ; Fischer et al. 2007

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Benjamin A. Schenkel and Robert E. Hart

their tropical environment for weeks following TC passage for the region within approximately 250 km of the TC track ( Hart et al. 2007 , 2008 ; Schenkel and Hart 2011 ) and potentially on spatial scales extending across entire ocean basins ( Sobel and Camargo 2005 ). However, these studies did not objectively define the mean spatiotemporal scales of the environmental moisture anomalies due to a single TC or how these moisture anomalies are generated. Accordingly, the present study objectively

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Sonia I. Seneviratne, Randal D. Koster, Zhichang Guo, Paul A. Dirmeyer, Eva Kowalczyk, David Lawrence, Ping Liu, David Mocko, Cheng-Hsuan Lu, Keith W. Oleson, and Diana Verseghy

1. Introduction Soil moisture memory, in essence the fact that the soil can “remember” a wet or dry anomaly long after the conditions responsible for the anomaly are forgotten by the atmosphere, is a key aspect of land–atmosphere interactions and has major implications for seasonal forecasting. Indeed, due to its inherent memory, soil moisture is one of the major “slow” drivers of the climate system and possibly the chief source of forecast skill for summer precipitation over land in the

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Qing Liu, Rolf H. Reichle, Rajat Bindlish, Michael H. Cosh, Wade T. Crow, Richard de Jeu, Gabrielle J. M. De Lannoy, George J. Huffman, and Thomas J. Jackson

1. Introduction Soil moisture is an important component of the land surface water budget. Large-scale soil moisture data are useful in many research fields such as hydrology, agriculture, and ecology ( Robock et al. 1998 ; Koster et al. 2008 ; Entekhabi et al. 2010a ). Soil moisture is also a critical variable that needs to be carefully initialized for weather and climate prediction ( Beljaars et al. 1996 ; Drusch 2007 ; Mahfouf 2010 ). In situ measurements of soil moisture, however, are

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Laurel L. De Haan and Masao Kanamitsu

1. Introduction It has been well understood for many years that the response of general circulation models to tropical sea surface temperatures (SSTs) is of primary importance to climate prediction. However, it has become apparent more recently that soil moisture has an important secondary role. As a result, there has been an increased interest in understanding the impact of soil moisture on near-surface temperature and precipitation in general circulation models (GCMs). The influence of soil

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Sun Wong, Catherine M. Naud, Brian H. Kahn, Longtao Wu, and Eric J. Fetzer

1. Introduction A key question related to climate sensitivity is how clouds and precipitation respond to changes in the large-scale circulation ( Bony et al. 2015 ). A more direct and fundamental question is how clouds and precipitation respond to changes in moisture flux convergence induced by changes in the large-scale circulation. In this work, we investigate moisture balance in extratropical cyclones (ETCs) to quantify coupling of precipitation and cloud processes to the large

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Clemens Schwingshackl, Martin Hirschi, and Sonia I. Seneviratne

role of soil moisture, since it affects various exchange processes at the surface. Seneviratne et al. (2010) provide an overview on the role of soil moisture for climate variability and land–atmosphere exchange. Based on both observational and modeling studies, various authors have shown that soil moisture has an impact on the evolution of near-surface air temperature ( Seneviratne et al. 2006 ; Koster et al. 2009b ; Jaeger and Seneviratne 2011 ; Seneviratne et al. 2013 ; Hirschi et al. 2014

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Randal D. Koster, Rolf H. Reichle, Siegfried D. Schubert, and Sarith P. Mahanama

scales characterizing the variabilities of soil moisture, evapotranspiration, and streamflow. As outlined in section 4 below, the overall spatial connectedness of hydrological variations can have important impacts on measurement strategies as well as on hydrological and climatic processes that influence society; it is more than a statistical curiosity. Available relatively recently to the hydrological community are global gridded datasets of satellite-derived moisture in the top several centimeters

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