Search

Drought is associated with severe societal impacts ranging from shortages of water for human consumption to agricultural failure and famine. An important aspect of drought forecast is determining the onset, which is critical for early warning efforts and water resources and agriculture planning. Indices of precipitation shortage have been widely used to detect the onset of drought because precipitation deficits often lead to shortages in other hydrologic variables such as soil moisture and runoff. The present work demonstrates that atmospheric temperature and humidity observations from the Atmospheric Infrared Sounder (AIRS) contain information that can be used to detect drought onset earlier than that obtained from precipitation deficit. By calculating the standardized indices for precipitation, near-surface temperature, vapour pressure deficit, and relative humidity, we show that in many regions of the world signals of drought onset can be detected from near-surface temperature and humidity data a few months earlier than those obtained from precipitation deficit. In particular, vapour pressure deficit showed higher effectiveness than relative humidity or temperature only. The outcome was generally consistent for the three- and six-month accumulations studied here. Further analysis using 65 years (1960–2014) of monthly temperature and humidity data derived from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) data set over the continental United States suggests that there is a good agreement between drought early detection signals obtained from AIRS and that from ground stations during the overlapped (2003–2014) period. Analysis using longer record suggests that the frequency of successful early detection of drought onset using temperature and humidity data shows regional shift towards eastern United States in the recent years. [ABSTRACT FROM PUBLISHER]

The Atmospheric Infrared Sounder (AIRS) and its two companion microwave sounders, AMSU and HSB were launched into polar orbit onboard the NASA Aqua Satellite in May 2002. NASA required the sounding system to provide high-quality research data for climate studies and to meet NOAA's requirements for improving operational weather forecasting. The NOAA requirement translated into global retrieval of temperature and humidity profiles with accuracies approaching those of radiosondes. AIRS also provides new measurements of several greenhouse gases, such as CO2, CO, CH4, O3, SO2, and aerosols. The assimilation of AIRS data into operational weather forecasting has already demonstrated significant improvements in global forecast skill. At NOAA/NCEP, the improvement in the forecast skill achieved at 6 days is equivalent to gaining an extension of forecast capability of six hours. This improvement is quite significant when compared to other forecast improvements over the last decade. In addition to NCEP, ECMWF and the Met Office have also reported positive forecast impacts due AIRS. AIRS is a hyperspectral sounder with 2,378 infrared channels between 3.7 and 15.4 µm. NOAA/NESDIS routinely distributes AIRS data within 3 hours to NWP centers around the world. The AIRS design represents a breakthrough in infrared space instrumentation with measurement stability and accuracies far surpassing any current research or operational sounder. The results we describe in this paper are “work in progress,” and although significant accomplishments have already been made much more work remains in order to realize the full potential of this suite of instruments. [ABSTRACT FROM AUTHOR]