scholarly journals Seasonal Dynamics of a Temperate Tibetan Glacier Revealed by High-Resolution UAV Photogrammetry and In Situ Measurements

2020 ◽  
Vol 12 (15) ◽  
pp. 2389
Author(s):  
Wei Yang ◽  
Chuanxi Zhao ◽  
Matthew Westoby ◽  
Tandong Yao ◽  
Yongjie Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Warm Season ◽  
Cold Season ◽  
Seasonal Dynamic ◽  
Surface Elevation ◽  
The Tibetan Plateau ◽  
Ablation Zone ◽  
Spring Precipitation ◽  
Ice Surface ◽  
Seasonal Signals

The seasonal dynamic changes of Tibetan glaciers have seen little prior investigation, despite the increase in geodetic studies of multi-year changes. This study compares seasonal glacier dynamics (“cold” and “warm” seasons) in the ablation zone of Parlung No. 4 Glacier, a temperate glacier in the monsoon-influenced southeastern Tibetan Plateau, by using repeat unpiloted aerial vehicle (UAV) surveys combined with Structure-from-Motion (SfM) photogrammetry and ground stake measurements. Our results showed that the surveyed ablation zone had a mean change of −2.7 m of ice surface elevation during the period of September 2018 to October 2019 but is characterized by significant seasonal cyclic variations with ice surface elevation lifting (+2.0 m) in the cold season (September 2018 to June 2019) but lowering (−4.7 m) in the warm season (June 2019 to October 2019). Over an annual timescale, surface lowering was greatly suppressed by the resupply of ice from the glacier’s accumulation area—the annual emergence velocity compensates for about 55% of surface ablation in our study area. Cold season emergence velocities (3.0 ± 1.2 m) were ~5-times larger than those observed in the warm season (0.6 ± 1.0 m). Distinct spring precipitation patterns may contribute to these distinct seasonal signals. Such seasonal dynamic conditions are possibly critical for different glacier responses to climate change in this region of the Tibetan Plateau, and perhaps further afield.

scholarly journals Seasonal ice dynamics in the lower ablation zone of Dagongba Glacier, southeastern Tibetan Plateau, from multitemporal UAV images

2021 ◽  
pp. 1-15
Author(s):  
Yin Fu ◽  
Qiao Liu ◽  
Guoxiang Liu ◽  
Bo Zhang ◽  
Rui Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Seasonal Dynamics ◽  
Warm Season ◽  
Cold Season ◽  
Surface Elevation ◽  
Surface Velocity ◽  
Ablation Zone ◽  
Glacier Surface ◽  
Ice Dynamics ◽  
Southeastern Tibetan Plateau

Abstract Most glaciers on the Tibetan Plateau have experienced continuous mass losses in response to global warming. However, the seasonal dynamics of glaciers on the southeastern Tibetan Plateau have rarely been reported in terms of glacier surface elevation and velocity. This paper presents a first attempt to explore the seasonal dynamics of the debris-covered Dagongba Glacier within the southeastern Tibetan Plateau. We use the multitemporal unoccupied aerial vehicle images collected over the lower ablation zone on 8 June and 17 October 2018, and 13 May 2019, and then perform an analysis concerning climatic fluctuations. The results reveal that the mean surface elevation decrease of the Dagongba Glacier during the warm season ( $2.81\pm 0.44$ m) was remarkably higher than the cold season ( $0.72\pm 0.45$ m). Particularly notable glacier surface elevation changes were found around supraglacial lakes and ice cliffs where ice ablation rates were $\sim$ 3 times higher than the average. In addition, a larger longitudinal decline of glacier surface velocity was observed in the warm season than that in the cold season. In terms of further comparative analysis, the Dagongba Glacier experienced a decrease in surface velocity between 1982–83 and 2018–19, with a decrease in the warm season possibly twice as large as that in the cold season.

scholarly journals Isotopic constraints on atmospheric sulfate formation pathways in the Mt. Everest region, southern Tibetan Plateau

2021 ◽  
Author(s):  
Kun Wang ◽  
Shohei Hattori ◽  
Mang Lin ◽  
Sakiko Ishino ◽  
Becky Alexander ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Warm Season ◽  
Cold Season ◽  
Sulfur Cycle ◽  
Formation Mechanisms ◽  
The Tibetan Plateau ◽  
Sampling Campaign ◽  
Water Ph ◽  
Southern Tibetan Plateau ◽  
Sulfate Formation

Abstract. As an important atmosphere constituent, sulfate aerosols exert profound impacts on climate, ecological environment, and human health. The Tibetan Plateau (TP), identified as the Third Pole, contains the largest land ice masses outside the poles and has attracted wide attention on its environment and climatic change. However, the mechanisms of sulfate formation in this specific region remain poorly characterized. Oxygen-17 anomaly (Δ17O) has been used as a probe to constrain the relative importance of different pathways leading to sulfate formation. Here, we report the Δ17O values in atmospheric sulfate collected at a remote site in the Mt. Everest region to decipher the possible formation mechanisms of sulfate in such a pristine environment. Throughout the sampling campaign (April–September 2018), the Δ17O in non-dust sulfate show an average of 1.7 ± 0.5 ‰ which is higher than most existing data in modern atmospheric sulfate. The seasonality of Δ17O in non-dust sulfate exhibits high values in the pre-monsoon and low values in the monsoon, opposite to the seasonality in Δ17O for both sulfate and nitrate (i.e., minima in warm season and maxima in cold season) observed from diverse geographic sites. This high Δ17O in non-dust sulfate found in this region clearly indicates the important role of the S(IV) + O3 pathway in atmospheric sulfate formation promoted by high cloud water pH condition. Overall, our study provides an observational constraint on atmospheric acidity in altering sulfate formation pathways particularly in dust-rich environments, and such identification of key processes provides an important basis for a better understanding of the sulfur cycle in the TP.

scholarly journals Isotopic constraints on atmospheric sulfate formation pathways in the Mt. Everest region, southern Tibetan Plateau

2021 ◽  
Vol 21 (10) ◽  
pp. 8357-8376
Author(s):  
Kun Wang ◽  
Shohei Hattori ◽  
Mang Lin ◽  
Sakiko Ishino ◽  
Becky Alexander ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Warm Season ◽  
Cold Season ◽  
Sulfur Cycle ◽  
Formation Mechanisms ◽  
The Tibetan Plateau ◽  
Sampling Campaign ◽  
Water Ph ◽  
Southern Tibetan Plateau ◽  
Sulfate Formation

Abstract. As an important atmosphere constituent, sulfate aerosols exert profound impacts on climate, the ecological environment, and human health. The Tibetan Plateau (TP), identified as the “Third Pole”, contains the largest land ice masses outside the poles and has attracted widespread attention for its environment and climatic change. However, the mechanisms of sulfate formation in this specific region still remain poorly characterized. An oxygen-17 anomaly (Δ17O) has been used as a probe to constrain the relative importance of different pathways leading to sulfate formation. Here, we report the Δ17O values in atmospheric sulfate collected at a remote site in the Mt. Everest region to decipher the possible formation mechanisms of sulfate in such a pristine environment. Throughout the sampling campaign (April–September 2018), the Δ17O in non-dust sulfate show an average of 1.7 ‰±0.5 ‰, which is higher than most existing data on modern atmospheric sulfate. The seasonality of Δ17O in non-dust sulfate exhibits high values in the pre-monsoon and low values in the monsoon, opposite to the seasonality in Δ17O for both sulfate and nitrate (i.e., minima in the warm season and maxima in the cold season) observed from diverse geographic sites. This high Δ17O in non-dust sulfate found in this region clearly indicates the important role of the S(IV)+O3 pathway in atmospheric sulfate formation promoted by conditions of high cloud water pH. Overall, our study provides an observational constraint on atmospheric acidity in altering sulfate formation pathways, particularly in dust-rich environments, and such identification of key processes provides an important basis for a better understanding of the sulfur cycle in the TP.

Dynamic and Thermodynamic Relations of Distinctive Stratus Clouds on the Lee Side of the Tibetan Plateau in the Cold Season

2013 ◽  
Vol 26 (21) ◽  
pp. 8378-8391 ◽  
Author(s):  
Yi Zhang ◽  
Rucong Yu ◽  
Jian Li ◽  
Weihua Yuan ◽  
Minghua Zhang
Keyword(s):  
Tibetan Plateau ◽  
Large Scale ◽  
Eastern China ◽  
Cold Season ◽  
Water Vapor Transport ◽  
The Tibetan Plateau ◽  
Primary Role ◽  
Moist Air ◽  
Low Level ◽  
Stratus Clouds

Abstract Given the large discrepancies that exist in climate models for shortwave cloud forcing over eastern China (EC), the dynamic (vertical motion and horizontal circulation) and thermodynamic (stability) relations of stratus clouds and the associated cloud radiative forcing in the cold season are examined. Unlike the stratus clouds over the southeastern Pacific Ocean (as a representative of marine boundary stratus), where thermodynamic forcing plays a primary role, the stratus clouds over EC are affected by both dynamic and thermodynamic factors. The Tibetan Plateau (TP)-forced low-level large-scale lifting and high stability over EC favor the accumulation of abundant saturated moist air, which contributes to the formation of stratus clouds. The TP slows down the westerly overflow through a frictional effect, resulting in midlevel divergence, and forces the low-level surrounding flows, resulting in convergence. Both midlevel divergence and low-level convergence sustain a rising motion and vertical water vapor transport over EC. The surface cold air is advected from the Siberian high by the surrounding northerly flow, causing low-level cooling. The cooling effect is enhanced by the blocking of the YunGui Plateau. The southwesterly wind carrying warm, moist air from the east Bay of Bengal is uplifted by the HengDuan Mountains via topographical forcing; the midtropospheric westerly flow further advects the warm air downstream of the TP, moistening and warming the middle troposphere on the lee side of the TP. The low-level cooling and midlevel warming together increase the stability. The favorable dynamic and thermodynamic large-scale environment allows for the formation of stratus clouds over EC during the cold season.

scholarly journals Characteristics of Deep Convective Systems and Initiation during Warm Seasons over China and Its Vicinity

2021 ◽  
Vol 13 (21) ◽  
pp. 4289
Author(s):  
Yang Li ◽  
Yubao Liu ◽  
Yun Chen ◽  
Baojun Chen ◽  
Xin Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
South China ◽  
Warm Season ◽  
Statistical Characteristics ◽  
The Tibetan Plateau ◽  
Spatiotemporal Resolution ◽  
Convective Systems ◽  
Seasonal And Diurnal Variations ◽  
Deep Convective Systems ◽  
Guizhou Plateau

The spatiotemporal statistical characteristics of warm-season deep convective systems, particularly deep convective systems initiation (DCSI), over China and its vicinity are investigated using Himawari-8 geostationary satellite measurements collected during April-September from 2016 to 2020. Based on a satellite brightness temperature multiple-threshold convection identification and tracking method, a total of 47593 deep convective systems with lifetimes of at least 3 h were identified in the region. There are three outstanding local maxima in the region, located in the southwestern, central and eastern Tibetan Plateau and Yunnan-Guizhou Plateau, followed by a region of high convective activities in South China. Most convective systems are developed over the Tibetan Plateau, predominantly eastward-moving, while those developed in Yunnan-Guizhou Plateau and South China mostly move westward and southwestward. The DSCI occurrences become extremely active after the onset of the summer monsoon and tend to reach a maximum in July and August, with a diurnal peak at 11–13 LST in response to the enhanced solar heating and monsoon flows. Several DCSI hotspots are identified in the regions of inland mountains, tropical islands and coastal mountains during daytime, but in basins, plains and coastal areas during nighttime. DCSI over land and oceans exhibits significantly different sub-seasonal and diurnal variations. Oceanic DCSI has an ambiguous diurnal variation, although its sub-seasonal variation is similar to that over land. It is demonstrated that the high spatiotemporal resolution satellite dataset provides rich information for understanding the convective systems over China and vicinity, particularly the complex terrain and oceans where radar observations are sparse or none, which will help to improve the convective systems and initiation nowcasting.

Diurnal Variations of Warm-Season Precipitation East of the Tibetan Plateau over China

2011 ◽  
Vol 139 (9) ◽  
pp. 2790-2810 ◽  
Author(s):  
Xinghua Bao ◽  
Fuqing Zhang ◽  
Jianhua Sun
Keyword(s):  
Tibetan Plateau ◽  
Warm Season ◽  
Propagation Speed ◽  
Western Pacific Subtropical High ◽  
Diurnal Variations ◽  
The Tibetan Plateau ◽  
Diurnal Cycles ◽  
Thermally Driven ◽  
The Difference ◽  
Precipitation Cycle

This study explores the diurnal variations of the warm-season precipitation to the east of the Tibetan Plateau over China using the high-resolution NOAA/Climate Prediction Center morphing technique (CMORPH) precipitation data and the Global Forecast System (GFS) gridded analyses during mid-May to mid-August of 2003–09. Complementary to the past studies using satellite or surface observations, it is found that there are strong diurnal variations in the summertime precipitation over the focus domain to the east of the Tibetan Plateau. These diurnal precipitation cycles are strongly associated with several thermally driven regional mountain–plains solenoids due to the differential heating between the Tibetan Plateau, the highlands, the plains, and the ocean. The diurnal cycles differ substantially from region to region and during the three different month-long periods: the pre-mei-yu period (15 May–15 June), the mei-yu period (15 June–15 July), and the post-mei-yu period (15 July–15 August). In particular, there is a substantial difference in the propagation speed and eastward extent of the peak phase of the dominant diurnal precipitation cycle that is originated from the Tibetan Plateau. This diurnal peak has a faster (slower) eastward propagation speed, the more (less) coherent propagation duration, and thus covers the longest (shortest) distance to the east during the pre-mei-yu (post-mei-yu) period than that during the mei-yu period. The differences in the mean midlatitude westerly flow and in the positioning and strength of the western Pacific subtropical high during different periods are the key factors in explaining the difference in the propagation speed and the eastward extent of this dominant diurnal precipitation cycle.

scholarly journals Climatology of Cloud Phase, Cloud Radiative Effects and Precipitation Properties over the Tibetan Plateau

2021 ◽  
Vol 13 (3) ◽  
pp. 363
Author(s):  
Jing Wang ◽  
Bida Jian ◽  
Guoyin Wang ◽  
Yuxin Zhao ◽  
Yarong Li ◽  
...  
Keyword(s):  
Warm Season ◽  
Supercooled Water ◽  
Cold Season ◽  
Cloud Fraction ◽  
Mixed Phase ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
Southeastern Part ◽  
Precipitation Frequency ◽  
Ice Cloud

Current passive sensors fail to accurately identify cloud phase, thus largely limiting the quantification of radiative contributions and precipitation of different cloud phases over the Tibet Plateau (TP), especially for the mixed-phase and supercooled water clouds. By combining the 4 years of (January 2007–December 2010) cloud phase (2B-CLDCLASS-LIDAR), radiative fluxes (2B-FLXHR-LIDAR), and precipitation (2C-PRECIP-COLUMN) products from CloudSat, this study systematically quantifies the radiative contribution of cloud phases and precipitation over the TP. Statistical results indicate that the ice cloud frequently occurs during the cold season, while mixed-phase cloud fraction is more frequent during the warm season. In addition, liquid clouds exhibit a weak seasonal variation, and the relative cloud fraction is very low, but supercooled water cloud has a larger cloud distribution (the value reaches about 0.24) than those of warm water clouds in the eastern part of the TP during the warm season. Within the atmosphere, the ice cloud has the largest radiative contribution during the cold season, the mixed-phase cloud is the second most important cloud phase for the cloud radiative contribution during the warm season, and supercooled water clouds’ contribution is particularly important during the cold season. In particular, the precipitation frequency over the TP is mainly dominated by the ice and mixed-phase clouds and is larger over the southeastern part of the TP during the warm season.

scholarly journals Investigation of the ice surface albedo in the Tibetan Plateau lakes based on the field observation and MODIS products

2018 ◽  
Vol 64 (245) ◽  
pp. 506-516 ◽  
Author(s):  
ZHAOGUO LI ◽  
YINHUAN AO ◽  
SHIHUA LYU ◽  
JIAHE LANG ◽  
LIJUAN WEN ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Surface Temperature ◽  
Time Windows ◽  
The Tibetan Plateau ◽  
Lake Ice ◽  
Ice Surface ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Ice Surface Temperature ◽  
Relationship Of

ABSTRACTThe Tibetan Plateau (TP) lakes are sensitive to climate change due to ice-albedo feedback, but almost no study has paid attention to the ice albedo of TP lakes and its potential impacts. Here we present a recent field experiment for observing the lake ice albedo in the TP, and evaluate the applicability of the Moderate Resolution Imaging Spectroradiometer (MODIS) products as well as ice-albedo parameterizations. Most of the observed lake ice albedos on TP are <0.12, and the clear blue ice albedo is only 0.075, much lower than reported in the previous studies. Even that of ice covered with snow patches is only 0.212. MOD10A1 albedo product has the best agreement with observations, followed by those of MYD10A1. MCD43A3 product is consistently higher than the observations. Due to an error of snow flag and inconsistent time windows in MCD43A2 and MCD43A3, at certain times, the albedo of the ice without snow is even higher than that covered with snow. When the solar zenith angle is not considered, there is no significant correlation between the albedo and the ice surface temperature. None of the existing ice-albedo parameterizations can reproduce well the observed relationship of the albedo and surface temperature.

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