scholarly journals Southern Hemisphere Origins for Interannual Variations of Snow Cover over the Western Tibetan Plateau in Boreal Summer

2018 ◽  
Vol 31 (19) ◽  
pp. 7701-7718 ◽  
Author(s):  
Juan Dou ◽  
Zhiwei Wu
Keyword(s):  
Indian Ocean ◽  
Tibetan Plateau ◽  
Snow Cover ◽  
Southern Hemisphere ◽  
Temperature Anomaly ◽  
Western Indian Ocean ◽  
Boreal Summer ◽  
The Tibetan Plateau ◽  
Interannual Variations ◽  
Wave Ray

The climate response to the Tibetan Plateau (TP) snow cover (TPSC) has been receiving extensive concern. However, relatively few studies have been devoted to revealing the potential factors that can contribute to the TPSC interannual variability, especially during boreal summer. This study finds that the May Southern Hemisphere (SH) annular mode (SAM), the dominating mode of atmospheric circulation variability in the SH extratropics, exhibits a significant positive relationship with the interannual variations in western TPSC during boreal summer. Observational analysis and numerical experiments manifest that the signal of the May SAM can be “prolonged” by a meridional Indian Ocean tripole (IOT) sea surface temperature anomaly (SSTA) via atmosphere–ocean interaction. The IOT SSTA pattern persists into the following summer and excites anomalous local-scale zonal–vertical circulation. Subsequently, a tropical dipole rainfall (TDR) mode is induced with precipitation anomalies between the tropical western Indian Ocean and the eastern Indian Ocean–Maritime Continent. Rossby wave ray tracing diagnosis reveals that the wave energies, generated by the latent heat release of the TDR mode, can propagate northward into the western TP. As a response, abnormal cyclone (or anticyclone) and upward (or downward) movement are triggered over the western TP, providing favorable dynamical conditions for more (or less) TPSC. Moreover, the strong May SAM is usually followed by a cold air temperature anomaly over the western TP in summer, which is unfavorable for snow-cover melting, and vice versa. In brief, the IOT SSTA plays an “ocean bridge” role and the TDR mode plays an “atmosphere bridge” role in the process of the May SAM impacting the following summer TPSC variability. The results may provide new insight into the cross-equatorial propagation of the SAM influence.

scholarly journals Response of convective systems to the orbital forcing of the last interglacial in a global nonhydrostatic atmospheric model with and without a convective parameterization

2022 ◽  
Author(s):  
Minoru Chikira ◽  
Yohei Yamada ◽  
Ayako Abe-Ouchi ◽  
Masaki Satoh
Keyword(s):  
Indian Ocean ◽  
Tibetan Plateau ◽  
Tropical Cyclones ◽  
Atmospheric Model ◽  
Boreal Summer ◽  
The Tibetan Plateau ◽  
Last Interglacial ◽  
The South ◽  
Orbital Parameters ◽  
Convective Parameterization

AbstractNonhydrostatic Icosahedral Atmospheric Model (NICAM) coupled with a slab ocean model was applied to a paleoclimate research for the first time. The model was run at a horizontal resolution of 56 km with and without a convective parameterization, given the orbital parameters of the last interglacial (127,000 years before present). The simulated climatological mean-states are qualitatively similar to those in previous studies reinforcing their robustness, however, the resolution of this model enables to represent the narrow precipitation band along the southern edge of the Tibetan Plateau. A particular focus was given to convectively coupled disturbances in our analysis. The simulated results show a greater signal of the Madden–Julian Oscillation and weakening of the moist Kelvin waves. Although the model's representation of the boreal summer intraseasonal oscillation in the present-day simulations is not satisfactory, a significant enhancement of its signal is found in the counterpart of the last interglacial. The density of the tropical cyclones decreases over the western north Pacific, north Atlantic and increases over the south Indian Ocean and south Atlantic. The model's performance is generally better when the convective parameterization is used, but the tropical cyclones are better represented without the convective parameterization. Additional simulations using the low-resolution topography reveals that the better representation of the Tibetan Plateau enhances the boreal summer Asian monsoon and its impact is similar and comparable to that of the orbital parameters over the south Asia and the Indian Ocean.

scholarly journals Response of Convective Systems to the Orbital Forcing of the Last Interglacial in a Global Nonhydrostatic Atmospheric Model With and Without a Convective Parameterization

2021 ◽  
Author(s):  
Minoru Chikira ◽  
Yohei Yamada ◽  
Ayako Abe-Ouchi ◽  
Masaki Satoh
Keyword(s):  
Indian Ocean ◽  
Tibetan Plateau ◽  
Tropical Cyclones ◽  
Atmospheric Model ◽  
Boreal Summer ◽  
The Tibetan Plateau ◽  
Last Interglacial ◽  
The South ◽  
Orbital Parameters ◽  
Convective Parameterization

Abstract Nonhydrostatic Icosahedral Atmospheric Model (NICAM) coupled with a slab ocean model was applied to a paleoclimate research for the first time. The model was run at a horizontal resolution of 56km with and without a convective parameterization, given the orbital parameters of the last interglacial (127,000 years before present). The simulated climatological mean-states are qualitatively similar to those in previous studies reinforcing their robustness, however, the resolution of this model enables to represent the narrow precipitation band along the southern edge of the Tibetan Plateau. A particular focus was given to convectively coupled disturbances in our analysis. The simulated results show a greater signal of the Madden-Julian Oscillation and weakening of the moist Kelvin waves. Although the model's representation of the boreal summer intraseasonal oscillation in the present-day simulations is not satisfactory, a significant enhancement of its signal is found in the counterpart of the last interglacial. The density of the tropical cyclones decreases over the western north Pacific, north Atlantic and increases over the south Indian ocean and south Atlantic. The model's performance is generally better when the convective parameterization is used, but the tropical cyclones are better represented without the convective parameterization. Additional simulations using the low-resolution topography reveals that the better representation of the Tibetan Plateau enhances the boreal summer Asian monsoon and its impact is similar and comparable to that of the orbital parameters over the south Asia and the Indian ocean.

scholarly journals Spatio-Temporal Variation Characteristics of Snow Depth and Snow Cover Days over the Tibetan Plateau

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 307
Author(s):  
Chi Zhang ◽  
Naixia Mou ◽  
Jiqiang Niu ◽  
Lingxian Zhang ◽  
Feng Liu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Snow Depth ◽  
Feedback Effect ◽  
Effect Of Temperature ◽  
The Tibetan Plateau ◽  
Reanalysis Dataset ◽  
Spatio Temporal ◽  
The Impact ◽  
Main Factor

Changes in snow cover over the Tibetan Plateau (TP) have a significant impact on agriculture, hydrology, and ecological environment of surrounding areas. This study investigates the spatio-temporal pattern of snow depth (SD) and snow cover days (SCD), as well as the impact of temperature and precipitation on snow cover over TP from 1979 to 2018 by using the ERA5 reanalysis dataset, and uses the Mann–Kendall test for significance. The results indicate that (1) the average annual SD and SCD in the southern and western edge areas of TP are relatively high, reaching 10 cm and 120 d or more, respectively. (2) In the past 40 years, SD (s = 0.04 cm decade−1, p = 0.81) and SCD (s = −2.3 d decade−1, p = 0.10) over TP did not change significantly. (3) The positive feedback effect of precipitation is the main factor affecting SD, while the negative feedback effect of temperature is the main factor affecting SCD. This study improves the understanding of snow cover change and is conducive to the further study of climate change on TP.

Assessment of MODIS-Based Fractional Snow Cover Products Over the Tibetan Plateau

2019 ◽  
Vol 12 (2) ◽  
pp. 533-548 ◽  
Author(s):  
Shirui Hao ◽  
Lingmei Jiang ◽  
Jiancheng Shi ◽  
Gongxue Wang ◽  
Xiaojing Liu
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
The Tibetan Plateau ◽  
Fractional Snow Cover

scholarly journals IMPACT OF TIBETAN PLATEAU SNOW COVER ON ABRUPT INTERDECADAL PRECIPITATION CHANGE OVER THE INDOCHINA PENINSULA IN THE MID-1990S

2019 ◽  
Vol XLII-3/W9 ◽  
pp. 57-62
Author(s):  
Y. Ha ◽  
Y. M. Zhu ◽  
Y. J. Hu ◽  
Z. Zhong
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Summer Precipitation ◽  
Tropical Indian Ocean ◽  
Western Pacific Subtropical High ◽  
Precipitation Change ◽  
Interdecadal Change ◽  
Northwestern Pacific ◽  
The Tibetan Plateau ◽  
Indochina Peninsula

Abstract. Abrupt interdecadal changes in summer precipitation (May – September) over the Indochina Peninsula in the past 40 years have been investigated based on the NCEP-NCAR reanalysis product over 1979–2013 and multiple precipitation datasets. The mechanism for the abrupt change is explored. Results indicate that an abrupt interdecadal change in summer precipitation over the Indochina Peninsula occurred in the middle 1990s, and the annual mean summer precipitation during 1994–2002 increased by about 10% compared to that during 1982–1993. The most significant precipitation change occurred in the central and northern peninsula. Further analysis reveals that the interdecadal decrease in snow cover over the Tibetan Plateau in the winter and spring contributed to the summer precipitation increase over the Indochina Peninsula. The decrease in snow cover over the Tibetan Plateau actually increased the thermal contrast between the Tibetan Plateau and the tropical Indian Ocean-northwestern Pacific, leading to intensified summer monsoon over the northwestern Pacific and the South China Sea. As a result, westerly anomalies occurred from the Bay of Bengal to the northwestern Pacific, while anomalous cyclonic circulation prevailed in the upper levels above East Asia. Correspondingly, the western Pacific subtropical high weakened and shifted eastward. Under the joint effects of the above circulation patterns, the atmosphere became wetter in the Indochina Peninsula and summer precipitation increased. Results of the present study provide a theoretical basis for the prediction of long-term summer precipitation change in the Indochina Peninsula.

scholarly journals Fractional Snow-Cover Mapping Based on MODIS and UAV Data over the Tibetan Plateau

2017 ◽  
Vol 9 (12) ◽  
pp. 1332 ◽  
Author(s):  
Hui Liang ◽  
Xiaodong Huang ◽  
Yanhua Sun ◽  
Yunlong Wang ◽  
Tiangang Liang
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
The Tibetan Plateau ◽  
Fractional Snow Cover
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