scholarly journals Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming

2013 ◽  
Vol 26 (14) ◽  
pp. 5028-5043 ◽  
Author(s):  
Caroline Muller
Keyword(s):  
Water Vapor ◽  
Surface Water ◽  
Precipitation Extremes ◽  
Vertical Shear ◽  
Tropical Precipitation ◽  
Fractional Rate ◽  
Squall Lines ◽  
Rate Of Increase ◽  
Cloud Resolving Model ◽  
Organized Convection

Abstract In this study the response of tropical precipitation extremes to warming in organized convection is examined using a cloud-resolving model. Vertical shear is imposed to organize the convection into squall lines. Earlier studies show that in disorganized convection, the fractional increase of precipitation extremes is similar to that of surface water vapor, which is substantially smaller than the increase in column water vapor. It has been suggested that organized convection could lead to stronger amplifications. Regardless of the strength of the shear, amplifications of precipitation extremes in the cloud-resolving simulations are comparable to those of surface water vapor and are substantially less than increases in column water vapor. The results without shear and with critical shear, for which the squall lines are perpendicular to the shear, are surprisingly similar with a fractional rate of increase of precipitation extremes slightly smaller than that of surface water vapor. Interestingly, the dependence on shear is nonmonotonic, and stronger supercritical shear yields larger rates, close to or slightly larger than surface humidity. A scaling is used to evaluate the thermodynamic and dynamic contributions to precipitation extreme changes. To first order, they are dominated by the thermodynamic component, which has the same magnitude for all shears, close to the change in surface water vapor. The dynamic contribution plays a secondary role and tends to weaken extremes without shear and with critical shear, while it strengthens extremes with supercritical shear. These different dynamic contributions for different shears are due to different responses of convective mass fluxes in individual updrafts to warming.

scholarly journals Intensification of Precipitation Extremes with Warming in a Cloud-Resolving Model

2011 ◽  
Vol 24 (11) ◽  
pp. 2784-2800 ◽  
Author(s):  
Caroline J. Muller ◽  
Paul A. O’Gorman ◽  
Larissa E. Back
Keyword(s):  
Water Vapor ◽  
Climate Model ◽  
Atmospheric Temperature ◽  
Precipitation Extremes ◽  
Temperature Structure ◽  
Precipitation Efficiency ◽  
Fractional Rate ◽  
Cloud Resolving Model ◽  
Climate Model Simulations ◽  
Static Energy

Abstract A cloud-resolving model is used to investigate the effect of warming on high percentiles of precipitation (precipitation extremes) in the idealized setting of radiative-convective equilibrium. While this idealized setting does not allow for several factors that influence precipitation in the tropics, it does allow for an evaluation of the response of precipitation extremes to warming in simulations with resolved rather than parameterized convection. The methodology developed should also be applicable to less idealized simulations. Modeled precipitation extremes are found to increase in magnitude in response to an increase in sea surface temperature. A dry static energy budget is used to relate the changes in precipitation extremes to changes in atmospheric temperature, vertical velocity, and precipitation efficiency. To first order, the changes in precipitation extremes are captured by changes in the mean temperature structure of the atmosphere. Changes in vertical velocities play a secondary role and tend to weaken the strength of precipitation extremes, despite an intensification of updraft velocities in the upper troposphere. The influence of changes in condensate transports on precipitation extremes is quantified in terms of a precipitation efficiency; it does not change greatly with warming. Tropical precipitation extremes have previously been found to increase at a greater fractional rate than the amount of atmospheric water vapor in observations of present-day variability and in some climate model simulations with parameterized convection. But the fractional increases in precipitation extremes in the cloud-resolving simulations are comparable in magnitude to those in surface water vapor concentrations (owing to a partial cancellation between dynamical and thermodynamical changes), and are substantially less than the fractional increases in column water vapor.

scholarly journals Scaling of Precipitation Extremes over a Wide Range of Climates Simulated with an Idealized GCM

2009 ◽  
Vol 22 (21) ◽  
pp. 5676-5685 ◽  
Author(s):  
Paul A. O’Gorman ◽  
Tapio Schneider
Keyword(s):  
Precipitation Extremes ◽  
Lapse Rate ◽  
Fractional Rate ◽  
Rate Of Increase ◽  
Wide Range ◽  
Simple Scaling ◽  
Precipitation Increase ◽  
The Mean ◽  
The Difference ◽  
Global Mean

Abstract Extremes of precipitation are examined in a wide range of climates simulated with an idealized aquaplanet GCM. The high percentiles of daily precipitation increase as the climate warms. Their fractional rate of increase with global-mean surface temperature is generally similar to or greater than that of mean precipitation, but it is less than that of atmospheric (column) water vapor content. A simple scaling is introduced for precipitation extremes that accounts for their behavior by including the effects of changes in the moist-adiabatic lapse rate, the circulation strength, and the temperature when the extreme events occur. The effects of changes in the moist-adiabatic lapse rate and circulation strength on precipitation extremes are important globally, whereas the difference in the mean temperature and the temperature at which precipitation extremes occur is important only at middle to high latitudes.

Response of Tropical Precipitation to Global Warming

2011 ◽  
Vol 68 (1) ◽  
pp. 123-138 ◽  
Author(s):  
David M. Romps
Keyword(s):  
Global Warming ◽  
Water Vapor ◽  
High Resolution ◽  
General Circulation ◽  
Co2 Concentration ◽  
General Circulation Models ◽  
Tropical Convection ◽  
Precipitation Extremes ◽  
Tropical Precipitation ◽  
Effective Water

Abstract Using high-resolution cloud-resolving simulations with different CO2 concentrations, local precipitation fluxes are found to obey Clausius–Clapeyron (CC) scaling. Previous studies of the effect of CO2 concentration on precipitation extremes have used general circulation models, which are poor platforms for studying tropical convection because convection is parameterized. In idealized cloud-resolving simulations, it is possible to identify not only the changes in local precipitation fluxes, but also the factors responsible for those changes. There are many properties of convection that can change as the atmosphere warms, each of which could produce deviations from CC scaling. These properties include the effective water-vapor gradient, cloud pressure depth, and cloud velocity. A simple theory is developed that predicts the changes in these properties consistent with CC scaling. Convection in the cloud-resolving simulations is found to change as predicted by this theory, leading to an ∼20% increase in local precipitation fluxes when the CO2 concentration is doubled. Overall, an increase in CO2 leads to more vigorous convection, composed of clouds that are wider, taller, and faster.

Numerical Archetypal Parameterization for Mesoscale Convective Systems

2016 ◽  
Vol 73 (7) ◽  
pp. 2585-2602 ◽  
Author(s):  
Jun-Ichi Yano ◽  
Mitchell W. Moncrieff
Keyword(s):  
Vertical Shear ◽  
Convective Systems ◽  
Squall Lines ◽  
Starting Point ◽  
Mesoscale Convective ◽  
Transport Kinetic ◽  
Horizontal Momentum ◽  
Multiscale Structures ◽  
Convective Momentum Transport ◽  
Organized Convection

Abstract Vertical shear commonly organizes atmospheric convection into coherent multiscale structures. The associated countergradient vertical transport of horizontal momentum by organized convection can enhance the wind shear and transport kinetic energy upscale. However, organized convection and its upscale effects are not represented by traditional mass-flux-based parameterizations. The present paper sets the archetypal dynamical models, originally formulated by the second author, into a parameterization context by utilizing a nonhydrostatic anelastic model with segmentally constant approximation (NAM–SCA). Using a two-dimensional framework as a starting point, NAM–SCA spontaneously generates propagating tropical squall lines in a sheared environment. High numerical efficiency is achieved through a novel compression methodology. The numerically generated archetypes produce vertical profiles of convective momentum transport that are consistent with the analytic archetype.

scholarly journals Changes in Temperature and Precipitation Extremes in Superparameterized CAM in Response to Warmer SSTs

2017 ◽  
Vol 30 (24) ◽  
pp. 9827-9845 ◽  
Author(s):  
Xin Zhou ◽  
Marat F. Khairoutdinov
Keyword(s):  
Large Scale ◽  
Rain Rate ◽  
Precipitable Water ◽  
Heavy Precipitation ◽  
Global Scale ◽  
Precipitation Extremes ◽  
Temperature And Precipitation ◽  
Hourly Data ◽  
Cloud Resolving Model ◽  
Cold Extremes

Subdaily temperature and precipitation extremes in response to warmer SSTs are investigated on a global scale using the superparameterized (SP) Community Atmosphere Model (CAM), in which a cloud-resolving model is embedded in each CAM grid column to simulate convection explicitly. Two 10-yr simulations have been performed using present climatological sea surface temperature (SST) and perturbed SST climatology derived from the representative concentration pathway 8.5 (RCP8.5) scenario. Compared with the conventional CAM, SP-CAM simulates colder temperatures and more realistic intensity distribution of precipitation, especially for heavy precipitation. The temperature and precipitation extremes have been defined by the 99th percentile of the 3-hourly data. For temperature, the changes in the warm and cold extremes are generally consistent between CAM and SP-CAM, with larger changes in warm extremes at low latitudes and larger changes in cold extremes at mid-to-high latitudes. For precipitation, CAM predicts a uniform increase of frequency of precipitation extremes regardless of the rain rate, while SP-CAM predicts a monotonic increase of frequency with increasing rain rate and larger change of intensity for heavier precipitation. The changes in 3-hourly and daily temperature extremes are found to be similar; however, the 3-hourly precipitation extremes have a significantly larger change than daily extremes. The Clausius–Clapeyron scaling is found to be a relatively good predictor of zonally averaged changes in precipitation extremes over midlatitudes but not as good over the tropics and subtropics. The changes in precipitable water and large-scale vertical velocity are equally important to explain the changes in precipitation extremes.

A Global Atlas of Tropical Precipitation Extremes

2019 ◽  
pp. 1-13
Author(s):  
Brian C. Matilla ◽  
Brian E. Mapes
Keyword(s):  
Precipitation Extremes ◽  
Tropical Precipitation
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