Tracing the convective sources of air at tropical tropopause during the active and break phases of Indian summer monsoon

Sivan, C.; Kottayil, Ajil; Legras, Bernard; Bucci, Silvia; Mohanakumar, K.; Satheesan, K.

doi:10.1007/s00382-022-06238-9

Cited by 3 publications

(3 citation statements)

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“…The 200 hPa is also a level where Asian monsoon anticyclone (AMA) is persistent during monsoon season. During boreal summer, AMA can extend from the upper troposphere to the lower stratosphere, and the northern and southern flanks of AMA are dominated by subtropical westerly jet and easterly jet, respectively (Legras & Bucci, 2020; Sivan et al, 2022; Wei et al, 2019). The mechanism for the maintenance of AMA is proposed to be diabatic heating over the high land and monsoon regions (Liu et al, 2001; Ortega et al, 2017).…”

Section: Resultsmentioning

confidence: 99%

“…To reiterate this, the potential vorticity at 200 hPa is examined and is shown in Figure 10. PV is often used to determine the strength of AMA and the low values of PV (less than 1.5 PVU) represent the divergence forcing of the convective outflow within the anticyclone (Sivan et al, 2022). The upper‐level divergence associated with convective outflow leads to an expansion in the area of low PV (Garny & Randel, 2013).…”

Section: Resultsmentioning

confidence: 99%

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Influence of monsoon extreme rainfall on the distribution of upper tropospheric humidity

Devika,

Kottayil,

Koovekkallu

et al. 2023

Intl Journal of Climatology

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This study focuses on the changes in the upper tropospheric humidity (UTH) associated with two different extreme precipitation conditions for the period 2000–2019 over the Indian summer monsoon region. The analysis embodies UTH datasets derived from microwave sounders on‐board NOAA and MetOp‐A polar‐orbiting satellites. The circulation characteristics in the upper troposphere are studied using the high‐resolution ERA5 reanalysis data. The analysis of UTH variability over the Indian region shows a unique positive (negative) UTH anomaly patch extending from northwestern regions of India to the northern Arabian Sea for the enhanced (deficient) rainfall days over central India during the southwest monsoon period. The investigation reveals that deep convection alone does not impact the UTH variability. Rather the circulation in the upper troposphere also plays a crucial role in UTH distribution. The dynamics in the upper troposphere cause large‐scale dispersal of both wet and dry air in the upper troposphere, which is linked to the strengthening/weakening of Asian monsoon anticyclone. The study indicates that monsoon extremes exhibit a distinct moisture distribution pattern in the upper troposphere, influenced by upper‐level dynamics, which are associated with the intensity of the Asian monsoon anticyclone.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Influence of monsoon extreme rainfall on the distribution of upper tropospheric humidity

Devika,

Kottayil,

Koovekkallu

et al. 2023

Intl Journal of Climatology

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“…The quasi-biweekly oscillation is a seasonal characteristic of the SAH [51], leading to changes in the atmosphere's thermal structure and circulation field [52,53]. Previous studies have primarily focused on its interactions with the summer monsoon and precipitation patterns [54][55][56][57][58][59]. However, how this powerful circulation system will affect dust activity has not been clearly concluded.…”

Section: Introductionmentioning

confidence: 99%

Summer Extreme Dust Activity in the Taklimakan Desert Regulated by the South Asian High

Wang

Han

et al. 2023

Remote Sensing

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Summer dust aerosol in the Taklimakan Desert (TD) affects not only the albedo of the snow and ice sheets on the Tibetan Plateau (TP) but also air quality and precipitation in the downstream areas. In this study, the summer extreme dust activity in the TD was jointly investigated by using satellite observations and MERRA-2 reanalysis datasets and divided into two states: dust active period and dust inactive period. The horizontal and vertical distribution of summer dust during both the dust active and inactive periods, as derived from the MERRA-2 dataset, is consistent with satellite observations. By comparing the upper-level circulation and surface meteorological elements at two periods, we identify the South Asian High (SAH) as the dominant factor driving the extreme dust activity in the TD during summer. When the SAH is centered on the Iranian Plateau (IP), the dust aerosol in the TD exhibits increased activity and is lifted to higher altitudes due to significantly enhanced westerly winds, near-surface wind speed, and an ascending motion. Conversely, when the SAH is centered on the TP, the summer dust activity shows the opposite behavior. These new findings on the regulatory mechanism of the SAH on the summer dust activity in the TD are highly significant for understanding the occurrence and transport of summer Asian dust and its potential impact on heavy precipitation in the downstream areas.

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Role of deep convection and dynamics on the tracer distribution in the upper troposphere and lower stratosphere region during active and break phases of the Asian summer monsoon

Satheesh Chandran,

Sunilkumar

2023

Clim Dyn

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Tracing the convective sources of air at tropical tropopause during the active and break phases of Indian summer monsoon

Cited by 3 publications

References 50 publications

Influence of monsoon extreme rainfall on the distribution of upper tropospheric humidity

Influence of monsoon extreme rainfall on the distribution of upper tropospheric humidity

Summer Extreme Dust Activity in the Taklimakan Desert Regulated by the South Asian High

Role of deep convection and dynamics on the tracer distribution in the upper troposphere and lower stratosphere region during active and break phases of the Asian summer monsoon

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