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Liu Y.,Chengdu University of Information Technology | Duan Q.,Beijing Normal University | Zhao L.,Public Meteorological Service Center | Ye A.,Beijing Normal University | And 4 more authors.
Hydrological Processes | Year: 2013

The National Center for Environmental Predictions (NCEP) has produced an ensemble meteorological reforecast product by using a fixed version of Global Forecast System (GFS) ensemble prediction system since 1 January 1979. The 15-member ensemble product, with a global coverage at a 2.5°×2.5° spatial resolution and a 14-day lead time, has been used successfully by the River Forecast Centers of the National Weather Service (NWS) to produce basin scale precipitation and temperature ensemble forecasts in the US for several years now. This study evaluates the predictive skill of post-processed ensemble forecasts based on GFS precipitation reforecast in China's Huai river basin. The evaluation is carried out in 15 sub-areas of the Huai river basin and covers the 1/1/1981-31/12/2003 period. The Ensemble Pre-Processing system version 3 (EPP3), developed at NWS, is used to develop joint probability distributions between forecasted ensemble mean precipitation and corresponding observations and to generate individual ensemble members that preserve space-time correlation of the observed precipitation data. Several statistical verification measures are used to quantify the goodness of fit between post-processed (i.e. EPP3 processed) ensemble mean and observation and to assess the ensemble spread. Results indicate that the post-processed forecasts have meaningful predictive skill for the first few days for ensemble daily precipitation forecasts. Predictive skill of ensemble forecasts of cumulative precipitation for lead times up to 14days are significant. The forecast skill is highly dependent on seasonality, with relatively lower skills seen for wet summer season, when convective storm patterns dominate, as compared with other seasons. The predictive skill of the post-processed ensemble precipitation is much better than the raw forecasts and the climatological ensemble forecasts. The results from this study suggest that the NCEP's GFS reforecasts can be a valuable resource for places other than the US. © 2012 John Wiley & Sons, Ltd. Source

Feng L.,CAS Institute of Atmospheric Physics | Feng L.,Public Meteorological Service Center | Zhou T.,CAS Institute of Atmospheric Physics
Journal of Geophysical Research: Atmospheres | Year: 2012

The atmospheric water vapor transport for summer precipitation over the southeastern Tibetan Plateau (hereafter TP) during 1979-2002 is examined by using five precipitation data sets and three reanalysis data sets. The multidata ensemble mean shows that under climate mean conditions, TP is a moisture sink in summer, having a net moisture convergence of 4 mm/day. The climatological water vapor transport from the southern boundary, which originates from the Indian Ocean and the Bay of Bengal, dominates the summer precipitation over the southeastern TP. It is estimated that the water vapor from the western boundary along the southern edge of the TP is about 32% of that from the southern boundary. The summer precipitation over the southeastern TP exhibits strong interannual variability, with a standard deviation of 1.3 mm/day, but no significant long-term trend. The water vapor transport for the interannual variability of summer rainfall over the southeastern TP mainly comes from the western boundary of the TP, which is originally from lower latitudes. An excessive rainfall anomaly of 1 mm/day over the southeastern TP is associated with an anomalous water vapor input of 138 (104) kg/m/s from the western (southern) boundary. It is worth noting that the quantitative analysis in this study is determined by the setting of the domain. The interannual variability of summer precipitation over the southeastern TP is dominated by an anomalous anticyclone over the northern Indian subcontinent and the Bay of Bengal, which intensifies the water vapor transport along the southern edge of the TP and leads to more water vapor convergence over the southeastern TP, thus the excessive rainfall in the area. © 2012. American Geophysical Union. All Rights Reserved. Source

Shen Y.-B.,Center for Wind and Solar Energy Resources Assessment | Shen Y.-B.,Public Meteorological Service Center | Wang B.,CAS Institute of Atmospheric Physics
Chinese Journal of Geophysics (Acta Geophysica Sinica) | Year: 2011

Most of Earth's surface energy is from solar, and the change of surface solar radiation will profoundly affect the global climate. In this paper, the synchronous observational data of global radiation and temperature from 14 stations in South-East China was used to analyse the probable influence of surface solar radiation change on temperature change from 1961 to 2008. During 1961 - 1989, surface solar radiation in South-East China was significantly weakened, resulting in a slight decrease of average temperature. During 1993-2008, surface solar radiation in South-East China was increased, which was superposed on the other warming effects and accelerated the increase of temperature. In a word, the surface solar radiation change plays an essential role in the climate change in South-East China during these 50 years. Source

Tang Q.,Public Meteorological Service Center | Xie L.,North Carolina State University | Lackmann G.M.,North Carolina State University | Liu B.,North Carolina State University
Advances in Meteorology | Year: 2013

The contribution of the large-scale atmospheric environment to precipitation and flooding during Hurricane Floyd was investigated in this study. Through the vortex removal technique in the Weather Research and Forecasting (WRF) model, the vortex associated with Hurricane Floyd (1999) was mostly removed in the model initial conditions and subsequent integration. Results show that the environment-induced precipitation can account for as much as 22% of total precipitation in the innermost model domain covering North Carolina coastal area and 7% in the focused hydrological study area. The high-resolution precipitation data from the WRF model was then used for input in a hydrological model to simulate river runoff. Hydrological simulation results demonstrate that without the tropical systems and their interactions with the large-scale synoptic environment the synoptic environment would only contribute 10% to the total discharge at the Tarboro gauge station. This suggests that Hurricane Floyd and Hurricane Dennis preceding it, along with the interactions between these tropical systems and the large-scale environment, have contributed to the bulk (90%) of the record amount of flood water in the Tar-Pamlico River Basin. © 2013 Qianhong Tang et al. Source

Wang L.,Capital Normal University | Gong H.,Capital Normal University | Liao W.,Sun Yat Sen University | Wang Z.,Public Meteorological Service Center
Science of the Total Environment | Year: 2015

Plants can effectively remove airborne particles from ambient air and consequently improve air quality and human health. The accumulation of particles on the leaf surfaces of three plant species with different epicuticular wax ultrastructures, such as thin films, platelets and tubules, was investigated during leaf expansion in Beijing under extremely high particulate matter (PM) concentration. The accumulation of particles on the leaf surfaces after bud break rapidly reached a high amount within 4-7days. Rainfall occasionally resulted in a considerable increase in the accumulation of particles on the leaf surfaces at a high PM concentration, which resulted from the wet deposition of PM, and balanced the amount of PM on the leaf surfaces over a longer period. The equilibrium value of the particle cover area on the adaxial leaf surface of the three test species in this study was 10%-50% compared with 3%-35% on the abaxial leaf surface. The epicuticular wax ultrastructures contributed significantly to the PM adsorption of the leaves. The capability of these ultrastructures to capture PM decreased in the following order: thin films, platelets and tubules. The ridges (at a scale of 1-2μm) on the leaf surfaces were more efficient at accumulating PM, particularly PM2.5, compared with the roughness (P-V distance) at a 5-20-μm scale. © 2015 Elsevier B.V. Source

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