A proxy for high-resolution regional reanalysis for the Southeast United States: assessment of precipitation variability in dynamically downscaled reanalyses

• Published in: Climate dynamics Vol. 38; no. 11-12; pp. 2449 - 2466
• Main Authors: Stefanova, Lydia, Misra, Vasubandhu, Chan, Steven, Griffin, Melissa, O’Brien, James J., Smith III, Thomas J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2012; Springer; Springer Nature B.V
• Subjects: Atmospheric circulation; Climate change; Climatology; Dynamic meteorology; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Geophysics/Geodesy; Marine; Meteorology; Oceanography; Precipitation; Precipitation variability; Sea breezes; Seasonal distribution; Simulation; Summer; Thunderstorms; Water in the atmosphere (humidity, clouds, evaporation, precipitation); Southeastern U.S; United States; Eastern U.S; United Kingdom; ASW, USA, Florida; USA, Southeast; Southeast US; Seasonal variability; Precipitation; Dynamical downscaling; Reanalysis; Hydroclimate; Diurnal variability; diurnal variations; Proxy; atmospheric precipitation; Intraseasonal variation; Scale reduction; Regional scope; Summer; North America; Hydroclimatology; Dynamic method; high resolution
• ISSN: 0930-7575; 1432-0894
• DOI: 10.1007/s00382-011-1230-y

We present an analysis of the seasonal, subseasonal, and diurnal variability of rainfall from COAPS Land–Atmosphere Regional Reanalysis for the Southeast at 10-km resolution (CLARReS10). Most of our assessment focuses on the representation of summertime subseasonal and diurnal variability. Summer precipitation in the Southeast United States is a particularly challenging modeling problem because of the variety of regional-scale phenomena, such as sea breeze, thunderstorms and squall lines, which are not adequately resolved in coarse atmospheric reanalyses but contribute significantly to the hydrological budget over the region. We find that the dynamically downscaled reanalyses are in good agreement with station and gridded observations in terms of both the relative seasonal distribution and the diurnal structure of precipitation, although total precipitation amounts tend to be systematically overestimated. The diurnal cycle of summer precipitation in the downscaled reanalyses is in very good agreement with station observations and a clear improvement both over their “parent” reanalyses and over newer-generation reanalyses. The seasonal cycle of precipitation is particularly well simulated in the Florida; this we attribute to the ability of the regional model to provide a more accurate representation of the spatial and temporal structure of finer-scale phenomena such as fronts and sea breezes. Over the northern portion of the domain summer precipitation in the downscaled reanalyses remains, as in the “parent” reanalyses, overestimated. Given the degree of success that dynamical downscaling of reanalyses demonstrates in the simulation of the characteristics of regional precipitation, its favorable comparison to conventional newer-generation reanalyses and its cost-effectiveness, we conclude that for the Southeast United states such downscaling is a viable proxy for high-resolution conventional reanalysis.