Pacific Decadal Oscillation (PDO) is a long-term ENSO-like variability of theNorth Pacific. It is the first principal component of EOF of the North Pacific SST. ENSO is thestrongest signal of annular change of global ...Pacific Decadal Oscillation (PDO) is a long-term ENSO-like variability of theNorth Pacific. It is the first principal component of EOF of the North Pacific SST. ENSO is thestrongest signal of annular change of global climate system. Empirical Mode Decomposition (EMD)method is applied to two types of indices. One type of index is the Pacific Decadal Oscillation(PDO) index that represents a long-term ENSO-like variability of the North Pacific. The other typeof indices such as Southern Oscillation (SO) index, Ninol+2 SST, Nino3 SST, Nino4 SST and Nino3.4SST represents ENSO. The relationship between two types of indices shows the temporalcharacteristics and relationships between the two phenomena. It is found that, for PDO, the goodcorrelations with ENSO only exist on the quasi-2-7-yr timescales and decadal and multi-decadaltimescales, suggesting that a close relationship between PDO and ENSO only exists among some specialintrinsic mode functions at lower frequency band.展开更多
Complex topography,special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China(ESWC).However,the contributions,influencing fa...Complex topography,special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China(ESWC).However,the contributions,influencing factors and mechanisms of remote and local evaporation remain to be further investigated.Using clustering analysis and Hybrid Single-Particle Lagrangian Integrated Trajectory version 5 model,we analyze the contributions of remote moisture transport and local evaporation to summer precipitation in the ESWC and their causes.There are mainly five remote moisture channels in the ESWC,namely the Arabian Sea channel,Bay of Bengal channel,western Pacific channel,Northwest channel 1 and Northwest channel 2.Among the five channels,the western Pacific channel has the largest number of trajectories,while the Bay of Bengal channel has the largest contribution rate of specific humidity(33.33%)and moisture flux(33.14%).The amount of regional average precipitation is close to that of the precipitation caused by remote moisture transport,and both are considerably greater than the rainfall amount caused by local evaporation.However,on interannual time scales,precipitation recirculation rates are negatively correlated to regional average precipitation and precipitation caused by remote moisture transport but are consistent with that caused by local evaporation.An apparent"+-+"wave train can be found on the height anomaly field in East Asia,and the sea surface temperature anomalies are positive in the equatorial Middle-East Pacific,the South China Sea,the Bay of Bengal and the Arabian Sea.These phenomena cause southwest-northeast moisture transport with strong updrafts,thereby resulting in more precipitation in the ESWC.展开更多
基金This work is jointly supported by the National Natural Science Foundation of China under Grant Nos. 40233028, 40075017.
文摘Pacific Decadal Oscillation (PDO) is a long-term ENSO-like variability of theNorth Pacific. It is the first principal component of EOF of the North Pacific SST. ENSO is thestrongest signal of annular change of global climate system. Empirical Mode Decomposition (EMD)method is applied to two types of indices. One type of index is the Pacific Decadal Oscillation(PDO) index that represents a long-term ENSO-like variability of the North Pacific. The other typeof indices such as Southern Oscillation (SO) index, Ninol+2 SST, Nino3 SST, Nino4 SST and Nino3.4SST represents ENSO. The relationship between two types of indices shows the temporalcharacteristics and relationships between the two phenomena. It is found that, for PDO, the goodcorrelations with ENSO only exist on the quasi-2-7-yr timescales and decadal and multi-decadaltimescales, suggesting that a close relationship between PDO and ENSO only exists among some specialintrinsic mode functions at lower frequency band.
基金National Natural Science Foundation of China(41875111)Special program for innovation and development of China Meteorological Administration(CXFZ2022J031,CXFZ2021J018)National Natural Science Foundation of China(40975058)。
文摘Complex topography,special geographical location and sea-land-air interactions lead to high interannual variability of summer precipitation in the east of Southwest China(ESWC).However,the contributions,influencing factors and mechanisms of remote and local evaporation remain to be further investigated.Using clustering analysis and Hybrid Single-Particle Lagrangian Integrated Trajectory version 5 model,we analyze the contributions of remote moisture transport and local evaporation to summer precipitation in the ESWC and their causes.There are mainly five remote moisture channels in the ESWC,namely the Arabian Sea channel,Bay of Bengal channel,western Pacific channel,Northwest channel 1 and Northwest channel 2.Among the five channels,the western Pacific channel has the largest number of trajectories,while the Bay of Bengal channel has the largest contribution rate of specific humidity(33.33%)and moisture flux(33.14%).The amount of regional average precipitation is close to that of the precipitation caused by remote moisture transport,and both are considerably greater than the rainfall amount caused by local evaporation.However,on interannual time scales,precipitation recirculation rates are negatively correlated to regional average precipitation and precipitation caused by remote moisture transport but are consistent with that caused by local evaporation.An apparent"+-+"wave train can be found on the height anomaly field in East Asia,and the sea surface temperature anomalies are positive in the equatorial Middle-East Pacific,the South China Sea,the Bay of Bengal and the Arabian Sea.These phenomena cause southwest-northeast moisture transport with strong updrafts,thereby resulting in more precipitation in the ESWC.
