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Cai J.,Nanjing University of Information Science and Technology | Guan Z.,Nanjing University of Information Science and Technology | Gao Q.,Nanjing University of Information Science and Technology | Lin X.,Fujian Climate Center | Qian D.,Nanjing University of Information Science and Technology
Journal of Geographical Sciences | Year: 2010

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer. © 2010 Science in China Press and Springer-Verlag Berlin Heidelberg. Source


Zou Y.,Chinese Academy of Meteorological Sciences | Zou Y.,Fujian Climate Center | Zhao P.,National Meteorological Information Center
Journal of Tropical Meteorology | Year: 2010

This is a study to compare three selected tropical cyclone datasets separately compiled by CMA Shanghai Typhoon Institute (CMA SHI), the Joint Typhoon Warning Center (JTWC), and the Japan Meteorological Agency (JMA). The annual frequencies, observation times and destructive power index as the characteristic quantities are investigated of the tropical cyclones over the western North Pacific. The comparative study has resulted in the following findings: 1) Statistical gaps between the datasets compared are narrowing down as the intensity of tropical cyclones increases. 2) In the context of interdecadal distribution, there is for the 1950s a relatively large gap between the datasets, as compared with a narrowed gap for the period from the mid 1970s to the 1980s, and a recurring widened gap for the mid and late 1990s. Additionally, an approach is proposed in the paper to correct the wind speed data in the TC Yearbook. Source


Gao J.,Fujian Climate Center | Li T.,University of Hawaii at Manoa
Advances in Atmospheric Sciences | Year: 2012

The interannual variability of occurrence of multiple tropical cyclone (MTC) events during June-October in the western North Pacific (WNP) was examined for the period 1979-2006. The number of the MTC events ranged from 2 to 9 per year, exhibiting a remarkable year-to-year variation. Seven active and seven inactive MTC years were identified. Compared to the inactive years, tropical cyclone genesis locations extended farther to the east and in the meridional direction during the active MTC years. A composite analysis shows that inactive MTC years were often associated with the El Niño decaying phase, as warm SST anomalies in the equatorial eastern-central Pacific in the preceding winter transitioned into cold sea surface temperature (SST) anomalies in the concurrent summer. Associated with the SST evolution were suppressed low-level cyclonic vorticity and weakened convection in the WNP monsoon region. In addition to the mean flow difference, significant differences between active and inactive MTC years were also found in the strength of the atmospheric intraseasonal oscillation (ISO). Compared with inactive MTC years, ISO activity was much stronger along the equator and in the WNP region during active MTC years. Both westward- and northward-propagating ISO spectrums strengthened during active MTC years compared to inactive years. The combined mean state and ISO activity changes may set up a favorable environment for the generation of MTC events. © 2012 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg. Source


Yin Y.,Tsinghua University | Gemmer M.,National Climate Center | Su B.,National Climate Center | Luo Y.,Tsinghua University | And 2 more authors.
Journal of Natural Disasters | Year: 2012

Weather index insurance is a method for risk transfer and is widely studied around the world. It can avoid the limitations of traditional insurance for natural disasters and can be applied to the field of agriculture. This study took Lianjiang County in Fujian Province as an example to found a weather index for typhoon disaster with meteorological data. Based on the characteristics of typhoon disasters and activities in Lianjiang County, the typhoons that could cause certain loss to the Lianjiang County are divided into three types ¡strong wind, heavy rainfall , and strong wind plus heavy rainfall dominated respectively. Finally, the frame of weather index insurance for typhoon disaster in Lianjiang County was established based on the meteorological data and probability distribution. Source


Sun P.,Hubei Meteorological Service Center | Sun P.,Hubei Province Meteorological Energy Technology Development Center | Chen Z.,Hubei Meteorological Service Center | Chen Z.,Hubei Province Meteorological Energy Technology Development Center | And 5 more authors.
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2015

Model output statistics (MOS) is a relatively simple and reliable method for forecasting solar radiation. Based on improved conventional MOS method, a improved radiation forecast model was set up to improve the forecasting effect. Considering the weakening effect of atmosphere on radiation, the actual radiation was converted to articulation index to remove astronomical solar radiation impact. Besides, owing to greater impacts of different weather conditions on solar radiation, weather type was classified by using Fisher method before modeling. Meteorological elements of the same weather type, at the same times and in the same season were regarded as a same type. Considering weight changes of solar radiation elements resulted by seasonal and diurnal change characteristics of the solar radiation, the forecast model for different seasons and different times was built. Finally, considering the continuity of the system error, the error of initial model forecast value and the actual value could be regarded as a variable which would be used to build later hours forecast equation. The results show that the analog values of the model can reflect the actual changes in solar radiation and meet the modeling requirement. The mean absolute percentage error (MAPE) of improved MOS model is about 20% less than that of conventional MOS model, significantly improving the forecasting results. August 2012 as the forecast period, the MAPE is 28.33% in forecast period, and the rRMSE is 16.20%. These results show a good prediction skill of the model. © 2015, Science Press. All right reserved. Source

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