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, approximately independent of layer altitude. Such sensitivity implies that the distribution of humidity can have a significant role in the response of the Tropics in a climate-change scenario. Since specific humidity is conserved following an air mass in the absence of phase changes or mixing, its humidity is determined at the instant when condensation last occurred (assuming weak mixing and that the reevaporation of condensate is not important). The mixing ratio set by the condensation event depends on
, approximately independent of layer altitude. Such sensitivity implies that the distribution of humidity can have a significant role in the response of the Tropics in a climate-change scenario. Since specific humidity is conserved following an air mass in the absence of phase changes or mixing, its humidity is determined at the instant when condensation last occurred (assuming weak mixing and that the reevaporation of condensate is not important). The mixing ratio set by the condensation event depends on
so far in the global tropics. The purpose of this study is to construct a reference of the climatological diurnal precipitation in the global tropics using nine years of Tropical Rainfall Measuring Mission (TRMM) data and empirical orthogonal function (EOF) analysis. This work will not only provide a metric for evaluating global numerical models’ performance but also broaden our knowledge and shed some light on the mechanism at work. The TRMM data provide us this opportunity to study the
so far in the global tropics. The purpose of this study is to construct a reference of the climatological diurnal precipitation in the global tropics using nine years of Tropical Rainfall Measuring Mission (TRMM) data and empirical orthogonal function (EOF) analysis. This work will not only provide a metric for evaluating global numerical models’ performance but also broaden our knowledge and shed some light on the mechanism at work. The TRMM data provide us this opportunity to study the
changes in net tropospheric radiative cooling and latent heating ( Lambert and Webb 2008 ). However, the level of agreement between GCMs on regional precipitation changes is low throughout large areas of the tropics, with even the sign of change uncertain for many regions ( Meehl et al. 2007 ; Rowell 2012 ). Therefore, the mechanisms that lie behind the spatial patterns of the tropical rainfall response to climate change are of great interest. The aim of this study is to investigate these mechanisms
changes in net tropospheric radiative cooling and latent heating ( Lambert and Webb 2008 ). However, the level of agreement between GCMs on regional precipitation changes is low throughout large areas of the tropics, with even the sign of change uncertain for many regions ( Meehl et al. 2007 ; Rowell 2012 ). Therefore, the mechanisms that lie behind the spatial patterns of the tropical rainfall response to climate change are of great interest. The aim of this study is to investigate these mechanisms
region ( Minobe and Takebayashi 2015 ; Virts et al. 2015 ). These western boundary currents transport warm water from the tropics poleward, resulting in sea surface temperatures (SSTs) warmer than 26°C, the threshold of deep convection over the ocean under the current climate ( Graham and Barnett 1987 ; Waliser et al. 1993 ). The warm SST allows tropical-like atmospheric convection associated with the air–sea interaction with these currents ( Minobe et al. 2008 ; Minobe et al. 2010 ; Sasaki et al
region ( Minobe and Takebayashi 2015 ; Virts et al. 2015 ). These western boundary currents transport warm water from the tropics poleward, resulting in sea surface temperatures (SSTs) warmer than 26°C, the threshold of deep convection over the ocean under the current climate ( Graham and Barnett 1987 ; Waliser et al. 1993 ). The warm SST allows tropical-like atmospheric convection associated with the air–sea interaction with these currents ( Minobe et al. 2008 ; Minobe et al. 2010 ; Sasaki et al
atmospheric model simulations is also analyzed to investigate mechanisms of the teleconnections. We then extend the analysis back to the nineteenth century by using a network of coral and other proxy records from the tropics to test if the knowledge obtained from the analyses of ice core and instrumental data holds true for the past two centuries. The paper is organized as follows. Section 2 describes the ice core and various observational and tropical proxy data used in this study. Section 3 analyzes
atmospheric model simulations is also analyzed to investigate mechanisms of the teleconnections. We then extend the analysis back to the nineteenth century by using a network of coral and other proxy records from the tropics to test if the knowledge obtained from the analyses of ice core and instrumental data holds true for the past two centuries. The paper is organized as follows. Section 2 describes the ice core and various observational and tropical proxy data used in this study. Section 3 analyzes
Sanjay 2003 ). It is possible to use these weights and construct a single forecast model that uses a weighted average (based on these weights) for a unified model. Such a unified model was shown to carry a skill higher than those of the member models and their ensemble mean but lower than a multimodel superensemble. These results are shown in Figs. 1 and 2 for days 1 and 2 of rainfall forecasts over the global tropics, North America, and the Asian monsoon domain. In a related study, Chakraborty
Sanjay 2003 ). It is possible to use these weights and construct a single forecast model that uses a weighted average (based on these weights) for a unified model. Such a unified model was shown to carry a skill higher than those of the member models and their ensemble mean but lower than a multimodel superensemble. These results are shown in Figs. 1 and 2 for days 1 and 2 of rainfall forecasts over the global tropics, North America, and the Asian monsoon domain. In a related study, Chakraborty
1. Introduction Coupled ocean and atmosphere variations in the tropics involve variations that can generally (though oversimply) be classified as “zonal modes” [e.g. the El Niño–Southern Oscillation (ENSO) phenomenon, or the so-called Atlantic Niño] or “meridional modes” ( Servain et al. 1999 ; Chiang and Vimont 2004 ). A major difference between the two classifications is the physical mechanism that acts to destabilize the mode and hence allows the mode to emerge as a dominant pattern of
1. Introduction Coupled ocean and atmosphere variations in the tropics involve variations that can generally (though oversimply) be classified as “zonal modes” [e.g. the El Niño–Southern Oscillation (ENSO) phenomenon, or the so-called Atlantic Niño] or “meridional modes” ( Servain et al. 1999 ; Chiang and Vimont 2004 ). A major difference between the two classifications is the physical mechanism that acts to destabilize the mode and hence allows the mode to emerge as a dominant pattern of
1. Introduction Convective heating is extremely important for the maintenance of global-scale atmospheric circulation. The diurnal cycle of precipitation is a prominent mode in the tropical convective systems; thus, it has often been a target of intensive observations in the tropics ( Houze et al. 1981 ; Skinner and Tapper 1994 ; Mapes et al. 2003a , b ; Zuidema 2003 ; Mori et al. 2004 ). The spaceborne observation established by the Tropical Rainfall Measuring Mission (TRMM) satellite has
1. Introduction Convective heating is extremely important for the maintenance of global-scale atmospheric circulation. The diurnal cycle of precipitation is a prominent mode in the tropical convective systems; thus, it has often been a target of intensive observations in the tropics ( Houze et al. 1981 ; Skinner and Tapper 1994 ; Mapes et al. 2003a , b ; Zuidema 2003 ; Mori et al. 2004 ). The spaceborne observation established by the Tropical Rainfall Measuring Mission (TRMM) satellite has
1. Introduction The convective parameterizations of climate models are typically adjusted to give reasonable climatological distributions of temperature, water vapor, convective mass transport, and rainfall in the tropics. However, these climatological distributions arise from the cumulative impact of individual moist convective events that occur on much shorter time scales. Realistic convective parameterizations should be able to simulate the short-time-scale interactions between moist
1. Introduction The convective parameterizations of climate models are typically adjusted to give reasonable climatological distributions of temperature, water vapor, convective mass transport, and rainfall in the tropics. However, these climatological distributions arise from the cumulative impact of individual moist convective events that occur on much shorter time scales. Realistic convective parameterizations should be able to simulate the short-time-scale interactions between moist
, we show how some of the changes in the observing system appear to have adversely affected the ECMWF reanalyses of the temperature and moisture fields in the Tropics. Those influences are seen in other fields as well, thereby potentially limiting the usefulness of the reanalyses in addressing climate variability. Comprehensive evaluation of the moisture budget from NCEP–NCAR reanalysis was given by Trenberth and Guillemot (1998) who concluded that there is a negative bias in tropical
, we show how some of the changes in the observing system appear to have adversely affected the ECMWF reanalyses of the temperature and moisture fields in the Tropics. Those influences are seen in other fields as well, thereby potentially limiting the usefulness of the reanalyses in addressing climate variability. Comprehensive evaluation of the moisture budget from NCEP–NCAR reanalysis was given by Trenberth and Guillemot (1998) who concluded that there is a negative bias in tropical
