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system need to be added back into the system in an “averaged” sense via parameterizations of the subgrid-scale behavior. An important subgrid-scale phenomenon that needs parameterizing in this way is moist cumulus convection ( Arakawa 2004 ). This phenomenon plays a significant role in the vertical fluxes of entropy, air mass, moisture and air momentum in the atmosphere, each of which can have large magnitudes. This is particularly the case in the tropical regions of Earth’s atmosphere where these
system need to be added back into the system in an “averaged” sense via parameterizations of the subgrid-scale behavior. An important subgrid-scale phenomenon that needs parameterizing in this way is moist cumulus convection ( Arakawa 2004 ). This phenomenon plays a significant role in the vertical fluxes of entropy, air mass, moisture and air momentum in the atmosphere, each of which can have large magnitudes. This is particularly the case in the tropical regions of Earth’s atmosphere where these
1. Introduction Modern climate science inferred from global climate models (GCMs), as well as observations, points toward the important influence by cumulus convection on the vertical structure of the atmosphere. Through vertical distribution of heat, moisture, and momentum, cumulus convection determines precipitation and clouds, and largely affects the global energy balance through interaction with the solar and longwave radiation. State-of the-art climate and numerical weather prediction (NWP
1. Introduction Modern climate science inferred from global climate models (GCMs), as well as observations, points toward the important influence by cumulus convection on the vertical structure of the atmosphere. Through vertical distribution of heat, moisture, and momentum, cumulus convection determines precipitation and clouds, and largely affects the global energy balance through interaction with the solar and longwave radiation. State-of the-art climate and numerical weather prediction (NWP
1. Introduction Equilibrium convection is generally interpreted as indicating that the convection is in equilibrium with the forcing due to the mean advection and processes other than convection. In other words, the convection can react on time scales short enough for the residual tendency between the forcing and the convective stabilization to be small as measured by some function such as the cloud work function or the convective available potential energy (CAPE) ( Arakawa and Schubert 1974
1. Introduction Equilibrium convection is generally interpreted as indicating that the convection is in equilibrium with the forcing due to the mean advection and processes other than convection. In other words, the convection can react on time scales short enough for the residual tendency between the forcing and the convective stabilization to be small as measured by some function such as the cloud work function or the convective available potential energy (CAPE) ( Arakawa and Schubert 1974
Using satellite observations and large-eddy simulations of the development of deep moist convection over the tropics, Hohenegger and Stevens (2013) argued that the moistening of the atmosphere by congestus clouds is too slow to explain the observed fast transition times, from congestus to cumulonimbus. Schultz (2013) wondered whether this result remains valid for the midlatitudes. Although a full analysis as performed in Hohenegger and Stevens (2013) has not been conducted for the
Using satellite observations and large-eddy simulations of the development of deep moist convection over the tropics, Hohenegger and Stevens (2013) argued that the moistening of the atmosphere by congestus clouds is too slow to explain the observed fast transition times, from congestus to cumulonimbus. Schultz (2013) wondered whether this result remains valid for the midlatitudes. Although a full analysis as performed in Hohenegger and Stevens (2013) has not been conducted for the
1. Introduction One of the major challenges during the summer months is predicting the initiation of deep, moist convection ( Olsen et al. 1995 ; Fritsch and Carbone 2004 ). Forecasters often have difficulty assessing, under weak synoptically forced conditions, the potential of rising parcels of air to reach the level of free convection (LFC) and then maintaining positive buoyancy as they pass this level. Improvements in these short-term forecasts, however, resulted when organized lines of
1. Introduction One of the major challenges during the summer months is predicting the initiation of deep, moist convection ( Olsen et al. 1995 ; Fritsch and Carbone 2004 ). Forecasters often have difficulty assessing, under weak synoptically forced conditions, the potential of rising parcels of air to reach the level of free convection (LFC) and then maintaining positive buoyancy as they pass this level. Improvements in these short-term forecasts, however, resulted when organized lines of
the effect of convection on the large-scale circulation is to reduce the effective static stability of the atmosphere. Building on this approach, Frierson et al. (2004 , hereafter FMP) developed an idealized framework to study the feedback between water vapor and large-scale circulation that allows for interactions between precipitating and nonprecipitating regions. The model by FMP has been previously used to study the propagation of precipitating regions ( Stechmann and Majda 2006
the effect of convection on the large-scale circulation is to reduce the effective static stability of the atmosphere. Building on this approach, Frierson et al. (2004 , hereafter FMP) developed an idealized framework to study the feedback between water vapor and large-scale circulation that allows for interactions between precipitating and nonprecipitating regions. The model by FMP has been previously used to study the propagation of precipitating regions ( Stechmann and Majda 2006
. 2006 ). The ASM is divided into three distinct stages based on its climatological onset dates in different monsoon regions. In mid-May, the first transition of the ASM manifests rainfall over the Bay of Bengal and the South China Sea. Subsequently, in mid-June, the Indian summer monsoon begins and the East Asian rainy season arrives with mei-yu in China and baiu in Japan (mei-yu–baiu). Finally, after mid-July, convection over the western Pacific abruptly expands northeastward, forming a subtropical
. 2006 ). The ASM is divided into three distinct stages based on its climatological onset dates in different monsoon regions. In mid-May, the first transition of the ASM manifests rainfall over the Bay of Bengal and the South China Sea. Subsequently, in mid-June, the Indian summer monsoon begins and the East Asian rainy season arrives with mei-yu in China and baiu in Japan (mei-yu–baiu). Finally, after mid-July, convection over the western Pacific abruptly expands northeastward, forming a subtropical
1. Introduction In the tropics, deep convection constitutes the primary mechanism through which water vapor and energy are transported vertically in the troposphere. It is also responsible for a large part of the cloudiness and precipitation. Because deep convective regions are moister and cloudier than dry, subsiding areas, the fractional area of the tropics covered by deep convection is critical for the mean tropical climate and its sensitivity ( Pierrehumbert 1995 ; Larson et al. 1999 ). At
1. Introduction In the tropics, deep convection constitutes the primary mechanism through which water vapor and energy are transported vertically in the troposphere. It is also responsible for a large part of the cloudiness and precipitation. Because deep convective regions are moister and cloudier than dry, subsiding areas, the fractional area of the tropics covered by deep convection is critical for the mean tropical climate and its sensitivity ( Pierrehumbert 1995 ; Larson et al. 1999 ). At
first defined for convection by Stull (1984) [see also the review by Stull (1993) ]. As originally defined, the element b ij is proportional to the mass of air transported from z j at t = 0 to z i at t = Δ t (per infinitesimal intervals around z i and z j ). As such, is a function of the time interval Δ t . In a numerical simulation, b ij is easily diagnosed using a “set-and-go” method with tracers: initialize a horizontally uniform tracer q j at t = 0 in the layer
first defined for convection by Stull (1984) [see also the review by Stull (1993) ]. As originally defined, the element b ij is proportional to the mass of air transported from z j at t = 0 to z i at t = Δ t (per infinitesimal intervals around z i and z j ). As such, is a function of the time interval Δ t . In a numerical simulation, b ij is easily diagnosed using a “set-and-go” method with tracers: initialize a horizontally uniform tracer q j at t = 0 in the layer
1. Introduction Aggregated convection can often be observed in the tropics (e.g., Houze and Betts 1981 ; Tobin et al. 2012 ; Stein et al. 2017 ). Studies show that along with the aggregation of convection, large-scale temperature and water vapor can be altered (e.g., Bretherton et al. 2005 ; Muller and Held 2012 ). Understanding the organization of convection may deepen our understanding of tropical weather and climate. Intuitively, the aggregation tendency of convection could be
1. Introduction Aggregated convection can often be observed in the tropics (e.g., Houze and Betts 1981 ; Tobin et al. 2012 ; Stein et al. 2017 ). Studies show that along with the aggregation of convection, large-scale temperature and water vapor can be altered (e.g., Bretherton et al. 2005 ; Muller and Held 2012 ). Understanding the organization of convection may deepen our understanding of tropical weather and climate. Intuitively, the aggregation tendency of convection could be
