The southeastern Tibetan Plateau is one of the predominant summer rainfall regions in the world and is also the crucial water vapor channel of the Asian summer monsoon. The rainfall variability in the region influences not only the local communities but also downstream communities in East Asia. However, previous studies have exhibited large rainfall biases in this region in state‐of‐the‐art climate models. Understanding the observed rainfall variability provides an opportunity to identify the origin of model biases and to lay a foundation for improving model performance. In this study, the interannual variability of the summer precipitation (May–September) over the southeastern Tibetan Plateau was investigated based on National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis monthly mean data from 1979 to 2010. The associated atmospheric circulation anomalies of the southeastern Tibetan Plateau summer precipitation (SET_PR) display a North Atlantic Ocean‐Europe‐Asia teleconnection pattern, indicating a possible role of the Atlantic climate in the SET_PR. Further studies have revealed that the Atlantic sea surface temperature (SST) anomalies have the greatest influence on the SET_PR via the Rossby wave response, whereas the SST anomalies in the Indo‐Pacific have less of an influence on the SET_PR because their main impacts are confined to the western North Pacific subtropical high and the monsoonal circulation there. This paper also documents the detailed spatial pattern of the atmospheric circulation anomalies associated with the SET_PR and Atlantic SST year‐to‐year variability.
27 August 2020 in Journal of Geophysical Research: Atmospheres
This paper focuses on the interdecadal variation in drought in Northeast China (NEC) in recent decades. Two dry and wet periods have occurred in the past 61 years (1950–2010). The mechanism underlying the interdecadal variation in drought in NEC is further analyzed; the results indicate that the direct cause is the interdecadal change of the Okhotsk High (OH). A strong (weak) OH is conducive (detrimental) to the convergence of cold air transported by northeast cold vortex and water vapor from the east of NEC, eventually leading to an increase (decrease) in precipitation. Furthermore, we seek to understand why OH displays such an interdecadal variation. The interdecadal increases and decreases in sea ice in the Barents Sea and the Kara Sea explain most of the interdecadal change of the OH. When more sea ice is present in this area, more energy is transferred eastward from the sea ice area to Northeast Asia, weakening the OH; in contrast, less sea ice strengthens the OH. Sensitivity simulations by Community Atmosphere Model, version 4 (CAM4) using sea ice forcing in the Barents Sea and the Kara Sea yield similar results to the observed data, further confirming our conclusion. The results of this paper provide a new understanding of the interdecadal variation in drought in NEC, and it may help to improve our ability to predict drought and provide early warning in the future.
Twenty‐one climate models from Coupled Model Intercomparison Project Phase 3 (CMIP3) and thirty‐one models from the project's Phase 5 (CMIP5) were used to evaluate model reproducibility in assessing interannual variability of summer precipitation in Pan‐Asian monsoon region. The results show that both the multi‐model ensemble means of the best eight models and of the thirty‐one CMIP5 models are more skilful than those of the CMIP3 models in simulating the climatological pattern and the dominant mode of summer precipitation in Pan‐Asian monsoon region. CMIP5 models show improved skill in representing the main characteristic of the first mode of summer precipitation in Pan‐Asian monsoon region, which is a meridional tripole pattern from north to south occurring east of the 80°E region. That is, owing to the improved El Niño–Southern Oscillation (ENSO) pattern and the relationship between Antarctic oscillation in the southern Pacific Ocean (AAOSP) and ENSO, the first dominant mode of summer precipitation in Pan‐Asian monsoon region are captured by CMIP5 models, which indicates that these models are more skilful in simulating the air–sea interaction of the Southern Hemisphere.
7 March 2018 in International Journal of Climatology
Based on the Twentieth Century Reanalysis version 2 datasets (1871–2010), this article first analyzes the relationships of the Arctic Oscillation (AO) and the El Niño‐Southern Oscillation (ENSO) with the East Asian winter monsoon (EAWM) and further investigates the changes in the relationships between the ENSO (AO) and EAWM before and after removing the AO (ENSO) signal. As revealed by previous studies, an interdecadal oscillating relationship is found between the ENSO and EAWM. This oscillation disappears when the AO signal is removed; however, the ENSO–EAWM relationship has exhibited a stable and significant negative correlation over the past 140 years. In contrast, the oscillating relationship (with a period of approximately 60 years) between the AO and EAWM shows little differences when the ENSO signal is removed. Further analysis reveals the main reasons for the strengthening of the ENSO–EAWM relationship by removing the AO signal. The results show that after removing the AO signal, the ENSO‐induced anomalous sinking branch of the Walker circulation over the western Pacific shifts northwestward, and the ENSO‐related anomalous anticyclone in the northern part of the western Pacific strengthens. Such circulation anomalies are conducive to the establishment of the East Asia–North Pacific teleconnection, which is favourable for the ENSO–EAWM relationship. The above results reveal that there is an interdecadal oscillation in the AO–EAWM relationship and the ENSO–EAWM relationship may be relatively stable, the interdecadal oscillation only occurs under the influence of the AO. These results may improve the use of ENSO for predicting the EAWM on seasonal time scale in the future.