Sensitivity of Midlatitude Heavy Precipitation to SST: A Case Study in the Sea of Japan Area on 9 August 2013

Abstract

This study investigates the influence of sea surface temperature (SST) over the Sea of Japan on a heavy precipitation event that occurred over the northern part (Northern Tohoku region) of Japan's largest island on 9 August 2013. Sensitivity experiments with the Weather Research and Forecasting model show that warmer (cooler) SSTs prescribed over the Sea of Japan in the simulations lead to an increase (decrease) in 24‐hr precipitation averaged within the Northern Tohoku region, especially on the Sea of Japan (i.e., windward) side. Though no significant relationship is found between the local maxima and SSTs over the Sea of Japan, those SST values over the Sea of Japan affect the evolution of the intense convective precipitation; higher (lower) SSTs act to shift the location of intense precipitation on the upwind (downwind) side in the present event. The different evolution results in a different interaction with the downstream orography, leading to no significant relationship between the local maxima of intense precipitation and SSTs. The differences arise from the sensitivity of convective updraft to SSTs. The simulations thus suggest that uncertainties in currently available SST products may alter both the area‐averaged precipitation and the geographical locations of intense precipitation, which can potentially impact flash flood and landslide warnings.

Intra-annual variability of the Western Mediterranean Oscillation (WeMO) and occurrence of extreme torrential precipitation in Catalonia (NE Iberia)

“…Episodes involving ≥ 100 mm in 24 h are more frequent but sometimes have no direct impact or quite a negligible effect, because other factors are the main drivers of floods, e.g. precipitation duration (Jang, 2015), initial soil moisture conditions and hydrological parameters (Norbiato et al, 2008;Martina et al, 2009). Furthermore, the area affected by episodes of ≥ 100 mm in 24 h is sometimes local and is therefore not easily associated with advective synoptic patterns (Gilabert and Llasat, 2018).…”

“…Seawater constitutes an energy store, i.e. recharge areas, which can influence water vapour content and can intensify precipitation episodes (Pastor et al, 2018;Iizuka and Nakamura, 2019) by means of a sea-atmosphere moisture exchange. Furthermore, a significant release of latent heat occurs during atmospheric convection over a warm sea like the Mediterranean at the end of summer and the beginning of autumn (Pastor et al, 2015).…”

Observational evidence of the preferential occurrence of wind convergence over sea surface temperature fronts in the Mediterranean

“…Particular attention has been devoted to the role that SST structures have on heavy precipitation events in the Mediterranean, where widespread coastal urbanisation leads to large exposure of population and infrastructure to intense weather events. While the total amount of rain is not influenced much by the spatial resolution of the SST forcing field (Millán et al ., ; Pastor et al ., ; Lebeaupin et al ., ; Cassola et al ., ), numerical studies show that the spatial structure of the heat fluxes and the position of the rain bands can be influenced (Katsafados et al ., ; Ricchi et al ., ; Rainaud et al ., ; Meroni et al ., ; Iizuka and Nakamura, ). The landward moisture fluxes can also be influenced by the mesoscale SST structures on seasonal scales, as shown by the numerical work of Desbiolles et al .…”

Kuroshio-Enhanced Convective Rainband Associated with an Extratropical Cyclone in the Cold Season

“…Recent studies have shown that the midlatitude ocean, especially the Kuroshio Current, is critical to the occurrence of heavy rainfall events around Japan (Miyama et al 2012;Manda et al 2014;Iizuka and Nakamura 2019;Sekizawa et al 2019;Yamamoto 2020). Miyama et al (2012) examined a convective rainband that developed along the Kuroshio Current over the East China Sea in May 2010 and found that the high sea surface temperature (SST) of the Kuroshio Current intensified the rainband by decreasing static stability.…”