Monitoring glacial thickness changes in the Tibetan Plateau derived from ICESat data

Monitoring glacier changes is essential for estimating the water mass balance of the Tibetan Plateau. Recent research indicates that glaciers at individual regions on the Tibetan Plateau and surroundings are shrinking and thinning during the last decades. Studies considering large regions often ignored however the impact of locally varying weather conditions and terrain characteristics on glacial evolution, i.e. the impact of orographic precipitation and variation in solar radiation. Our hypothesis is therefore that adjacent glaciers of opposite orientation change in a different way. In this study, we exploit Ice Cloud and land Elevation Satellite (ICESat)/ Geoscience Laser Altimetry System (GLAS) data in combination with the NASA Shuttle Radar Topographic Mission (SRTM) digital elevation model (DEM) and the Global Land Ice Measurements from Space (GLIMS) glacier mask to estimate glacial thickness change trends between 2003 and 2009 on the whole Tibetan Plateau. The results show that 90 glacial areas could be distinguished. Most of observed glacial areas on the Tibetan Plateau are thinning, except for some glaciers in the Northwest. In general, glacial elevations on the whole Tibetan Plateau decreased at an average rate of -0.17 ± 0.47 meters per year (m a-1) between 2003 and 2009, taking together glaciers of any size, distribution, and location of the observed glacial area. Moreover, the results show that glacial elevation changes indeed strongly depend on the relative position in a mountain range.

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Orientation dependent glacial changes at the Tibetan Plateau derived from 2003–2009 ICESat laser altimetry

The Cryosphere Discussions ◽

10.5194/tcd-8-2425-2014 ◽

2014 ◽

Vol 8 (3) ◽

pp. 2425-2463 ◽

Cited By ~ 7

Author(s):

V. H. Phan ◽

R. C. Lindenbergh ◽

M. Menenti

Keyword(s):

Tibetan Plateau ◽

Average Rate ◽

Surface Characteristics ◽

Weather Conditions ◽

Mountain Range ◽

The Tibetan Plateau ◽

Laser Altimetry ◽

Glacier Changes ◽

Elevation Changes ◽

Water Mass Balance

Abstract. Monitoring glacier changes is essential for estimating the water mass balance of the Tibetan Plateau. Recent research indicated that glaciers at individual regions on the Tibetan Plateau and surroundings are shrinking and thinning during the last decades. Studies considering large regions often ignored however impact of locally varying weather conditions and terrain characteristics on glacial evolution, due to orographic precipitation and variation in solar radiation. Our hypothesis is therefore that adjacent glaciers of opposite orientation change in a different way. In this study, we exploit ICESat laser altimetry data in combination with the SRTM DEM and the GLIMS glacier mask to estimate glacial vertical change trends between 2003 and 2009 on the whole Tibetan Plateau. Considering acquisition conditions of ICESat measurements and terrain surface characteristics, annual glacial elevation trends were estimated for 15 different settings. In the final setting, we only include ICESat elevations acquired over terrain that has a slope of below 20° and a roughness at the footprint scale of below 15 m. Within this setting, 90 glacial areas could be distinguished. The results show that most of observed glacial areas on the Tibetan Plateau are thinning, except for notably glaciers in the Northwest. In general, glacial elevations on the whole Tibetan Plateau decreased at an average rate of −0.17 ± 0.47 m per year (m a−1) between 2003 and 2009, but note that the size, distribution, and representativeness of the observed glacial areas are not taken into account. Moreover, the results show that glacial elevation changes indeed strongly depend on the relative position in a mountain range.

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Numerical simulations of Gurenhekou Glacier on the Tibetan Plateau using a full-Stokes ice dynamical model

The Cryosphere Discussions ◽

10.5194/tcd-7-145-2013 ◽

2013 ◽

Vol 7 (1) ◽

pp. 145-173 ◽

Cited By ~ 2

Author(s):

L. Zhao ◽

L. Tian ◽

T. Zwinger ◽

R. Ding ◽

J. Zong ◽

...

Keyword(s):

Tibetan Plateau ◽

21St Century ◽

Climate Models ◽

Average Rate ◽

Regional Climate ◽

Regional Climate Models ◽

Balance Model ◽

Mountain Range ◽

The Tibetan Plateau ◽

The Impact

Abstract. We investigate the impact of climate change on a small Tibetan glacier that is representative of the tens of thousands of mountain glaciers in the region. We apply a three-dimensional, thermo-mechanically coupled full-Stokes model to Gurenhekou Glacier located in the southern Tibetan Plateau. The steep and rugged geometry requires use of such a flow model to simulate the dynamical evolution of the glacier. We parameterize the temperature and mass balance using nearby automatic weather stations and an energy balance model for another glacier in the same mountain range. Summer air temperature increased at 0.02 K a−1 over the past 50 yr, and the glacier has retreated at an average rate of 8.3 m a−1. Prognostic simulations suggest an accelerated retreating rate up to 14 m a−1 for the next 50 yr under continued steady warming, which is consistent with observed increased retreat in the last decade. However, regional climate models suggest a marked increase in warming rate over Tibet during the 21st century, and this rate causes about a 1% per year loss of glaciated area and glacier volume. These changes imply that this small glacier will probably disappear in a century. Although Tibetan glaciers are not particularly sensitive to climate warming, the rather high warming rates predicted by regional climate models combined with the small sizes of most Tibetan glaciers suggest that significant numbers of glaciers will be lost in the region during the 21st century.

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Numerical simulations of Gurenhekou glacier on the Tibetan Plateau

Journal of Glaciology ◽

10.3189/2014jog13j126 ◽

2014 ◽

Vol 60 (219) ◽

pp. 71-82 ◽

Cited By ~ 18

Author(s):

Liyun Zhao ◽

Lide Tian ◽

Thomas Zwinger ◽

Ran Ding ◽

Jibiao Zong ◽

...

Keyword(s):

Tibetan Plateau ◽

21St Century ◽

Climate Models ◽

Average Rate ◽

Regional Climate ◽

Regional Climate Models ◽

Balance Model ◽

The Tibetan Plateau ◽

Surface Mass ◽

The Impact

AbstractWe investigate the impact of climate change on Gurenhekou glacier, southern Tibetan Plateau, which is representative of the tens of thousands of mountain glaciers in the region. We apply a three-dimensional, thermomechanically coupled full-Stokes model to simulate the evolution of the glacier. The steep and rugged bedrock geometry requires use of such a flow model. We parameterize the temperature and surface mass-balance (SMB) uncertainties using nearby automatic weather and meteorological stations, 6 year measured SMB data and an energy-balance model for a nearby glacier. Summer air temperature increased at 0.02 Ka−1 over the past 50 years, and the glacier has retreated at an average rate of 8.3 m a−1. Prognostic simulations suggest an accelerated annual average retreat rate of ~9.1 ma−1 along the central flowline for the next 25 years under continued steady warming. However, regional climate models suggest a marked increase in warming rate over Tibet during the 21st century, and this rate causes about a 0.9 ± 0.3% a−1 loss of glaciated area and 1.1 ± 0.6% a−1 shrinkage of glacier volume. These results, the rather high warming rates predicted and the small sizes of most Tibetan glaciers, suggest that significant numbers of glaciers will be lost in the region during the 21st century.

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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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The impact of atmospheric stability and wind shear on vertical cloud overlap over the Tibetan Plateau

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-7329-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 7329-7343 ◽

Cited By ~ 8

Author(s):

Jiming Li ◽

Qiaoyi Lv ◽

Bida Jian ◽

Min Zhang ◽

Chuanfeng Zhao ◽

...

Keyword(s):

Tibetan Plateau ◽

Wind Shear ◽

Cloud Cover ◽

Atmospheric Stability ◽

Length Scale ◽

The Tibetan Plateau ◽

Total Cloud Cover ◽

Atmospheric Models ◽

The Impact ◽

Overlap Parameter

Abstract. Studies have shown that changes in cloud cover are responsible for the rapid climate warming over the Tibetan Plateau (TP) in the past 3 decades. To simulate the total cloud cover, atmospheric models have to reasonably represent the characteristics of vertical overlap between cloud layers. Until now, however, this subject has received little attention due to the limited availability of observations, especially over the TP. Based on the above information, the main aim of this study is to examine the properties of cloud overlaps over the TP region and to build an empirical relationship between cloud overlap properties and large-scale atmospheric dynamics using 4 years (2007–2010) of data from the CloudSat cloud product and collocated ERA-Interim reanalysis data. To do this, the cloud overlap parameter α, which is an inverse exponential function of the cloud layer separation D and decorrelation length scale L, is calculated using CloudSat and is discussed. The parameters α and L are both widely used to characterize the transition from the maximum to random overlap assumption with increasing layer separations. For those non-adjacent layers without clear sky between them (that is, contiguous cloud layers), it is found that the overlap parameter α is sensitive to the unique thermodynamic and dynamic environment over the TP, i.e., the unstable atmospheric stratification and corresponding weak wind shear, which leads to maximum overlap (that is, greater α values). This finding agrees well with the previous studies. Finally, we parameterize the decorrelation length scale L as a function of the wind shear and atmospheric stability based on a multiple linear regression. Compared with previous parameterizations, this new scheme can improve the simulation of total cloud cover over the TP when the separations between cloud layers are greater than 1 km. This study thus suggests that the effects of both wind shear and atmospheric stability on cloud overlap should be taken into account in the parameterization of decorrelation length scale L in order to further improve the calculation of the radiative budget and the prediction of climate change over the TP in the atmospheric models.

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Simulations of the Impact of Lakes on Local and Regional Climate Over the Tibetan Plateau

ATMOSPHERE-OCEAN ◽

10.1080/07055900.2017.1401524 ◽

2017 ◽

Vol 56 (4) ◽

pp. 230-239 ◽

Cited By ~ 7

Author(s):

Lingjing Zhu ◽

Jiming Jin ◽

Xin Liu ◽

Lei Tian ◽

Qunhui Zhang

Keyword(s):

Tibetan Plateau ◽

Regional Climate ◽

The Tibetan Plateau ◽

The Impact

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Atmospheric brown clouds reach the Tibetan Plateau by crossing the Himalayas

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-6007-2015 ◽

2015 ◽

Vol 15 (11) ◽

pp. 6007-6021 ◽

Cited By ~ 88

Author(s):

Z. L. Lüthi ◽

B. Škerlak ◽

S.-W. Kim ◽

A. Lauer ◽

A. Mues ◽

...

Keyword(s):

Tibetan Plateau ◽

Weather Prediction ◽

Mountain Range ◽

The Tibetan Plateau ◽

Pollution Transport ◽

Synoptic Scale ◽

Gangetic Plain ◽

Dark Light ◽

Air Masses ◽

Pollution Episode

Abstract. The Himalayas and the Tibetan Plateau region (HTP), despite being a remote and sparsely populated area, is regularly exposed to polluted air masses with significant amounts of aerosols including black carbon. These dark, light-absorbing particles are known to exert a great melting potential on mountain cryospheric reservoirs through albedo reduction and radiative forcing. This study combines ground-based and satellite remote sensing data to identify a severe aerosol pollution episode observed simultaneously in central Tibet and on the southern side of the Himalayas during 13–19 March 2009 (pre-monsoon). Trajectory calculations based on the high-resolution numerical weather prediction model COSMO are used to locate the source regions and study the mechanisms of pollution transport in the complex topography of the HTP. We detail how polluted air masses from an atmospheric brown cloud (ABC) over South Asia reach the Tibetan Plateau within a few days. Lifting and advection of polluted air masses over the great mountain range is enabled by a combination of synoptic-scale and local meteorological processes. During the days prior to the event, winds over the Indo-Gangetic Plain (IGP) are generally weak at lower levels, allowing for accumulation of pollutants and thus the formation of ABCs. The subsequent passing of synoptic-scale troughs leads to southwesterly flow in the middle troposphere over northern and central India, carrying the polluted air masses across the Himalayas. As the IGP is known to be a hotspot of ABCs, the cross-Himalayan transport of polluted air masses may have serious implications for the cryosphere in the HTP and impact climate on regional to global scales. Since the current study focuses on one particularly strong pollution episode, quantifying the frequency and magnitude of similar events in a climatological study is required to assess the total impact.

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The impact of atmospheric dynamics on vertical cloud overlap over the Tibetan Plateau

10.5194/acp-2017-642 ◽

2017 ◽

Author(s):

Jiming Li ◽

Qiaoyi Lv ◽

Bida Jian ◽

Min Zhang ◽

Chuanfeng Zhao ◽

...

Keyword(s):

Tibetan Plateau ◽

Wind Shear ◽

Cloud Cover ◽

Atmospheric Stability ◽

Separation Distance ◽

Atmospheric Dynamics ◽

The Tibetan Plateau ◽

Total Cloud Cover ◽

The Impact ◽

Overlap Parameter

Abstract. The accurate representation of cloud vertical overlap in atmospheric models is particularly significant for predicting the total cloud cover and for the calculations related to the radiative budget in these models. However, it has received too little attention due to the limited observation, especially over the Tibetan Plateau (TP). In this study, 4 years (2007–2010) of data from the CloudSat cloud product and collocated ERA-Interim reanalysis product were analyzed to examine the seasonal and zonal variations of cloud overlap properties over the TP region, and evaluate the effect of atmospheric dynamics on cloud overlap. Unique characteristics of cloud overlap over the TP have been found. The statistical results show that the random overlap assumption slightly underestimates the total cloud coverage for discontinuous cloud layers over the TP, whereas the overlap parameter α for continuous cloud sharply decrease from maximum to random overlap with an increase of layer distance, eventually trending towards a minimal overlap (e.g., negative α values) as the cloud layer separation distance exceeds 1.5 km. Compared with the global averaged cloud overlap characteristics, the proportion of minimal overlap over the TP is significant high (about 41 %). It may be associated with the unique topographical forcing and thermos-dynamical environment of the TP. As a result, we propose a valid scheme for quantifying the degree of cloud overlap over the TP through a linear combination of the maximum and minimum overlap, and further parameterize decorrelation length scale L as a function of wind shear and atmospheric stability. Compared with other parameterizations, the new scheme reduces the bias between predicted and observed cloud covers. These results thus indicate that effects of wind shear and atmospheric stability on cloud overlap should both be taken into account in the parameterization of overlap parameter to improve the simulation of total cloud cover in models.

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Plants and Microbes Mediate the Shift in Ecosystem Multifunctionality From Low to High Patterns Across Alpine Grasslands on the Tibetan Plateau

Frontiers in Plant Science ◽

10.3389/fpls.2021.760599 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yi Wang ◽

Miao Liu ◽

Youchao Chen ◽

Tao Zeng ◽

Xuyang Lu ◽

...

Keyword(s):

Tibetan Plateau ◽

Correlation Coefficients ◽

Terrestrial Ecosystems ◽

Alpine Grassland ◽

Future Climate Change ◽

The Tibetan Plateau ◽

Grassland Ecosystem ◽

The Impact ◽

Ecosystem Multifunctionality ◽

Alpine Grassland Ecosystem

Both plant communities and soil microbes have been reported to be correlated with ecosystem multifunctionality (EMF) in terrestrial ecosystems. However, the process and mechanism of aboveground and belowground communities on different EMF patterns are not clear. In order to explore different response patterns and mechanisms of EMF, we divided EMF into low (<0) and high patterns (>0). We found that there were contrasting patterns of low and high EMF in the alpine grassland ecosystem on the Tibetan Plateau. Specifically, compared with low EMF, environmental factors showed higher sensitivity to high EMF. Soil properties are critical factors that mediate the impact of community functions on low EMF based on the change of partial correlation coefficients from 0 to 0.24. In addition, plant community functions and microbial biomass may mediate the shift of EMF from low to high patterns through the driving role of climate across the alpine grassland ecosystem. Our findings will be vital to clarify the mechanism for the stability properties of grassland communities and ecosystems under ongoing and future climate change.

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The South Asia Monsoon Break Promotes Grass Growth on the Tibetan Plateau

10.5194/egusphere-egu21-5776 ◽

2021 ◽

Author(s):

Yanghang Ren ◽

Kun Yang ◽

Han Wang

Keyword(s):

Soil Moisture ◽

Tibetan Plateau ◽

Solar Radiation ◽

Climate Variability ◽

South Asia ◽

The Tibetan Plateau ◽

The South ◽

Central Eastern ◽

Grass Growth ◽

The Impact

<p>As region that is highly sensitive to global climate change, the Tibetan Plateau (TP) experiences an intra-seasonal soil water deficient due to the reduced precipitation during the South Asia monsoon (SAM) break. Few studies have investigated the impact of the SAM break on TP ecological processes, although a number of studies have explored the effects of inter-annual and decadal climate variability. In this study, the response of vegetation activity to the SAM break was investigated. The data used are: (1) soil moisture from in situ, satellite remote sensing and data assimilation; and (2) the Normalized Difference Vegetation Index (NDVI) and Solar-Induced chlorophyll Fluorescence&#160;(SIF). We found that in the region impacted by SAM break, which is distributed in the central-eastern part of TP, photosynthesis become more active during the SAM break. And temporal variability in the photosynthesis of this region is controlled mainly by solar radiation variability and has little sensitivity to soil moisture. We adopted a diagnostic process-based modeling approach to examine the causes of enhanced plant activity during the SAM break on the central-eastern TP. Our analysis indicates that active photosynthetic behavior in the reduced precipitation is stimulated by increases in solar radiation absorbed and temperature. This study highlights the importance of sub-seasonal climate variability for characterizing the relationship between vegetation and climate.</p>

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