The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events, and the technical terms clustered index and high clustered region are defined to investig...The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events, and the technical terms clustered index and high clustered region are defined to investigate their temporal and spatial distribution characteristics in China during the past 50 years. The results show that the contribution of extreme high-temperature event clusters changed in the period from the 1960s to the 1970s, and its strength was enhanced. On the other hand, the decreasing trend in the clusters of low-temperature extremes can be taken as a signal for warmer winters to follow in the decadal time scale. Torrential rain and heavy rainfall clusters have both been lessened in the past 50 years, and have different cluster characteristics because of their definitions. Regions with high clustered indexes are concentrated in southern China. The spatial evolution of the heavy rainfall clusters reveals that clustered heavy rainfall has played an important role in the rain-belt pattern over China during the last 50 years.展开更多
An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the l...An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.展开更多
In this study, the winter-summer-winter seasonal variation characteristics of the atmospheric temperature in northern East Asia(NEA) during the past 60 years are analyzed. The results revealed a type of new seasonal v...In this study, the winter-summer-winter seasonal variation characteristics of the atmospheric temperature in northern East Asia(NEA) during the past 60 years are analyzed. The results revealed a type of new seasonal variation mechanism of temperature: winter-winter recurrence(WWR). This study initially discussed the formation mechanism of WWR from the angle of the relationship between the WWR and the atmospheric internal factors and external forcing.The main conclusions are summarized as follows:(1) The winter-summer-winter continuous variation of the AO anomaly index has consistent characteristics with the atmospheric variation of the WWR in the NEA, and their 60-year correlation coefficient reaches 0.43, passing the 95% significance level. It is indicated that the seasonal anomaly of the AO has a certain influence on the WWR;(2) Overall, the PDO maintains a negative phase in the negative WWR years,while it displays the opposite feature in the positive WWR years. The negative(positive) anomaly of PDO is favourable to the occurrence of sustainable low(high) temperatures in the NEA, and may be the important external driving factor for motivating the WWR in the NEA;(3) The binary regression, based on the PDO and AO indexes successfully reproduces the curve of T_(WWR-HG), which is significantly correlated with the WWR index TWWR, and can reproduce the time-height profile of the WWR characteristics from 400 to 1,000 hPa. Therefore, it is concluded that the WWR of the atmospheric temperatures in the NEA is the result of the combined action of the PDO and AO.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.41005043 and 41105033)the National Basic Research Program of China(Grant No.2012CB955901)the National Science and Technology Ministry,China(Grant Nos.2007BAC29B01 and 2007BAC03A01)
文摘The pick-up algorithm by the k-th order cluster for the closest distance is used in the fields of weather and climactic events, and the technical terms clustered index and high clustered region are defined to investigate their temporal and spatial distribution characteristics in China during the past 50 years. The results show that the contribution of extreme high-temperature event clusters changed in the period from the 1960s to the 1970s, and its strength was enhanced. On the other hand, the decreasing trend in the clusters of low-temperature extremes can be taken as a signal for warmer winters to follow in the decadal time scale. Torrential rain and heavy rainfall clusters have both been lessened in the past 50 years, and have different cluster characteristics because of their definitions. Regions with high clustered indexes are concentrated in southern China. The spatial evolution of the heavy rainfall clusters reveals that clustered heavy rainfall has played an important role in the rain-belt pattern over China during the last 50 years.
基金supported by the Special Scientific Research Projects for Public Interest(No.GYHY201006021 and GYHY201106016)the National Natural Science Foundation of China(No.41205040 and 40930952)
文摘An objective identification technique is used to detect regional extreme low temperature events （RELTE） in China during 1960-2009. Their spatial-temporal characteristics are analyzed. The results indicate that the lowest temperatures of RELTE, together with the frequency distribution of the geometric latitude center, exhibit a double-peak feature. The RELTE frequently happen near the geometric area of 30°N and 42°N before the mid-1980s, but shifted afterwards to 30°N. During 1960-2009, the frequency~ intensity, and the maximum impacted area of RELTE show overall decreasing trends. Due to the contribution of RELTE, with long duratioh and large spatial range, which account for 10% of the total RELTE, there is a significant turning point in the late 1980s. A change to a much more steady state after the late 1990s is identified. In addition, the integrated indices of RELTE are classified and analyzed.
基金State Key development program for Basic Research(2017YFC15023003)National Natural Science Foundation of China(41575082,41530531)Special Scientific Research Project for Public Interest(GYHY201306021)
文摘In this study, the winter-summer-winter seasonal variation characteristics of the atmospheric temperature in northern East Asia(NEA) during the past 60 years are analyzed. The results revealed a type of new seasonal variation mechanism of temperature: winter-winter recurrence(WWR). This study initially discussed the formation mechanism of WWR from the angle of the relationship between the WWR and the atmospheric internal factors and external forcing.The main conclusions are summarized as follows:(1) The winter-summer-winter continuous variation of the AO anomaly index has consistent characteristics with the atmospheric variation of the WWR in the NEA, and their 60-year correlation coefficient reaches 0.43, passing the 95% significance level. It is indicated that the seasonal anomaly of the AO has a certain influence on the WWR;(2) Overall, the PDO maintains a negative phase in the negative WWR years,while it displays the opposite feature in the positive WWR years. The negative(positive) anomaly of PDO is favourable to the occurrence of sustainable low(high) temperatures in the NEA, and may be the important external driving factor for motivating the WWR in the NEA;(3) The binary regression, based on the PDO and AO indexes successfully reproduces the curve of T_(WWR-HG), which is significantly correlated with the WWR index TWWR, and can reproduce the time-height profile of the WWR characteristics from 400 to 1,000 hPa. Therefore, it is concluded that the WWR of the atmospheric temperatures in the NEA is the result of the combined action of the PDO and AO.
