Climatic Change Of Temperature And Precipitation Under Various Station Networks In China

In order to monitor, forecast and analysis climate change, China set up ground-based observatoriesin different grade and density such as the national basic meteorological station, the nationalreference climatological station and the national general meteorological station. A large number ofstudies for climate change have shown that the element changes obtained by different researchersin the same area, the same period are different. The reason can be found that the researchers useddifferent station network, which should be the main factors that lead to different results. Researchanalysis whether various meteorological monitoring network can meet the requirements of themonitoring of climate change is important. And the differences of climate monitoring undervarious stations network and the monitoring representative of different station network for theclimate state, climate change and extreme events is practically significant for the construction offuture ground Climate Observing System, regional climate change monitoring and analysis.Therefore, based on temperature and precipitation data during1961-2010, a comparative analysisof changes of the air temperature, precipitation, extreme events and their change were studiedunder different observation stations. The main conclusions are as follows:(1) The results for the50-year average nationwide temperature climate state vary in differentstation network. The series obtained by the basic and references is the most close to the standardseries among the stations network. For spatial distribution of the average temperature, the basicand reference station is monitoring better, but the detail value differs in different area. Themonitoring differences in most of the South and North area are controlled within10%.Meteorological stations at all levels are able to monitor the rising trend of average temperature ofChina, but the monitoring rates are different. Whether the spatial distribution of the trends or theoverall temperature rise rate, the basic and reference station network monitors the best.(2) The annual precipitation values in China at various station networks are consistent. Themonitoring difference of the basic and reference station is the smallest. Spatial distribution ofannual precipitation in various stations network could describe the distribution in the form ofincreased precipitation from northwest to southeast. And it is bounded to the400mm precipitation line, and monitoring values to the east are larger and the differences are smaller while values tothe west are smaller and the differences are larger. For precipitation anomaly percentage changetrend, monitoring difference of the basic station is the smallest. The monitoring difference of basicand reference station is the smallest for the spatial patterns of precipitation trends.(3) The basic and reference station, the basic station and the reference station can be used forthe climatic state of the annual extreme high temperature frequency during1961-2010. The timeseries of extreme high temperature frequency monitored by the basic and reference station and thebasic station are most close to the standard sequence. For the spatial distribution of the changetrends of frequency, the national basic and reference station is monitored better. At all levels ofnetwork the spatial distribution of the main modal of extreme high temperature frequency EOFanalysis is of certain similar. The extreme high temperature frequencies consistently increase inmost of China, but the high-value centers of the low-density station network differ from thestandard station network. In addition, the frequency changes of the low-density station networkare closely related to the changes of circulation.(4) For the monitoring of the climate average value of extreme low temperature frequencynumber during1961-2010, the relative differences of four station networks do not exceed2%sothe four station networks can be used in the research of climatic state of extreme low temperaturefrequency. On the climatic change, the time series of extreme low temperature frequency for fourstation networks are all close to the series of the standard sequence, and the correlationcoefficients are over0.95. For the spatial distribution of the change trends of frequency, all stationnetworks are able to describe the downward trend in most of China. The trends are smaller inShaanxi, Chongqing, the central of Northeast and west of Tibet, while the other regions are larger.The spatial distribution of the main modal of extreme low temperature frequency EOF analysiscan show the characteristics that the changes of extreme low temperature frequency are consistentunder various station networks. However, the central intensity of low density station networks ishigher than the standard station network.(5) For the monitoring of the climate average value of extreme heavy precipitation frequencynumber during1961-2010, the relative differences of four station networks do not exceed5%sothe four station networks can be used in the research of climatic state of extreme heavyprecipitation frequency. On the climatic change, the time series of extreme low temperature frequency for the basic and reference station, the basic station and the reference station are closeto the series of the standard sequence, and the correlation coefficients are over0.9. For the spatialdistribution of the change trends of frequency, all station networks are able to describe thecharacteristics that bounded to the100E line the trends to the east are smaller while the trends tothe west are larger. The spatial distribution of the main modal of extreme high precipitationfrequency EOF analysis can show the characteristics that the changes of extreme highprecipitation frequency are consistent under various station networks. However, the high valueareas of the basic and reference station and the basic station are different from the standard stationnetwork. The high value area in Eastern China is related to the circulation change, but except forthe effect of circulation, the station number, the station composition, topography and so on are alsothe reason of the change of the extreme high precipitation frequency.