How will orographic precipitation respond to surface warming? An idealized thermodynamic perspective

Abstract

Future changes in orographic precipitation will have important consequences for societies and ecosystems near mountain ranges. Here we use a simple numerical model to evaluate the response of orographic precipitation to surface warming under idealized conditions representative of the strongest orographic storms. We find an upward shift in the pattern of condensation with warming, caused by larger fractional changes in condensation at low temperature and amplified warming aloft. As a result, the distribution of precipitation shifts downwind, causing larger fractional changes in precipitation on the lee slope than on the windward slope. Total precipitation is found to increase by a smaller fraction than near‐surface water vapor, in contrast to expected changes in other types of extreme precipitation. Factors limiting the increase in orographic precipitation include the pattern of windward ascent, leeside evaporation, and thermodynamic constraints on the change in condensation with temperature.

Sensitivity of historical orographically enhanced extreme precipitation events to idealized temperature perturbations

“…For warm cloud processes, the precipitation growth is dominated by the collision-coalescence process. However, as shown in both Kirshbaum and Smith (2008) and Siler and Roe (2014) the increase in condensation rate is less than the increase in atmospheric water vapor. In other words, the air needs to be lifted further up to reach condensation.…”

“…Allan and Ingram 2002;Trenberth et al 2003;Pall et al 2006;Loriaux et al 2013). By using a simple numerical model for idealized extreme storms, Siler and Roe (2014) found that orographic precipitation had a lower response to surface warming than expected by the CC-relation. They noted a decrease in the condensation rate combined with an increase in transport of precipitation to the lee side of the mountain, where evaporation occurs, as the main reasons Abstract Using high resolution convective permitting simulations, we have investigated the sensitivity of historical orographically enhanced extreme precipitation events to idealized temperature perturbations.…”

“…5). The increased relative sensitivity in high elevation areas may be a result of the larger fractional change in condensation with lower temperatures as a result of the temperature dependence of CC's equation (Siler and Roe 2014). Regionally there are large percentage increases along the fjords located in areas of relative steep topography in the inland area with values above 15%/K (Fig.…”

A 133-Year Record of Climate Change and Variability from Sheffield, England

“…In addition, we have not discussed the potential influence of the Pennine Mountains to the west of Sheffield in influencing precipitation by orographic enhancement. A warmer climate might result in a shift of precipitation downwind in orographic regions [47]. Many storms that cross the UK do so from the southwest, so this factor could enhance precipitation rates across WP and rain-shadow regions of the UK.…”

Characteristics of rainfall events in regional climate model simulations for the Czech Republic

“…Fowler and Ekström, 2009;Herrera et al, 2010;Buishand, 2011, 2012;Rajczak et al, 2013;Bartholy et al, 2015;Danandeh Mehr and Kahya, 2016). Although growing attention has been given to studies at sub-daily timescales in recent years, the complexity of physical processes related to sub-daily extremes (Stocker et al, 2013;Siler and Roe, 2014) and their simplification within climate model parameterizations make assessment of simulated sub-daily precipitation challenging, particularly since its validation is impaired by the lack of long and high-quality observed rainfall data series at hourly or sub-hourly timescales with sufficient spatial coverage allowing for comparison to simulated (spatial average) rainfall (Westra et al, 2014).…”