scholarly journals Influence of the Tibetan Plateau snow cover on East Asian winter upper-level jet streams at daily time scale

2018 ◽  
Author(s):  
Weidong Guo ◽  
Wenkai Li ◽  
Yongkang Xue
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Time Scale ◽  
East Asian ◽  
The Tibetan Plateau ◽  
Jet Streams ◽  
Upper Level ◽  
Upper Level Jet ◽  
Tibetan Plateau Snow Cover ◽  
Daily Time

scholarly journals Decreasing Influence of Summer Snow Cover Over the Western Tibetan Plateau on East Asian Precipitation Under Global Warming

2021 ◽  
Vol 9 ◽  
Author(s):  
Zhibiao Wang ◽  
Renguang Wu ◽  
Zhang Chen ◽  
Lihua Zhu ◽  
Kai Yang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
East Asian ◽  
Summer Precipitation ◽  
Northern China ◽  
The Tibetan Plateau ◽  
Western Tibetan Plateau ◽  
Asian Summer ◽  
Tibetan Plateau Snow Cover ◽  
East Asian Summer Precipitation

In recent years, some studies emphasized the influence of western Tibetan Plateau summer snow on the East Asian summer precipitation. With the temperature rise in the past decades, the snow cover over the western Tibetan Plateau in summer has significantly decreased. This raises the question whether the impact of the Tibetan Plateau snow has changed. The present study identifies a prominent change in the influence of the western Tibetan Plateau snow cover on the East Asian summer precipitation. Before the early 2000’s, positive precipitation anomalies extend from the southeastern Tibetan Plateau through the Yangtze River to Japan and Korea and negative anomalies cover southeast China corresponding to more Tibetan Plateau snow cover. After the early 2000’s, with the reduction of snow cover variability, below-normal and above-normal summer precipitation occurs over northern China-Mongolia and northeast Asia, respectively, corresponding to more Tibetan Plateau snow cover. The change in the influence of the Tibetan Plateau snow on the East Asian summer precipitation is associated with an obvious change in the atmospheric circulation anomaly pattern. Before the early 2000’s, the wind anomalies display a south-north contrast pattern with anomalous convergence along the Yangtze River. After the early 2000’s, an anomalous cyclone occupies Northeast China with anomalous southerlies and northerlies over northeast Asia and northern China, respectively. The Tibetan Plateau snow cover variation after the early 2000’s is associated with the northeast Indian summer precipitation. The model experiments confirm that the weakened influence of summer western Tibetan Plateau snow cover on the East Asian atmospheric circulation and precipitation with the reduced snow cover anomalies.

scholarly journals Modulation of the Tibetan Plateau Snow Cover on the ENSO Teleconnections: From the East Asian Summer Monsoon Perspective

2012 ◽  
Vol 25 (7) ◽  
pp. 2481-2489 ◽  
Author(s):  
Zhiwei Wu ◽  
Jianping Li ◽  
Zhihong Jiang ◽  
Tingting Ma
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
The Tibetan Plateau ◽  
Eastern Asia ◽  
Enso Teleconnections ◽  
Asian Summer ◽  
Tibetan Plateau Snow Cover

Abstract The East Asian summer monsoon (EASM) may exhibit rather large variability between years characterized by the same ENSO phase. Such inconsistency reduces the EASM predictability based on ENSO. Results in this study show that the Tibetan Plateau snow cover (TPSC) exerts a modulating effect on ENSO teleconnections and ENSO significantly correlates with the EASM only during the reduced TPSC summers. Three-dimensional circulation structures are examined to manifest that the typical ENSO signals in reduced TPSC summers tend to be stronger than in excessive TPSC summers. Numerical and theoretical evidences indicate that the anomalously reduced TPSC can force positive geopotential height anomalies at the upper troposphere and weaken the jet streams across eastern Asia and northwestern Pacific. Governed by such basic state zonal flows, the extratropical Rossby wave response to the ENSO forcing usually has a larger amplitude and pronounced westward development. In such case, ENSO extends its influences to eastern Asia and enhances its connection with the EASM.

Rapid response of the East Asian trough to Tibetan Plateau snow cover

2020 ◽  
Vol 41 (1) ◽  
pp. 251-261 ◽  
Author(s):  
Wenkai Li ◽  
Bo Qiu ◽  
Weidong Guo ◽  
Pang‐chi Hsu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
East Asian ◽  
Rapid Response ◽  
East Asian Trough ◽  
Tibetan Plateau Snow Cover

Historical change of winter Tibetan Plateau snow cover and its controlling factors

2021 ◽  
Author(s):  
Shixue Li ◽  
Tomonori Sato ◽  
Tetsu Nakamura
Keyword(s):  
Global Warming ◽  
Tibetan Plateau ◽  
Snow Cover ◽  
Internal Variability ◽  
Controlling Factors ◽  
Historical Change ◽  
The Tibetan Plateau ◽  
Vapor Flux ◽  
The Impact ◽  
Tibetan Plateau Snow Cover

<p>This study investigates the controlling factors of the interannual variability of Tibetan Plateau snow cover (TPSC) in winter. Since snow observation in Tibetan Plateau is limited in space and time, high-resolution multi-satellite data for TPSC were analyzed during 1982-2016. In addition, a large ensemble AGCM experiment from d4PDF (hereafter, HIST), driven by observed SST and anthropogenic forcings were analyzed during 1951-2010 to compare the contributions arising from internal variability and external forcings including the change in greenhouse gases (GHGs) concentration on TPSC variation. In this study TPSC fraction (hereafter, TPSCF) is defined as the percentage of the snow-covered area over the Tibetan Plateau. For both observation and HIST, high and low TPSCF years determined by the standardized January-March TPSCF were analyzed. The range of interannual TPSCF variation (i.e., TPSCF difference between high and low TPSCF years) is about 11% in both observation and the model, suggesting the AGCM well reproduced the TPSCF variability in the interannual timescale. </p><p>We found that high TPSCF is linked to a positive-AO-like pattern. The interannual variation of the observed AO index and TPSCF are significantly correlated. In d4PDF high TPSCF more likely appears with a higher (positive) AO index and vice versa. In high TPSCF years, the subtropical jet is strengthened, which significantly enhances zonal water vapor flux reaching the plateau supporting more precipitation. Another interesting result is a disagreement for ENSO’s contribution to TPSC appears between observation and HIST. However, several members in HIST show a feature close to the observation, in which TPSCF anomalies are not sensitive to the El Niño/La Niña events. Thus, this weak linkage between ENSO and TPSCF is more likely due to the limited cases of observations rather than the model bias. Finally, by comparing HIST and non-warming experiments (NAT), we found historical global warming has decreased the snow-to-rain ratio over TP. Nonetheless, increased precipitation compensates for it. As a result, the impact of historical global warming on TPSCF could be considered negligibly weak.</p>

scholarly journals Influence of Tibetan Plateau snow cover on East Asian atmospheric circulation at medium-range time scales

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Wenkai Li ◽  
Weidong Guo ◽  
Bo Qiu ◽  
Yongkang Xue ◽  
Pang-Chi Hsu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Atmospheric Circulation ◽  
Time Scales ◽  
East Asian ◽  
Medium Range ◽  
Tibetan Plateau Snow Cover

scholarly journals Systematic bias of Tibetan Plateau snow cover in subseasonal-to-seasonal models

2020 ◽  
Author(s):  
Shuzhen Hu ◽  
Wenkai Li
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Air Temperature ◽  
Lead Time ◽  
Surface Air Temperature ◽  
The Tibetan Plateau ◽  
Systematic Bias ◽  
Forecast Lead Time ◽  
Systematic Biases ◽  
Tibetan Plateau Snow Cover

Abstract. Accurate subseasonal-to-seasonal (S2S) atmospheric forecasts and hydrological forecasts have considerable socioeconomic value. This study conducts a multimodel comparison of the Tibetan Plateau snow cover (TPSC) prediction skill using three models (ECMWF, NCEP and CMA) selected from the S2S project database to understand their performance in capturing TPSC variability. S2S models can skilfully forecast TPSC within a lead time of 2 weeks but show limited skill beyond 3 weeks. Compared with the observational snow cover analysis, all three models tend to overestimate the area of TPSC, especially during winter. Another remarkable issue regarding the TPSC forecast is the increasing TPSC with forecast lead time, which further increases the systematic positive biases of TPSC in the S2S models at longer forecast lead times. The underestimation of TPSC dissipation induces an increase in TPSC with forecast lead time in the models. Such systematic biases of TPSC influence the forecasted surface air temperature in the S2S models. The surface air temperature over the Tibetan Plateau becomes colder with increasing forecast lead time in the S2S models.

An interdecadal change in the influence of ENSO on the spring Tibetan Plateau snow cover variability in the early 2000s

2021 ◽  
pp. 1
Author(s):  
Zhibiao Wang ◽  
Renguang Wu ◽  
Song Yang ◽  
Mengmeng Lu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Southern Oscillation ◽  
Interdecadal Change ◽  
The Tibetan Plateau ◽  
The Relationship ◽  
Tibetan Plateau Snow Cover ◽  
Sst Anomalies

AbstractEl Niño–Southern Oscillation (ENSO) and the Tibetan Plateau snow cover are important factors in interannual climate variability. The relationship between ENSO and the Tibetan Plateau snow variation is still an issue unresolved. While some studies suggested that ENSO is a key factor of changes in snow cover over the Tibetan Plateau, other studies noted independence between the two. The present study revealed a prominent interdecadal change in the relationship between ENSO and the spring Tibetan Plateau snow cover variation in the early 2000s. There is a significant positive correlation between ENSO and the spring Tibetan Plateau snow cover variation in the period 1988-2003, but an obvious negative relationship is detected in the period 2004-2019. The interdecadal change in the ENSO-snow relationship is related to the distinct pathway of ENSO influence on the spring Tibetan Plateau snow cover variation during the two periods. In the period 1988-2003, ENSO induces anomalous convection over the tropical western North Pacific that in turn cause atmospheric circulation and moisture anomalies over the Tibetan Plateau. The resultant winter snow anomalies over the central-eastern Tibetan Plateau persist to the following spring. In the period 2004-2019, ENSO induces North Atlantic sea surface temperature (SST) anomalies in winter that are maintained to the following spring. The North Atlantic SST anomalies then stimulate the atmospheric circulation anomalies extending to the Tibetan Plateau that induce snow cover anomalies there in spring. The different processes of ENSO influence lead to opposite anomalies of spring snow cover over the Tibetan Plateau in the two periods.

scholarly journals Systematic bias of Tibetan Plateau snow cover in subseasonal-to-seasonal models

2020 ◽  
Vol 14 (10) ◽  
pp. 3565-3579
Author(s):  
Wenkai Li ◽  
Shuzhen Hu ◽  
Pang-Chi Hsu ◽  
Weidong Guo ◽  
Jiangfeng Wei
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Air Temperature ◽  
Lead Time ◽  
Surface Air Temperature ◽  
Model Integration ◽  
The Tibetan Plateau ◽  
Systematic Bias ◽  
Forecast Lead Time ◽  
Tibetan Plateau Snow Cover

Abstract. Accurate subseasonal-to-seasonal (S2S) atmospheric forecasts and hydrological forecasts have considerable socioeconomic value. This study conducts a multimodel comparison of the Tibetan Plateau snow cover (TPSC) prediction skill using three models (ECMWF, NCEP and CMA) selected from the S2S project database to understand their performance in capturing TPSC variability during wintertime. S2S models can skillfully forecast TPSC within a lead time of 2 weeks but show limited skill beyond 3 weeks. Compared with the observational snow cover analysis, all three models tend to overestimate the area of TPSC. Another remarkable issue regarding the TPSC forecast is the increasing TPSC with forecast lead time, which further increases the systematic positive biases of TPSC in the S2S models at longer forecast lead times. All three S2S models consistently exaggerate the precipitation over the Tibetan Plateau. The exaggeration of precipitation is prominent and always exists throughout the model integration. Systematic bias of TPSC therefore occurs and accumulates with the model integration time. Such systematic biases of TPSC influence the forecasted surface air temperature in the S2S models. The surface air temperature over the Tibetan Plateau becomes colder with increasing forecast lead time in the S2S models. Numerical experiments further confirm the causality.

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