The interannual variability of winter and spring precipitation in South China(SC)and its relation to moisture transport are investigated by using the monthly precipitation data of NMIC,NCEP reanalysis datasets and NOA...The interannual variability of winter and spring precipitation in South China(SC)and its relation to moisture transport are investigated by using the monthly precipitation data of NMIC,NCEP reanalysis datasets and NOAA ERSST analysis datasets from 1960 to 2008.The results show that winter and spring precipitation in SC is less than normal from the 1960s to the start of the 1970s and from the end of the 1990s to the present.Most of rainfall anomalies on the whole regional scale of SC is well in phase during winter and spring,and the frequency of persistent drought is higher than that of persistent flood.Seasonal variations of moisture transport differences of SC between persistent drought and flood events are observed:the differences in winter are characterized by moisture transport from Bay of Bangle(BOB)and South China Sea(SCS),while differences in spring are characterized by that from SCS and North China(NC).There are two types of Ni o3.4 sea surface temperature anomaly(SSTA)related to persistent winter and spring drought(flood)events in SC,which are positive SSTA next to Ni o4(Ni o3)and negative SSTA next to Ni o3(Ni o4).Moreover,the variations of moisture transport from BOB and SC have important effects on persistent drought/flood in SC when the Ni o3.4 index is in the positive phase,while those from western North Pacific(WNP)-SC in winter and those from Philippine Sea(PHS)-SC and NC in spring primarily contribute to persistent drought/flood events in SC when the Ni o3.4 index is in the negative phase,and these stronger(weaker)moisture transports are observed in persistent flood(drought)during winter and spring regardless of the Ni o3.4 index.In conclusion,with the correlation between variations and distributions of Ni o3.4 SSTA and persistent drought/flood events in SC,moisture transport is responsible for the formation of precipitation anomalies.In addition,the moisture transport from SCS is most significantly correlated with persistent drought/flood events during winter and spring.展开更多
Based on monthly rainfall data from 80 stations of China for the period of January 1951—February 1985 analysed in terms of the maximum entropy spectrum and EEOF(extended empirical orthogonal function) techniques,the ...Based on monthly rainfall data from 80 stations of China for the period of January 1951—February 1985 analysed in terms of the maximum entropy spectrum and EEOF(extended empirical orthogonal function) techniques,the spatial and temporal features of quasi-biennial oscillation(QBO)in the rainfall are investigated in a detailed manner,with some results of interest acquired. Highly evident is the QBO in rainfall over China,especially the mid and lower reaches of the Changjiang River,the NE side of the Qinghai-Xizang Plateau,North China,the southern part of NE China,areas south of the Changjiang River and of the Nanling mountain region,and most of Xinjiang. The spatial wave described by the first and second eigenvectors of EEOF for eastern China is a type of wave travelling from NE to SW,indicating the cycle of patterns(in the south to north direction):dryness(D)- wetness(W)-dryness(D)→southern W-northern slight D→W-D-W→southern D-northern slight W→ D-W-D again,with the flooded region between the Changjiang and Huanghe Rivers for the D-W-D occurrence and with the Changjiang River as the division for the southern W-northern slight D happening.The third and fourth eigenvectors show a standing wave-like feature for the same eastern part,indicating the cycle of D-W- D→transition→W-D-W→transition→D-W-D,again,where the transition means the general weakening of drought and flooding and their subsequent reversal development. The amplitudes of the time coefficients of the first two eigenvectors are opposite in the trend of their changes to those of the next two and show a period of 10—14 years.展开更多
Filtering technique, extended empirical orthogonal function (EEOF), spectrum distribution function and correla- tion analysis have been employed to study the relationship between arctic ice cover (AIC) and monthly mea...Filtering technique, extended empirical orthogonal function (EEOF), spectrum distribution function and correla- tion analysis have been employed to study the relationship between arctic ice cover (AIC) and monthly mean tempera- ture and precipitation in China. The function of power spectrum density shows that not only a semi-annual and an an- nual oscillation but also a quasi-biennial oscillation can be found in AIC area index series, especially in June, September and November. During the period of analysis, it can also be found that there exists a good correlation between the El Nino events and the AIC area index. An analysis on the EEOF of AIC and the temperature over China exhibits some significant temporal-spatial patterns and a better time-lag interrelationship between them. The results from the correla- tion analysis indicate that the variation of AIC area has a significant influence on the temperature and precipitation in subsequent months over China. In addition, it experiences a quasi-biennial low-frequency oscillation and displays to certain extent some features of propagation.展开更多
基金National Key Basic Research Program of China(2014CB953902)National Natural Science Foundation of China(41175076,412111046)
文摘The interannual variability of winter and spring precipitation in South China(SC)and its relation to moisture transport are investigated by using the monthly precipitation data of NMIC,NCEP reanalysis datasets and NOAA ERSST analysis datasets from 1960 to 2008.The results show that winter and spring precipitation in SC is less than normal from the 1960s to the start of the 1970s and from the end of the 1990s to the present.Most of rainfall anomalies on the whole regional scale of SC is well in phase during winter and spring,and the frequency of persistent drought is higher than that of persistent flood.Seasonal variations of moisture transport differences of SC between persistent drought and flood events are observed:the differences in winter are characterized by moisture transport from Bay of Bangle(BOB)and South China Sea(SCS),while differences in spring are characterized by that from SCS and North China(NC).There are two types of Ni o3.4 sea surface temperature anomaly(SSTA)related to persistent winter and spring drought(flood)events in SC,which are positive SSTA next to Ni o4(Ni o3)and negative SSTA next to Ni o3(Ni o4).Moreover,the variations of moisture transport from BOB and SC have important effects on persistent drought/flood in SC when the Ni o3.4 index is in the positive phase,while those from western North Pacific(WNP)-SC in winter and those from Philippine Sea(PHS)-SC and NC in spring primarily contribute to persistent drought/flood events in SC when the Ni o3.4 index is in the negative phase,and these stronger(weaker)moisture transports are observed in persistent flood(drought)during winter and spring regardless of the Ni o3.4 index.In conclusion,with the correlation between variations and distributions of Ni o3.4 SSTA and persistent drought/flood events in SC,moisture transport is responsible for the formation of precipitation anomalies.In addition,the moisture transport from SCS is most significantly correlated with persistent drought/flood events during winter and spring.
基金This work is supported by National Natural Science Foundation of China.
文摘Based on monthly rainfall data from 80 stations of China for the period of January 1951—February 1985 analysed in terms of the maximum entropy spectrum and EEOF(extended empirical orthogonal function) techniques,the spatial and temporal features of quasi-biennial oscillation(QBO)in the rainfall are investigated in a detailed manner,with some results of interest acquired. Highly evident is the QBO in rainfall over China,especially the mid and lower reaches of the Changjiang River,the NE side of the Qinghai-Xizang Plateau,North China,the southern part of NE China,areas south of the Changjiang River and of the Nanling mountain region,and most of Xinjiang. The spatial wave described by the first and second eigenvectors of EEOF for eastern China is a type of wave travelling from NE to SW,indicating the cycle of patterns(in the south to north direction):dryness(D)- wetness(W)-dryness(D)→southern W-northern slight D→W-D-W→southern D-northern slight W→ D-W-D again,with the flooded region between the Changjiang and Huanghe Rivers for the D-W-D occurrence and with the Changjiang River as the division for the southern W-northern slight D happening.The third and fourth eigenvectors show a standing wave-like feature for the same eastern part,indicating the cycle of D-W- D→transition→W-D-W→transition→D-W-D,again,where the transition means the general weakening of drought and flooding and their subsequent reversal development. The amplitudes of the time coefficients of the first two eigenvectors are opposite in the trend of their changes to those of the next two and show a period of 10—14 years.
文摘Filtering technique, extended empirical orthogonal function (EEOF), spectrum distribution function and correla- tion analysis have been employed to study the relationship between arctic ice cover (AIC) and monthly mean tempera- ture and precipitation in China. The function of power spectrum density shows that not only a semi-annual and an an- nual oscillation but also a quasi-biennial oscillation can be found in AIC area index series, especially in June, September and November. During the period of analysis, it can also be found that there exists a good correlation between the El Nino events and the AIC area index. An analysis on the EEOF of AIC and the temperature over China exhibits some significant temporal-spatial patterns and a better time-lag interrelationship between them. The results from the correla- tion analysis indicate that the variation of AIC area has a significant influence on the temperature and precipitation in subsequent months over China. In addition, it experiences a quasi-biennial low-frequency oscillation and displays to certain extent some features of propagation.
