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In this study, the interdecadal increase in winter precipitation in northwest China (NWC) since the late 1980s and the associated moisture flux transport are investigated. The results show that an interdecadal change in moisture flux transport also occurred in the late 1980s, resulting in anomalous moisture transport convergence over NWC. The examination of boundary moisture transport shows enhanced incoming net moisture flux transport over NWC after the late 1980s. The zonal and meridional components both play a key role in the net moisture flux transport, with increased incoming transport from the western boundary dominated and followed by increased incoming transport from the southern boundary. The circulation responsible for the moisture flux transport anomalies is a Eurasian (EU)‐like teleconnection over mid‐to‐high latitudes of the Eurasian continent. The EU teleconnection pattern transformed from a positive phase to a negative phase in the late 1980s. The related anomalous cyclone over central Asia and the anomalous anticyclone over Japan result in westerly anomalies to the west of NWC and southeasterly anomalies to the east, respectively. Together, these anomalies enable an enhanced net gain of moisture transport and the anomalous moisture transport convergence over NWC. The enhanced moisture supply, strengthened upward movement and anomalous convergence result in an interdecadal increase in winter precipitation in NWC. In addition, the transition of the EU teleconnection is likely attributed to changes in the zonal mean wind. Sea surface temperature warming in the North Atlantic and northwestern Pacific regions also play a role in the change in the EU teleconnection pattern. [ABSTRACT FROM AUTHOR]

The present study investigates the features of the surface latent heat flux (LHF) anomalies and their related variables over the tropical Pacific during two types of El Niño-Southern Oscillation (ENSO) events and seeks a possible candidate for the main contributions to the LHF anomalies. During El Niño Modoki and canonical El Niño events, the LHFs show positive anomalies over the equatorial central Pacific and in the areas immediately south of the equatorial eastern Pacific. In addition, the largest magnitudes and widest ranges of positive LHF anomalies for both types of events occur during their mature stages rather than during their developing or decaying phases. Analyses show that the positive LHF anomalies associated with both events are largely affected by the positive sea-air humidity difference anomalies. However, the negative surface wind speed anomalies associated with the canonical El Niño events clearly contribute to the decreases in the positive LHF anomalies over the central Pacific and in the area immediately north of the equatorial eastern Pacific due to the presence of westerly and northerly anomalies, respectively. Moreover, over the equatorial central Pacific and in the area immediately south of the eastern Pacific, the LHF anomalies are mainly influenced by oceanic variables during both types of ENSO events, indicating an atmospheric response to oceanic forcing. In contrast, outside of the area spanning 10° north and south of the equator in the tropical Pacific and with the exception of the southeastern region, the LHF anomalies are greatly influenced by atmospheric variables, suggesting an oceanic response to atmospheric forcing. Distinct differences exist during the mature event phase, with oceanic forcing dominating the equatorial central Pacific during El Niño Modoki events and the area immediately south of the equatorial eastern Pacific during canonical El Niño events. In addition, both types of ENSO events suggest the increasing influence of oceanic forcing over the equatorial eastern Pacific during ENSO event evolutions. [ABSTRACT FROM AUTHOR]

ABSTRACT This study investigated the influence of the land-air temperature difference on spring rainfall over North China and its feedback mechanism by using station observations for the period 1951-2000 and the ERA-40 reanalysis for the period 1958-2002. The analysis identified a significant negative correlation between the land-air temperature difference and the spring rainfall over North China. The analysis results suggested that the sinking motion and northeasterly anomalies were dominated over North China. These anomalous northeasterly winds substantially weakened the amount of moisture supplied to North China and are helpful for a decrease in the humidity over North China. Moreover, the decrease in sea level pressure was caused by an increase in surface air temperature. The North China was located to the west of Low system where divergence and sinking motion were favoured. The results also suggested that the positive sensible heat flux anomalies and negative latent heat flux anomalies over North China were induced by an increase in the land-air temperature difference. The increase in surface downward solar radiation association with a decrease in low clouds may cause an increase in surface air temperature and decrease in relative humidity, which in turn contributed to a decrease in spring rainfall over North China. These results suggested that there was a strong negative feedback mechanism between the temperature difference and rainfall. [ABSTRACT FROM AUTHOR]

ABSTRACT Winter precipitation in Northwest China experienced an obvious interdecadal increase around 1987. Consistent increase in winter precipitation occurred in Middle Asia. This study investigates associated changes in atmospheric circulation and sea surface temperature ( SST). Analyses show that winter water vapour flux and atmospheric circulation over the North Atlantic Ocean and Eurasia and SST in the North Atlantic Ocean were very different before and after 1987. During 1987-2008, a significant enhancement of tropospheric moisture convergence and ascending motion was observed over Northwest China and Middle Asia. This contributed to the increase of winter precipitation in Northwest China and Middle Asia. The wind difference field before and after 1987 features cyclones over Middle Asia and North Atlantic Ocean and anticyclones over East Asia and southern Europe-northern Africa, signifying an obvious change in the Eurasian ( EU) teleconnection pattern over middle latitudes of Eurasia. The results indicate that the Middle Asia and Northwest China were under the influence of enhanced westerlies from the North Atlantic Ocean that strengthened the water vapour transport to Middle Asia and Northwest China after 1987. Moreover, the interdecadal variability in the EU pattern is associated with the SST increase in the North Atlantic Ocean. Thus, the North Atlantic SST change is likely an important reason for the winter precipitation increase in Middle Asia and Northwest China. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. The presentation of Eq. 4 and inline equations in the succeeding paragraph were incorrect. [ABSTRACT FROM AUTHOR]