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 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 First Measurement of Atmospheric Mercury Species in Qomolangma Nature Preserve, Tibetan Plateau, and Evidence of Transboundary Pollutant Invasion

2018 ◽  
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 ◽  
North India ◽  
Mercury Species ◽  
The Tibetan Plateau ◽  
Air Masses ◽  
Nature Preserve

Abstract. Located in the world’s ‘Third Pole’ and a remote region connecting the Indian Ocean 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 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 GOM and PBM concentrations, decreasing from 35.2±18.7 to 19.1±11.0 pg m−3 and from 30.5±12.6 to 24.7±19.9 pg m−3, respectively. A unique daily pattern of GEM concentration in QNNP was observed, with a peak value before sunrise and a low value at noon. Unexpectedly, GOM concentrations (with a mean value of 21.3±13.5 pg m−3) in this region were considerably higher than the values in other clean or even polluted regions. A cluster analysis indicated that the air masses transported to QNNP changed significantly at different stages of the monsoon, and the major potential Hg sources shifted from north India and west Nepal to east Nepal and Bangladesh. With large coverage of glacier in QNNP, local glacier winds could enforce the transboundary transport of pollutants and transport the polluted air masses to the Tibetan Plateau. It should be noted that the atmospheric Hg concentrations in QNNP are higher than the reported values in some background regions, which addresses the need for a more specific identification of Hg sources in QNNP and the importance of international cooperation for global Hg controls.

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.

Modulation of coupled modes of Tibetan Plateau heating and Indian Summer Monsoon on summer rainfall over Central Asia

2021 ◽  
pp. 1-54
Keyword(s):  
Water Vapor ◽  
Tibetan Plateau ◽  
Central Asia ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Diabatic Heating ◽  
Summer Rainfall ◽  
Hadley Cell ◽  
Vapor Transport ◽  
Water Vapor Transport

Abstract It has been suggested that summer rainfall over Central Asia (CA) is significantly correlated with the summer thermal distribution of the Tibetan Plateau (TP) and the Indian summer monsoon (ISM). However, relatively few studies have investigated their synergistic effects of different distribution. This study documents the significant correlations between precipitation in CA and the diabatic heating of TP and the ISM based on the results of statistical analysis and numerical simulation. Precipitation in CA is is dominated by two water vapor transport branches from the south which are related to the two primary modes of anomalous diabatic heating distribution related to the TP and ISM precipitation, that is, the “+-” dipole mode in the southeastern TP and the Indian subcontinent (IS), and the “+-+” tripole mode in the southeastern TP, the IS, and southern India. Both modes exhibit obvious mid-latitude Silk Road pattern (SRP) wave trains with cyclone anomalies over CA, but with different transient and stationary eddies over south Asia. The different locations of anomalous anticyclones over India govern two water vapor transport branches to CA, which are from the Arabian Sea and the Bay of Bengal. The water vapor flux climbs while being transported northward and can be transported to CA with the cooperation of cyclonic circulation. The convergent water vapor and ascending motion caused by cyclonic anomalies favor the precipitation in CA. Further analysis corroborates the negative South Indian Ocean Dipole (NSIOD) in February could affect the tripole mode distribution of TP heating and ISM via the atmospheric circulation, water vapor transport and an anomalous Hadley cell circulation. The results indicate a reliable prediction reference for precipitation in CA.

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 Using a WRF simulation to examine regions where convection impacts the Asian summer monsoon anticyclone

2013 ◽  
Vol 13 (9) ◽  
pp. 24809-24853
Author(s):  
N. K. Heath ◽  
H. E. Fuelberg
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Satellite Observations ◽  
The Tibetan Plateau ◽  
Asian Summer ◽  
Upper Level

Abstract. The Asian summer monsoon is a prominent feature of the global circulation that is associated with an upper-level anticyclone (ULAC) that stands out vividly in satellite observations of trace gases. The ULAC also is an important region of troposphere-to-stratosphere transport. We ran the Weather Research and Forecasting (WRF) model at convective-permitting scales (4 km grid spacing) between 10–20 August 2012 to understand the role of convection in transporting boundary layer air into the upper-level anticyclone. Such high-resolution modeling of the Asian ULAC previously has not been documented in the literature. Comparison of our WRF simulation with reanalysis and satellite observations showed that WRF simulated the atmosphere sufficiently well to be used to study convective transport into the ULAC. A back-trajectory analysis based on hourly WRF output showed that > 90% of convectively influenced parcels reaching the ULAC came from the Tibetan Plateau (TP) and the southern slope (SS) of the Himalayas. A distinct diurnal cycle is seen in the convective trajectories, with their greatest impact occurring between 1600–2300 local solar time. This finding highlights the role of "everyday" diurnal convection in transporting boundary layer air into the ULAC. WRF output at 15 min intervals was produced for 16 August to examine the convection in greater detail. This high-temporal output revealed that the weakest convection in the study area occurred over the TP. However, because the TP is at 3000–5000 m a.m.s.l., its convection does not have to be as strong to reach the ULAC as in lower altitude regions. In addition, because the TP's elevated heat source is a major cause of the ULAC, we propose that convection over the TP and the neighboring SS is ideally situated geographically to impact the ULAC. The vertical mass flux of water vapor into the ULAC also was calculated. Results show that the TP and SS regions dominate other Asian regions in transporting moisture vertically into the ULAC. Because convection reaching the ULAC is more widespread over the TP than nearby, we propose that the abundant convection partially explains the TP's dominant water vapor fluxes. In addition, greater outgoing longwave radiation reaches the upper levels of the TP due to its elevated terrain. This creates a warmer ambient upper level environment, allowing parcels with greater saturation mixing ratios to enter the ULAC. Lakes in the Tibetan Plateau are shown to provide favorable conditions for deep convection during the night.

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.

Sign in / Sign up

Export Citation Format

Share Document