Global Warming Impacts on Mid-Latitude Cyclone Precipitation in the NARCCAP Model Suite

A topic which is gaining an increasing amount of attention from the climate community is the role that synoptic-scale storms play in the current and future climate. Mid-latitude cyclones have significant socioeconomic impacts due to their effects on agriculture, industry, transportation, and the general public. This research assesses how rainfall is altered in mid-latitude cyclones in the North American Regional Climate Change Assessment Program (NARCCAP) suite of models. The NARCCAP models are unique, because they are composed of regional climate models (RCMs) driven by ocean general circulation models (AOGCMs) over the United States and much of Canada. Two climate scenarios are presented: The first is for the current climate from 1971-2000 and the second is from the SRES A2 scenario from 2041-2070. Storms are tracked via the sea-level pressure field (SLP) with subsequent rainfall tracking achieved via a polar-projection, which has the advantage of conserving area as cyclones track latitudinally. Precipitation-tracking is performed over several regions of the NARCCAP domain chosen in proximity to active storm tracks. Results are also shown for the ERA-Interim renanalysis data. A comparison of mid-latitude cyclone-associated precipitation between the current and A2 climates will show a systemic tendency towards wetter storms in the A2 scenario over several regions and at various intensities. These results support the idea that more extreme precipitation events will occur as the climate continues to warm.