Analysis of an Observing System Experiment for the Joint Polar Satellite System

Abstract

he Joint Polar Satellite System (JPSS) is a key contributor to the next-generation operational polar-orbiting satellite observing system. In the JPSS era, the complete polar-orbiting observing system will be composed of two satellites?in the midmorning (mid-AM) and afternoon (PM) orbits?each with thermodynamic sounding capabilities from both microwave and hyperspectral infrared instruments. JPSS will occupy the PM orbit, while the Meteorological Operational (MetOp) system, sponsored by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), will occupy the mid-AM orbit.While the current polar-orbiting satellite system has been thoroughly evaluated, information about its resilience and efficacy in the JPSS era is needed. A 7-month (August 2012?February 2013) observing system experiment (OSE) was run with the National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS). Observations were selected from operational satellite data platforms to be representative of the polar-orbiting data in the JPSS era.Overall, removing data from the PM orbit produced inferior scores, with the impact greater in the Southern Hemisphere (SH) than in either the Northern Hemisphere (NH) or the tropics.For the entire 7 months, the time-mean 500-hPa geopotential height anomaly correlation (Z500AC) decreased by 0.005 and 0.013 in the NH and SH, respectively?both of which are statistically significant at the 95% level. Additionally, a detailed statistical analysis of the distribution of Z500AC skill scores is presented and compared with historical accuracy data. It was determined that eliminating PM orbit data resulted in a higher probability of producing low scores and a lower probability of producing high scores, counter to the trend in GFS forecast skill over the last 20 years.