The robust dynamical contribution to precipitation extremes in idealized warming simulations across model resolutions

Abstract

The impact of the circulation shift under climate warming on the distribution of precipitation extremes and the associated sensitivity to model resolution are investigated using Community Atmosphere Model Version 3.0 in an aquaplanet configuration. The response of the probability density function of the precipitation to a uniform sea surface temperature warming can be interpreted as superimposition of a dynamically induced poleward shift and a thermodynamically induced upward shift toward higher intensities, which give rise to manyfold increase in the frequency of the most extreme categories of the precipitation events at the poleward side of the midlatitude storm track. Coarser resolutions underestimate not only the intensity of the precipitation extremes but also the dynamical contribution to the increase of precipitation extremes. Meanwhile, the thermodynamic contribution to the intensification of the precipitation extremes is substantially less than expected from the Clausius-Clapeyron relation, implicative of significant change in the vertical structure of the precipitation processes.

Changing circulation structure and precipitation characteristics in Asian monsoon regions: greenhouse warming vs. aerosol effects

“…By comparing ALL to GHG, the extent to which GHG-induced anomalies are modulated by aerosols will be assessed. Changes in rainfall characteristics will be explored using scale analysis based on water balance requirement (Sugiyama et al 2010;Lu et al 2014) and quantile regression analysis (Buchinsky 1998;Wu 2006, 2011), as well as compared observations from APHRODITE (Yatagai et al 2012).…”

“…Specifically, we will focus on changes in precipitation efficiency and rainfall types. Here, the change in precipitation efficiency will be examined via a scale analysis, based on the water balance requirements (Sugiyama et al 2010;Lu et al 2014). In ASM regions, where the climatological mean vertical motion is upward, the area mean precipitation, P, can be expressed as:…”

“…(1) yields (1) P = αMq, where we have assumed that dM M ∼ dw w , with w representing the vertical motion at the 500 hPa level, which signifies the strength of the MMC. Since cloud base information for each CMIP5 model is not available, the approximation of cloud mass flux by vertical moisture flux at the mid-and lower troposphere has been used in many previous climate-scale rainfall scale analysis (Held and Soden 2006;Sugiyama et al 2010;Lu et al 2014). The fractional change of area mean values of P, w, q for each simulated year from 1870 to 2005 (Fig.…”

Simultaneous characterization of mesoscale and convective‐scale tropical rainfall extremes and their dynamical and thermodynamic modes of change

“…In addition, it can be demonstrated that the largest departures from CC observed in CAM5 are probably unrealistic, assuming that the Earth's tropics are in RCE. First, tropical extreme rainfall rates may be approximated by [ Lu et al ., ; MOE11]. Second, we assume that the strongest vertical velocities w max increase with the convective available potential energy (CAPE) as .…”

“…GCMs simulate the large‐scale circulation and show a rich variety of sea‐surface temperature (SST) patterns and other emergent phenomena. However, most current GCMs feature relatively coarse horizontal resolutions of O (100 km ), and the resulting reliance on diverse and uncertain parameterizations of deep convection leads to biased precipitation statistics [ Dai , ; Stephens et al ., ; Kopparla et al ., ; Lu et al ., ; O'Brien et al ., ]. CRMs use finer grid spacings of a few km at most that allow realistic representations of convective dynamics, but the resulting much higher computational costs has usually imposed serve constraints on the spatial and temporal domains accessible to simulation.…”