On the relationship between Tibetan snow cover, the Tibetan plateau monsoon and the Indian summer monsoon

2004 ◽  
Vol 31 (14) ◽  
Author(s):  
Hongxu Zhao
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
The Tibetan Plateau ◽  
The Relationship

scholarly journals First measurement of atmospheric mercury species in Qomolangma Natural Nature Preserve, Tibetan Plateau, and evidence oftransboundary pollutant invasion

2019 ◽  
Vol 19 (2) ◽  
pp. 1373-1391 ◽  
Author(s):  
Huiming Lin ◽  
Yindong Tong ◽  
Xiufeng Yin ◽  
Qianggong Zhang ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Transition Period ◽  
Atmospheric Pollutants ◽  
Mercury Species ◽  
The Tibetan Plateau ◽  
Monsoon Period ◽  
Air Masses ◽  
Nature Preserve

Abstract. Located in the world's “third pole” and a remote region connecting the Indian plate and the Eurasian plate, Qomolangma National Nature Preserve (QNNP) is an ideal region to study the long-range transport of atmospheric pollutants. In this study, gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particle-bound mercury (PBM) were continuously measured during the Indian monsoon transition period in QNNP. A slight increase in the GEM concentration was observed from the period preceding the Indian summer monsoon (1.31±0.42 ng m−3) to the Indian summer monsoon period (1.44±0.36 ng m−3), while significant decreases were observed in the GOM and PBM concentrations, with concentrations decreasing from 35.2±18.6 to 19.3±10.9 pg m−3 (p < 0.001) for GOM and from 30.5±12.5 to 24.9±19.8 pg m−3 (p < 0.001) for PBM. A unique daily pattern was observed in QNNP with respect to the GEM concentration, with a peak value before sunrise and a low value at noon. Relative to the (low) GEM concentrations, GOM concentrations (with a mean value of 21.4±13.4 pg m−3, n=1239) in this region were relatively high compared with the measured values in some other regions of China. A cluster analysis indicated that the air masses transported to QNNP changed significantly at different stages of the monsoon, and the major potential mercury (Hg) sources shifted from northern India and western Nepal to eastern Nepal and Bangladesh. As there is a large area covered in glaciers in QNNP, local glacier winds could increase the transboundary transport of pollutants and transport polluted air masses to the Tibetan Plateau. The atmospheric Hg concentration in QNNP in the Indian summer monsoon period was influenced by transboundary Hg flows. This highlights the need for a more specific identification of Hg sources impacting QNNP and underscores the importance of international cooperation regarding global Hg controls.

scholarly journals Regionalization of seasonal precipitation over the Tibetan Plateau and associated large-scale atmospheric systems

2020 ◽  
pp. 1-45
Author(s):  
Hui-Wen Lai ◽  
Hans W. Chen ◽  
Julia Kukulies ◽  
Tinghai Ou ◽  
Deliang Chen
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Large Scale ◽  
Late Summer ◽  
Early Summer ◽  
The Tibetan Plateau ◽  
Summer Peak ◽  
Precipitation Seasonality ◽  
Winter Peak

AbstractPrecipitation over the Tibetan Plateau (TP) has major societal impacts in South and East Asia, but its spatiotemporal variations are not well understood mainly because of the sparsely distributed in-situ observation sites. With help of the Global Precipitation Measurement satellite product IMERG and ERA5 reanalysis, distinct precipitation seasonality features over the TP were objectively classified using a self-organizing map algorithm fed with ten-day averaged precipitation from 2000 to 2019. The classification reveals three main precipitation regimes with distinct seasonality of precipitation: winter peak, centered at the western plateau; early summer peak, found on the eastern plateau; and late summer peak, mainly located on the southwestern plateau. On a year-to-year basis, the winter peak regime is relatively robust, while the early summer and late summer peak regimes tend to shift mainly between the central and northern TP, but are robust in the eastern and southwestern TP. A composite analysis shows that the winter peak regime experiences larger amounts of precipitation in winter and early spring when the westerly jet is anomalously strong to the north of the TP. Precipitation variations in the late summer peak regime are associated with intensity changes in the South Asian High and Indian summer monsoon. The precipitation in the early summer peak regime is correlated with the Indian summer monsoon together with anticyclonic circulation over the western North Pacific. The results provide a basic understanding of precipitation seasonality variations over the TP and associated large-scale conditions.

scholarly journals First Observation of Mercury Species on an Important Water Vapor Channel in the Southeast Tibetan Plateau

2021 ◽  
Author(s):  
Huiming Lin ◽  
Yindong Tong ◽  
Chenghao Yu ◽  
Long Chen ◽  
Xiufeng Yin ◽  
...  
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Northeast India ◽  
Atmospheric Pollutants ◽  
Mercury Species ◽  
The Tibetan Plateau ◽  
Long Distance ◽  
Vapor Channel

Abstract. The Tibetan Plateau is generally considered to be a significantly clean area owing to its high altitude; however, the transport of atmospheric pollutants from the Indian subcontinent to the Tibetan Plateau has infected the Tibetan environments. Nyingchi is located at the end of an important water vapor channel. In this study, continuous monitoring of gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particle-bound mercury (PBM) was conducted in Nyingchi from March 30 to September 3, 2019, to study the influence of the Indian summer monsoon (ISM) on the origin, transport and behavior of mercury. The atmospheric Hg concentrations during the preceding Indian summer monsoon (PISM) period (1.20 ± 0.35 ng m−3, 13.5 ± 7.3 pg m−3, and 11.4 ± 4.8 pg m−3 for GEM, GOM, and PBM, respectively) were relatively higher than those during the ISM period (0.95 ± 0.21 ng m−3, 12.7 ± 14.3 pg m−3 and 8.8 ± 6.0 pg m−3). The average annual total gaseous mercury concentration in the Nyingchi region was obtained using a passive sampler as 1.12 ± 0.28 ng m−3. The GEM concentration showed that the sampling area was very clean. The GEM has several patterns of daily variation during different periods. Stable high GEM concentrations occur at night during PISM, which may be related to the nocturnal boundary layer. High values occurring in the late afternoon during the ISM may be related to long-range transport. The results of the trajectory model demonstrate that the sources of pollutants at Nyingchi are different under the control of different airflow fields. During westerly circulation, pollutants mainly originate from northeast India or Nepal. During the ISM period, the pollutants mainly originate from northeast India, or the Bay of Bengal, and the Indian Ocean. The strong precipitation and vegetation effects on Hg during the ISM resulted in low Hg concentrations transmitted to Nyingchi during this period. Further, principal component analysis showed that long-distance transport, local emissions, meteorological factors, and snowmelt factors are the main factors affecting the local Hg concentration in Nyingchi.

scholarly journals A climatological perspective of deep convection penetrating the TTL during the Indian summer monsoon from the AVHRR and MODIS instruments

2010 ◽  
Vol 10 (2) ◽  
pp. 2809-2834 ◽  
Author(s):  
A. Devasthale ◽  
S. Fueglistaler
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Bay Of Bengal ◽  
Deep Convection ◽  
Radiative Heating ◽  
The Tibetan Plateau ◽  
Brightness Temperatures ◽  
Avhrr Data ◽  
The Impact

Abstract. The impact of very deep convection on the water budget and thermal structure of the tropical tropopause layer is still not well quantified, not least because of limitations imposed by the available observation techniques. Here, we present detailed analysis of the climatology of the cloud top brightness temperatures as indicators of deep convection during the Indian summer monsoon, and the variations therein due to active and break periods. We make use of the recently newly processed data from the Advanced Very High Resolution Radiometer (AVHRR) at a nominal spatial resolution of 4 km. Using temperature thresholds from the Atmospheric Infrared Sounder (AIRS), the AVHRR brightness temperatures are converted to climatological mean (2003–2008) maps of cloud amounts at 200, 150 and 100 hPa. Further, we relate the brightness temperatures to the level of zero radiative heating, which may allow a coarse identification of convective detrainment that will subsequently ascend into the stratosphere. The AVHRR data for the period 1982–2006 are used to document the differences in deep convection between active and break conditions of the monsoon. The analysis of AVHRR data is complemented with cloud top pressure and optical depth statistics (for the period 2003–2008) from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua satellite. Generally, the two sensors provide a very similar description of deep convective clouds. Our analysis shows that most of the deep convection occurs over the Bay of Bengal and Central Northeast India. Very deep convection over the Tibetan plateau is comparatively weak, and may play only a secondary role in troposphere-to-stratosphere transport. The deep convection over the Indian monsoon region is most frequent in July/August, but the very highest convection (coldest tops, penetrating well into the TTL) occurs in May/June. Large variability in convection reaching the TTL is due to monsoon break/active periods. During the monsoon break period, deep convection reaching the TTL is almost entirely absent in the western part of the study area (i.e. 60°–75° E), while the distribution over the Bay of Bengal and the Tibetan Plateau is less affected. Although the active conditions occur less frequently than the break conditions, they may have a larger bearing on the composition of the TTL within the monsoonal anticyclone, and tracer transport into the stratosphere because of deep convection occurring over anthropogenically more polluted regions.

scholarly journals Synergy Effects of the Indian Summer Monsoon and the Tibetan Plateau Heating on Summer Rainfall over North China

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Siwen Zhao ◽  
Jie Zhang ◽  
Zhihong Lv
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Rossby Wave ◽  
North Africa ◽  
Indian Summer Monsoon ◽  
North China ◽  
Summer Rainfall ◽  
The Tibetan Plateau ◽  
The Pacific

An analysis based on July-August precipitation reveals that there is a tripole pattern of the precipitation distribution, that is, significantly increased rainfall over North China (NC) is related to the increased rainfall over the Indian subcontinent (IS) and the decreased rainfall over the southeastern Tibetan Plateau (TP) and vice versa, that corresponds to the Indian summer monsoon (ISM) and TP heating pattern, which are interactive. Therefore, it is necessary to investigate the effect of NC rainfall-related atmospheric circulation and the physical linkage with the two thermal forcings together. The linear baroclinic model (LBM) is applied to determine the dynamics of the process. The results show that an enhanced ISM is accompanied by reduced TP heating, favors convection and easterly anomaly over the IS, and produces a Gill-type Rossby wave that affects the vorticity over North Africa. Meanwhile, there is another Rossby wave originating in North Africa and moving eastward to the Pacific Ocean, which interferes with circulation at mid- to high-latitudes, i.e., it strengthens the cyclone over the Baikal region and stretches the western Pacific subtropical high (WPSH) northward to northeastern Asia, and results in abundant water vapor transported to NC. Furthermore, the strong convection over the IS excites the Kelvin waves over the equatorial region, which moves eastward and generates anticyclones over Philippines, consequently leading to the Pacific-Japan (PJ) pattern. The PJ pattern cooperates with the wave train at midlatitudes, resulting in abundant water vapor being transported to NC. The summer rainfall over NC is therefore modulated by synergistic effect of both the ISM and TP heating.

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.

Regionalization of seasonal precipitation over the Tibetan Plateau

2021 ◽  
Author(s):  
Hui-Wen Lai ◽  
Hans W. Chen ◽  
Julia Kukulies ◽  
Tinghai Ou ◽  
Deliang Chen
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
In Situ Observation ◽  
Western Region ◽  
Eastern Region ◽  
The Tibetan Plateau ◽  
Precipitation Regimes ◽  
The Western Region

&lt;p&gt;The Tibetan Plateau (TP) is the &amp;#8220;water tower&amp;#8221; of Asia and is the origin of most major rivers that provide water resources supporting countries in Asia. Changes in precipitation over the plateau play an important role in the water management in those areas, but the spatiotemporal variations of the precipitation over the TP are not well understood mainly because of the sparsely distributed in-situ observation sites. This study takes advantage of the newly available high-resolution ERA5 reanalysis and the Global&amp;#160;Precipitation&amp;#160;Measurement satellite product IMERG together with in-situ observations to characterize the seasonality of precipitation over the TP using a self-organizing map algorithm fed with precipitation data from 2000 to 2019. Specifically, this study aims to (1) identify regions with distinct seasonality in precipitation, (2) determine the interannual variability in the classification and regional precipitation, and (3) explore the roles played by large-scale atmospheric circulations on the seasonality of regional precipitation. The classification reveals three major precipitation regimes in the TP centered at the western, southwestern, and eastern plateau. On a year-to-year basis, the western region is relatively robust, while the southwestern and eastern regions tend to shift mainly between the central and northern TP. A composite analysis shows that the western region experiences larger amounts of precipitation in winter and early spring when the westerly jet is anomalously strong to the north of the TP. Precipitation variations in the southwestern region are associated with intensity changes in the South Asian High and Indian summer monsoon. The precipitation in the eastern region is correlated with the Indian summer monsoon and anticyclonic circulation over the western North Pacific. Our findings provide a better understanding of the regional and interannual variations of precipitation regimes over the TP, and could help to interpret future changes in precipitation regimes due to climate change.&lt;/p&gt;

scholarly journals A climatological perspective of deep convection penetrating the TTL during the Indian summer monsoon from the AVHRR and MODIS instruments

2010 ◽  
Vol 10 (10) ◽  
pp. 4573-4582 ◽  
Author(s):  
A. Devasthale ◽  
S. Fueglistaler
Keyword(s):  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Bay Of Bengal ◽  
Deep Convection ◽  
Radiative Heating ◽  
The Tibetan Plateau ◽  
Brightness Temperatures ◽  
Avhrr Data ◽  
The Impact

Abstract. The impact of very deep convection on the water budget and thermal structure of the tropical tropopause layer is still not well quantified, not least because of limitations imposed by the available observation techniques. Here, we present detailed analysis of the climatology of the cloud top brightness temperatures as indicators of deep convection during the Indian summer monsoon, and the variations therein due to active and break periods. We make use of the recently newly processed data from the Advanced Very High Resolution Radiometer (AVHRR) at a nominal spatial resolution of 4 km. Using temperature thresholds from the Atmospheric Infrared Sounder (AIRS), the AVHRR brightness temperatures are converted to climatological mean (2003–2008) maps of cloud amounts at 200, 150 and 100 hPa. Further, we relate the brightness temperatures to the level of zero radiative heating, which may allow a coarse identification of convective detrainment that will subsequently ascend into the stratosphere. The AVHRR data for the period 1982–2006 are used to document the differences in deep convection between active and break conditions of the monsoon. The analysis of AVHRR data is complemented with cloud top pressure and optical depth statistics (for the period 2003–2008) from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Aqua satellite. Generally, the two sensors provide a very similar description of deep convective clouds. Our analysis shows that most of the deep convection occurs over the Bay of Bengal and central northeast India. Very deep convection over the Tibetan plateau is comparatively weak, and may play only a secondary role in troposphere-to-stratosphere transport. The deep convection over the Indian monsoon region is most frequent in July/August, but the very highest convection (coldest tops, penetrating well into the TTL) occurs in May/June. Large variability in convection reaching the TTL is due to monsoon break/active periods. During the monsoon break period, deep convection reaching the TTL is almost entirely absent in the western part of the study area (i.e. 60 E–75 E), while the distribution over the Bay of Bengal and the Tibetan Plateau is less affected. Although the active conditions occur less frequently than the break conditions, they may have a larger bearing on the composition of the TTL within the monsoonal anticyclone, and tracer transport into the stratosphere because of deep convection occurring over anthropogenically more polluted regions.

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