DE-13-018 -- An Analysis of NASA's MERRA Meteorological Data to Supplement Observational Data for Calculation of Climatic Design Conditions PDF

ASHRAE Technical Committee 4.2, Climatic Information,publishes a quadrennial update of climatic design informationin Chapter 14 of the ASHRAE Handbook - Fundamentals(ASHRAE 2009a). The design information for 5564 locationsaround the world is based upon hourly values of dry-bulbtemperature, wet-bulb temperature, dew-point temperature,wind speed and direction, surface pressure, and solar radiation.The 2009 design conditions provided a significantenhancement over the 2005 design conditions with respect tothe global coverage - 5564 locations in 2009 versus 4422 locationsin 2005. The ASHRAE design conditions, based on meteorologicaldata, are calculated using hourly surface data fromstations having a minimum of 8 years of observations, but morestations typically span 25 years of observations; althoughfrequently the time series are discontinuous. The ASHRAEsolar-related design conditions are based on model-derivedsolar radiation. A potential source for both global and timecontiguous meteorological and solar data is NASA’s POWER(Prediction ofWorldwide Energy Resource) web portal (NASA2013a). This includes the recently available meteorologicaldata based on an improved reanalysis model - Modern EraRetrospective-analysis for Research and Applications(MERRA). MERRA yields global, hourly surface meteorologicalparameters for the years 1981 to present. An initial evaluationof the MERRA daily maximum, minimum, and averagedtemperatures indicates accuracies sufficient to warrant theiruse to supplement existing surface observations. In this paper,we present an evaluation of the accuracy of the MERRA dailytemperatures, followed by an assessment of the applicability ofthe MERRA hourly temperatures in the development of annualdry-bulb climate design criteria and annual heating and coolingdegree-days over the continental United States.