Interrelation among climate factors, snow cover, grassland vegetation, and lake in the Nam Co basin of the Tibetan Plateau

Abstract. The Tibetan Plateau and the adjacent high mountain regions of the Himalayas play an important role in the global climate dynamic through its impact on the Asian monsoon system, which in turn is impacting the water resources of this extremely vulnerable region. To provide further knowledge about the changing impact of rainfall patterns, spatial and temporal variability of snow cover contribution, amount of snow and ice melt runoff, evapotranspiration as well as dynamics of wetlands and permafrost water balance studies are required. This is of particular importance in terms of global climate change because of a severe gap in the knowledge of the short, mid and long term implications on the hydrological system. This study concentrates on the macroscale catchment of the lake Nam Co, located at 4718 m a.s.l. at the foot of the Nyainqentanglha Mountains in central Tibet (30° N, 90° E). The water balance of the Nam Co basin is dominated by semi-arid climate, snow and ice melt runoff and high evaporation rates due to the high radiation input and the low air humidity. The observed temperature rise, glacier retreat, permafrost decay and lake level increase indicate significant system changes and the high sensitivity of the Tibetan Plateau on global warming. The development of a suitable water balance model and its preliminary application was the main objective of this study. The development was done with the Jena Adaptable Modelling System JAMS along with existing scientific process components of the J2000 module library which were partly further developed to reflect the specific conditions of the high elevation Nam Co basin. The preliminary modelling exercise based on gridded data from a downscaled ECHAM5 data set provided reasonable estimates about the important hydrological water balance components of the Nam Co basin. With the modelling results the observed lake level rise could be reproduced and it could be shown that the runoff from the glaciered areas seems to be the most important component to explain the increasing amount of lake water.

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

Water ◽

10.3390/w13030307 ◽

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.

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Surface ozone at Nam Co (4730 m a.s.l.) in the inland Tibetan Plateau: variation, synthesis comparison and regional representativeness

10.5194/acp-2017-175 ◽

2017 ◽

Cited By ~ 1

Author(s):

Xiufeng Yin ◽

Shichang Kang ◽

Benjamin de Foy ◽

Zhiyuan Cong ◽

Jiali Luo ◽

...

Keyword(s):

Tibetan Plateau ◽

Surface Ozone ◽

Early Morning ◽

Photochemical Reactions ◽

Transport Processes ◽

The Tibetan Plateau ◽

Nam Co ◽

Mixing Ratios ◽

Northern Tibetan Plateau ◽

Ozone Levels

Abstract. Ozone is an important pollutant and greenhouse gas, and tropospheric ozone variations are generally associated with both natural and anthropogenic processes. As one of the most pristine and inaccessible regions in the world, the Tibetan Plateau has been considered as an ideal region for studying processes of the background atmosphere. Due to the vast area of the Tibetan Plateau, sites in the southern, northern and central regions exhibit different patterns of variation in surface ozone. Here, we present long-term measurements for ~ 5 years (January 2011 to October 2015) of surface ozone mixing ratios at Nam Co Station, which is a regional background site in the inland Tibetan Plateau. An average surface ozone mixing ratio of 47.6 ± 11.6 ppb was recorded, and a large annual cycle was observed with maximum ozone mixing ratios in the spring and minimum ratios during the winter. The diurnal cycle is characterized by a minimum in the early morning and a maximum in the late afternoon. Nam Co Station represents a background region where surface ozone receives negligible local anthropogenic emissions. Surface ozone at Nam Co Station is mainly dominated by natural processes involving photochemical reactions and potential local vertical mixing. Model results indicate that the study site is affected by the surrounding areas in different seasons and that air masses from the northern Tibetan Plateau lead to increased ozone levels in the summer. In contrast to the surface ozone levels at the edges of the Tibetan Plateau, those at Nam Co Station are less affected by stratospheric intrusions and human activities which makes Nam Co Station representative of vast background areas in the central Tibetan Plateau. By comparing measurements at Nam Co Station with those from other sites in the Tibetan Plateau and beyond, we aim to expand the understanding of ozone cycles and transport processes over the Tibetan Plateau. This work may provide a reference for model simulations in the future.

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

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing ◽

10.1109/jstars.2018.2879666 ◽

2019 ◽

Vol 12 (2) ◽

pp. 533-548 ◽

Cited By ~ 8

Author(s):

Shirui Hao ◽

Lingmei Jiang ◽

Jiancheng Shi ◽

Gongxue Wang ◽

Xiaojing Liu

Keyword(s):

Tibetan Plateau ◽

Snow Cover ◽

The Tibetan Plateau ◽

Fractional Snow Cover

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Review of "Evaluation of snow depth and snow-cover over the Tibetan Plateau in global reanalyses using in-situ and satellite remote sensing observations"

10.5194/tc-2019-49-rc1 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

Remote Sensing ◽

Tibetan Plateau ◽

Snow Cover ◽

Snow Depth ◽

Satellite Remote Sensing ◽

The Tibetan Plateau

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

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-3-w9-57-2019 ◽

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.

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