scholarly journals The greening of Northwest Indian subcontinent and reduction of dust abundance resulting from Indian summer monsoon revival

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Qinjian Jin ◽  
Chien Wang
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent

Holocene climate variability and Indian Summer Monsoon: An overview

The Holocene ◽  
2020 ◽  
Vol 30 (5) ◽  
pp. 744-773 ◽  
Author(s):  
Upasana S Banerji ◽  
P Arulbalaji ◽  
D Padmalal
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
Ice Age ◽  
Interglacial Period ◽  
Northern Indian Ocean ◽  
The Holocene ◽  
Indian Landmass ◽  
Holocene Period

The response of the Indian Summer Monsoon (ISM) to forcing factors and climate variables has not yet fully explored, even though the ISM plays a pivotal role in the socio-economics of the Indian subcontinent and nearby areas. The ISM progression over Indian landmass is a manifestation of the Intertropical Convergence Zone (ITCZ) migration over the northern Indian Ocean and the Indian subcontinent. The recent anomalous behaviour of ISM raises the need for a better understanding of its spatio-temporal changes during the ongoing interglacial period termed as the Holocene period. The Holocene period has been classified further based on the globally observed abrupt climatic events at 8.2 and 4.2 ka. The 8.2 ka global cooling events have been recorded from northern Indian Ocean marine archives but limited records from the continental archives of the Indian landmass has demonstrated the 8.2 ka event. At the same time, the 4.2 ka dry climate has been endorsed by both marine as well as continental records and agrees with the global studies. During the ‘Little Ice Age’ (LIA), in the India subcontinent, wet conditions prevailed in the northern, central and western regions while a dry climate existed over the greater part of peninsular India. The present review offers an account of ISM signatures and possible mechanisms associated with the monsoon variability in the Indian subcontinent and the northern Indian Ocean during the Holocene period.

Seasonal prediction of Indian Summer Monsoon onset with machine learning

2021 ◽  
Author(s):  
Takahito Mitsui ◽  
Niklas Boers
Keyword(s):  
Time Scales ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Water Resource Management ◽  
Prediction Models ◽  
Indian Subcontinent ◽  
Weather Prediction ◽  
Seasonal Prediction ◽  
Onset Date ◽  
Summer Monsoon Onset

<p>The prediction of the onset date of the Indian Summer Monsoon (ISM) is crucial for effective agricultural planning and water resource management on the Indian subcontinent, with more than one billion inhabitants. Existing approaches focus on extended-range to subseasonal forecasts, i.e., provide skillful predictions of the ISM onset date at horizons of 10 to 60 days. Here we propose a method for ISM onset prediction and show that it has high forecast skill at longer, seasonal time scales. The method is based on recurrent neural networks and allows for ensemble forecasts to quantify uncertainties. Our approach outperforms state-of-the-art numerical weather prediction models at comparable or longer lead times. To our knowledge, there is no statistical forecasting approach at comparable, seasonal time scales. Our results suggest that predictability of the ISM onset emerges earlier than previously assumed.</p>

scholarly journals Snow-darkening versus direct radiative effects of mineral dust aerosol on the Indian summer monsoon onset: role of temperature change over dust sources

2019 ◽  
Vol 19 (3) ◽  
pp. 1605-1622 ◽  
Author(s):  
Zhengguo Shi ◽  
Xiaoning Xie ◽  
Xinzhou Li ◽  
Liu Yang ◽  
Xiaoxun Xie ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Central Asia ◽  
Black Carbon ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Radiative Forcing ◽  
Indian Monsoon ◽  
Indian Subcontinent ◽  
Direct Radiative Forcing

Abstract. Atmospheric absorptive aerosols exert complicated effects on the climate system, two of which are through their direct radiative forcing and snow-darkening forcing. Compared to black carbon, the snow-darkening effect of dust on climate has been scarcely explored till now. When depositing in snow, dust can reduce the albedo of snow by darkening it and increasing the snowmelt. In this study, the snow-darkening effect of dust, as well as the direct radiative effect, on the Indian summer monsoon are evaluated by atmospheric general circulation model experiments. The results show that the snow-darkening and direct radiative forcing of dust both have significant impacts on the onset of the Indian monsoon, but they are distinctly opposite. The snow-darkening effect of dust weakens the Indian monsoon precipitation during May and June, opposite to black carbon. The surface temperature over central Asia and the western Tibetan Plateau becomes warmer due to the dust-induced decrease in snow cover, which leads to a local low-level cyclonic anomaly as well as an anticyclonic anomaly over the Indian subcontinent and Arabian Sea. This circulation pattern allows air currents penetrating into the Indian subcontinent more from central Asia but less from the Indian Ocean. In contrast, the direct radiative forcing of dust warms the low troposphere over the Arabian Peninsula, which intensifies moisture convergence and precipitation over the Indian monsoon region. The upper tropospheric atmospheric circulation over Asia is also sensitive to both effects. Compared to previous studies which emphasized the temperature over the Tibetan Plateau, our results further highlight an important role of surface/low tropospheric temperature changes over dust source areas, which can also significantly modify the response of summer monsoon. Thus, links between the climatic impact of dust and complicated thermal conditions over Asia are of importance and need to be clarified accurately.

scholarly journals Airmass analysis of the processes driving the progression of the Indian summer monsoon

2020 ◽  
Author(s):  
Ambrogio Volonté ◽  
Andrew G. Turner ◽  
Arathy Menon
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea ◽  
Model Simulation ◽  
Indian Subcontinent ◽  
Limited Area ◽  
Lagrangian Analysis ◽  
Air Masses ◽  
Diabatic Processes ◽  
Northwest India

<p>The Indian summer monsoon is a vital source of water and a cause of severe impacts for more than a billion people in the Indian subcontinent. The INCOMPASS project investigates the mechanisms driving its onset and progression through an observational field campaign supplemented by high-resolution numerical simulations for the 2016 season using UK Met Office models. A 4.4 km resolution convection-permitting limited-area model simulation (driven at its boundaries by a daily-initialised global model) is used in this study, and verified against observations, along with short-lead-time operational global forecasts.</p><p>These data show that the monsoon progression towards northwest India in June 2016 is a non-steady process, modulated by the interaction between moist low-level southwesterly flow from the Arabian Sea and a northwesterly incursion of descending dry air from western and central Asia. The location and extent of these two flows are closely linked to mid-latitude dynamics, through the southward propagation of potential vorticity streamers and the associated formation of cyclonic circulations in the region where the two air masses interact. Particular focus is devoted to the use of Lagrangian trajectories to characterise the evolution of the airstreams and complement the Eulerian monsoon progression analysis. The trajectories confirm that the interaction of the two airstreams is a primary driver of the general moistening of the troposphere associated with monsoon progression. They also indicate the occurrence of local diabatic processes along the airstreams, such as turbulent mixing and local evaporation from the Arabian Sea, in addition to moisture transport from remote sources.</p><p>In summary, this combined Eulerian-Lagrangian analysis reveals the non-steady nature of monsoon progression towards northwest India. This process is driven by the interaction of different air masses and influenced by a synergy of factors on a variety of scales, such as mid-latitude dynamics, transient weather systems and local diabatic processes.</p><p>This work has recently been accepted for publication on the Quarterly Journal of the Royal Meteorological Society.</p>

Reconstructing Past Indian Summer Monsoon Productivity and Stratification During the Late Pliocene and Early Pleistocene

2020 ◽  
Author(s):  
Emmeline Gray ◽  
Pallavi Anand ◽  
Clara Bolton ◽  
Masafumi Murayama ◽  
Marcus Badger
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
Climatic Conditions ◽  
Automated System ◽  
Early Pleistocene ◽  
Geochemical Data ◽  
Global Monsoon ◽  
International Ocean Discovery Program ◽  
Instrumental Records

<p>The South Asian or Indian Summer Monsoon (ISM) brings seasonal winds and rains to the Indian subcontinent and affects billions of people.  It is likely that the global monsoon will strengthen in a 1.5 °C warming scenario (IPCC special report (2018)), however our ability to predict ISM behaviour in the future is restricted due to lack of understanding of its behaviour under varying climatic conditions before instrumental records began.  Thus, reconstructing the palaeo-monsoon using proxies gives insight into past and potentially future controls on the ISM.  We present new data covering the interval ~5 to ~2 million years ago (Ma), during the Pliocene and early Pleistocene when the long-term Cenozoic cooling trend culminated in intense northern hemisphere glaciations from 2.7 Ma.  At this time, global temperatures are suggested to have been 2-3 °C warmer than today and atmospheric CO<sub>2</sub> was over 400 ppm (similar to today). </p><p>This study focuses on sediments from Site U1443 ( 5°N, 90°E), drilled during International Ocean Discovery Program (IODP) Expedition 353 in the Bay of Bengal (BoB) for the Pliocene – early Pleistocene.  We present X-ray fluorescence (XRF)-derived bulk sediment geochemical data and suggest that erosional flux (terrigenous elements/total counts) as well as productivity (Br/Cl) varied in response to runoff strength, precipitation, and wind stress at the study site to reconstruct ISM variability.  Additionally, new nannofossil assemblage and morphometric data, collected using the automated system SYRACO, are used to reconstruct BoB stratification and productivity and thereby assess ISM dynamics.  A new benthic oxygen isotope-based age model will allow us to place the Site U1443 records into the context of existing climate and monsoon records and evaluate ISM response due to external and internal climate forcing factors.</p>

scholarly journals Contribution of Monthly and Regional Rainfall to the Strength of Indian Summer Monsoon

2016 ◽  
Vol 144 (9) ◽  
pp. 3037-3055 ◽  
Author(s):  
Yangxing Zheng ◽  
M. M. Ali ◽  
Mark A. Bourassa
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
India Meteorological Department ◽  
Central India ◽  
Northeast India ◽  
Summer Monsoon Rainfall ◽  
Rainfall Series ◽  
Seasonal Rainfall ◽  
Regional Rainfall

Indian summer monsoon rainfall (ISMR; June–September) has both temporal and spatial variability causing floods and droughts in different seasons and locations, leading to a strong or weak monsoon. Here, the authors present the contribution of all-India monthly, seasonal, and regional rainfall to the ISMR, with an emphasis on the strong and weak monsoons. Here, regional rainfall is restricted to the seasonal rainfall over four regions defined by the India Meteorological Department (IMD) primarily for the purpose of forecasting regional rainfall: northwest India (NWI), northeast India (NEI), central India (CI), and south peninsula India (SPIN). In this study, two rainfall datasets provided by IMD are used: 1) all-India monthly and seasonal (June–September) rainfall series for the entire Indian subcontinent as well as seasonal rainfall series for the four homogeneous regions for the period 1901–2013 and 2) the latest daily gridded rainfall data for the period 1951–2014, which is used for assessment at the extent to which the four regions are appropriate for the intended purpose. Rainfall during July–August contributes the most to the total seasonal rainfall, regardless of whether it is a strong or weak monsoon. Although NEI has the maximum area-weighted rainfall, its contribution is the least toward determining a strong or weak monsoon. It is the rainfall in the remaining three regions (NWI, CI, and SPIN) that controls whether an ISMR is strong or weak. Compared to monthly rainfall, regional rainfall dominates the strong or weak rainfall periods.

A Tripole Pattern of Summertime Rainfall and the Teleconnections Linking Northern China to the Indian Subcontinent

2019 ◽  
Vol 32 (12) ◽  
pp. 3637-3653 ◽  
Author(s):  
Jie Zhang ◽  
Haishan Chen ◽  
Siwen Zhao
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Moisture Transport ◽  
Asian Summer Monsoon ◽  
Indian Subcontinent ◽  
Atmospheric Stability ◽  
Summer Rainfall ◽  
Northern China ◽  
High Variability ◽  
The Tibetan Plateau

Abstract Because of the interactive margin between the East Asian summer monsoon and westerly circulation, summer rainfall in northern China (NC) exhibits high variability. By employing reanalysis data and geostationary satellite data from the Fengyun-2G (FY-2G) satellite and using the linear baroclinic model (LBM) and Hybrid Single-Particle Lagrangian Integrated Trajectory model, this study suggests a tripole pattern in summer rainfall over NC and the Indian subcontinent (IS) that is related to the Indian summer monsoon. The distributions of atmospheric circulation indicate three teleconnections: one is from the IS via the Indo-China Peninsula (ICP) and NC, enhancing the Pacific–Japan (PJ) pattern; another is from the IS via west-central Asia and NC, arousing a Eurasian wave pattern; and the third is an IS–TP–NC pattern via the Tibetan Plateau (TP). Those teleconnections modulate vorticity and atmospheric stability over NC. In addition, along with the circulation distribution related to those teleconnections, two pathways of moisture transport related to the IS rainfall are suggested, except for moisture transport via the Bay of Bengal: one is from the Indo-Pacific to NC due to enhancing cyclones over the Indo-Pacific and a PJ-like pattern; and another is from the IS to NC via the TP within the midtroposphere, which modulates midtroposphere moisture fluxes and atmospheric stability over NC. Both teleconnections and moisture transport result in anomalous rainfall over NC. This study reveals a new mechanism and pathway of the Indian summer monsoon impacting NC rainfall, possibly explaining the reason behind the high variability in NC rainfall.

Middle Holocene Indian summer monsoon variability and its impact on cultural changes in the Indian subcontinent

2021 ◽  
Vol 255 ◽  
pp. 106825
Author(s):  
Varsha Rawat ◽  
Suman Rawat ◽  
Priyeshu Srivastava ◽  
P.S. Negi ◽  
Muthusamy Prakasam ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
Cultural Changes ◽  
Middle Holocene ◽  
Monsoon Variability

scholarly journals Revisiting the Possible Links between the Quasi-Biennial Oscillation and the Indian Summer Monsoon Using NCEP R-2 and CMAP Fields

2007 ◽  
Vol 20 (5) ◽  
pp. 773-787 ◽  
Author(s):  
Chantal Claud ◽  
Pascal Terray
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
Rainfall Variability ◽  
Equatorial Indian Ocean ◽  
Boreal Winter ◽  
Convective Activity ◽  
Quasi Biennial Oscillation ◽  
Zonal Winds ◽  
Biennial Oscillation

Abstract In the past the stratospheric quasi-biennial oscillation (QBO) has sometimes been proposed to explain the tendency for the Indian summer monsoon (ISM) to alternate between strong and weak years. In this study, NCEP Reanalysis-2 (R-2) and Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) fields are statistically analyzed to assess the relationship between equatorial zonal winds in the stratosphere and ISM. In a first step, it is shown that zonal winds at 15 hPa during the preceding winter (January–February) are the best stratospheric predictor of the summer rainfall over the Indian subcontinent as a whole. This relationship mainly holds for August and September, or the late ISM. Surprisingly, the QBO pattern is not significantly associated with the rainfall variability during June–July or the early ISM. CMAP and NCEP R-2 fields corroborate these findings and show that westerly QBO years are associated with a deepening of the monsoon trough over the Gangetic plains and decreased convective activity in the eastern equatorial Indian region. However, further statistical analysis shows that the QBO–ISM link is complex since a westerly QBO phase at 15 hPa in boreal winter leads to a weaker monsoon surface circulation with, in particular, a weakening of the Somali jet at the beginning of the monsoon, but a much stronger circulation in September. At that time, the Tibetan high is reinforced, the tropical easterly jet at 200 hPa is stronger over India, and the local reversed Hadley circulation is also strengthened north of the equator. The mechanisms by which the QBO may affect ISM have been explored through, in particular, correlations between stratospheric winds and tropopause temperature and pressure fields. The results provide support for an out-of-phase behavior of convective activity between the Indian subcontinent and the equatorial Indian Ocean induced by the QBO phase, especially during the late ISM. During a westerly QBO phase, convective activity is, in September, enhanced over India, which brings higher precipitation, compared to the east phase. This work also suggests that the winter QBO at 15 hPa could have some skill in foreshadowing the late ISM.

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