Published: Response of Extreme Precipitating Cell Structures to Atmospheric Warming

Good news! Recently, we published (open access) another article about the response of extreme precipitation to atmospheric warming.

Abstract

With increasing temperatures, it is likely that precipitation extremes increase as well. While, on larger spatial and longer temporal scales, the amplification of rainfall extremes often follows the Clausius‐Clapeyron relation, it has been shown that local short‐term convective precipitation extremes may well exceed the Clausius‐Clapeyron rate of around 6.5%/K. Most studies on this topic have focused exclusively on the intensity aspect, while only few have examined (with contradictory results) how warmer and moister conditions modulate the spatial characteristics of convective precipitation extremes and how these connect to increased intensities. Here we study this relation by using a large eddy simulation model. We simulate one diurnal cycle of heavy convective precipitation activity based on a realistic observation‐based strongly forced case setup. Systematically perturbed initial conditions of temperature and specific humidity enable an examination of the response of intensities and spatial characteristics of the precipitation field over an 8° dew point temperature range. We find that warmer and moister conditions result in an overall increase of both intensities and spatial extent of individual rain cells. Colder conditions favor the development of many but smaller rain cells. Under warmer conditions, we find a reduced number of individual cells, but their size significantly grows along with an increase of intensities over a large part of a rain cell. Combined, these factors lead to larger and more intense rain cells that can produce up to almost 20% more rain per degree warming and therefore have a large impact.

Lochbihler, K., Lenderink, G., & Siebesma, A. P. ( 2019). Response of extreme precipitating cell structures to atmospheric warming. Journal of Geophysical Research: Atmospheres, 124, 6904– 6918. https://doi.org/10.1029/2018JD029954

Published: The spatial extent of rainfall events and its relation to precipitation scaling

I’m glad to announce that my first paper was published in Geophysical Research Letters. A link to the official GRL page is at the bottom of this post. You can also find it in the TU Delft repository.

Abstract

Observations show that subdaily precipitation extremes increase with dew point temperature at a rate exceeding the Clausius-Clapeyron (CC) relation. The understanding of this so-called super CC scaling is still incomplete, and observations of convective cell properties could provide important information. Here the size and intensity of rain cells are investigated by using a tracking of rainfall events in high-resolution radar data. Higher intensities are accompanied by larger rainfall areas. However, whereas small rain cells mainly follow CC scaling, larger cells display super CC behavior. Even more, for dew point exceeding 15°C, the rain cell size has to increase in order to sustain super CC scaling and a remarked increase in rain cell area is found. Our results imply that the source area of moisture, the cloud size, and the degree of mesoscale organization play key roles in the context of a warming climate.

Lochbihler, K., G. Lenderink, and A. P. Siebesma (2017), The spatial extent of rainfall events and its relation to precipitation scaling, Geophys. Res. Lett., 44, 8629–8636, doi:10.1002/2017GL074857.