The Role of Boundary Layer Height in India on Transboundary Pollutions to the Tibetan Plateau

2022 ◽  
Author(s):  
Yu Chen ◽  
Siyu Chen ◽  
Dan Zhao ◽  
Jixiang Li ◽  
Hongru Bi ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tibetan Plateau ◽  
The Tibetan Plateau ◽  
Layer Height ◽  
Boundary Layer Height

scholarly journals Diurnal and seasonal variation of planetary boundary layer height over East Asia and its climatic change as seen in the ERA-5 reanalysis data

2022 ◽  
Vol 4 (2) ◽  
Author(s):  
Kwang-Yul Kim
Keyword(s):  
Boundary Layer ◽  
East Asia ◽  
Sensible Heat Flux ◽  
Reanalysis Data ◽  
Minor Role ◽  
The Tibetan Plateau ◽  
Regional Warming ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Continental Area

AbstractThe diurnal/seasonal structure of the boundary layer height (BLH) is investigated over East Asia by using the hourly synoptic monthly ERA5 reanalysis variables from 1979 to 2019. Sensible heat flux (SHF) is the major factor in the temporal and spatial variation of the BLH. Although BLH, in general, is positively correlated with SHF throughout the year, BLH-SHF relationship varies significantly based on the surface type, latitude and time of the year. Analysis also reveals that stability is an important parameter controlling the diurnal maximum BLH. The growth of BLH is strongly limited by the presence of a stable layer. On the other hand, BLH increases abruptly in the presence of a weakly stratified residual layer. In addition, regional warming tends to increase the BLH in the mid- to high-latitude continental area. In the low-latitude continental area, the sign of anomalous SHF varies seasonally and regionally. Stability plays only a minor role in the BLH change except over the Tibetan Plateau, where the increased stability at the top of boundary layer due to warming reduces BLH rather significantly.

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 Diurnal and Seasonal Variation of Planetary Boundary Layer Height  over East Asia and Its Climatic Change as Seen in the ERA-5 Reanalysis Data

2021 ◽  
Author(s):  
Kwang-Yul Kim
Keyword(s):  
Boundary Layer ◽  
East Asia ◽  
Sensible Heat Flux ◽  
Reanalysis Data ◽  
Minor Role ◽  
The Tibetan Plateau ◽  
Regional Warming ◽  
Layer Height ◽  
Boundary Layer Height ◽  
Continental Area

Abstract The diurnal/seasonal structure of the boundary layer height (BLH) is investigated over East Asia by using the hourly synoptic monthly ERA5 reanalysis variables from 1979–2019. Sensible heat flux (SHF) is the major factor in the temporal and spatial variation of the BLH. Although BLH, in general, is positively correlated with SHF throughout the year, BLH-SHF relationship varies significantly based on the surface type, latitude and time of the year. Analysis also reveals that stability is an important parameter controlling the diurnal maximum BLH. The growth of BLH is strongly limited by the presence of a stable layer. On the other hand, BLH increases abruptly in the presence of a weakly stratified residual layer. In addition, regional warming tends to increase the BLH in the mid- to high-latitude continental area. In the low-latitude continental area, the sign of SHF differs seasonally and regionally. Stability plays only a minor role in the BLH change except over the Tibetan Plateau, where the increased stability at the top of boundary layer due to warming reduces BLH rather significantly.

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

2014 ◽  
Vol 14 (4) ◽  
pp. 2055-2070 ◽  
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 and 20 August 2012 to understand the role of convection in rapidly transporting boundary layer air into the ULAC. 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 a majority of them crossing the boundary layer between 1600 and 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.

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