Pankaj Kumar

Indian Institute of Science Education and Research Bhopal | IISER · Department of Earth and Environmental Sciences

Precipitation downscaling is recognized as a challenging problem due to its stochasticity and highly skewed distribution. The downscaling of coarse resolution global climate data is most important in the context of regional-scale climate change impact research and assessments. Image super-resolution is a well-established domain in deep learning, wh...

Deep learning methods have emerged as a potential alternative for the complex problem of climate data downscaling. Precipitation downscaling is challenging due to its stochasticity, skewness, and sparse extreme values. Also, the extreme values are essential to preserve during downscaling and extrapolating future climate projections, as they serve a...

With an increasing focus on improving localized understanding of weather and climate phenomena and the computation cost involved in high-resolution modelling, spatial downscaling of data has proven to be a viable alternative method to obtain high-resolution climate data. Historically, several statistical and dynamical downscaling techniques have be...

In this study, a future projection of marine cold spells (MCSs) over the tropical Indian Ocean is made using a fully coupled regional Earth system model, namely ROM, under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. In both RCPs, the future MCS properties have been estimated across three distinct time intervals: the near fu...

Western disturbances (WDs) are upper-tropospheric mid-latitude synoptic systems propagating eastward along the subtropical westerly jet stream. They are capable of causing extreme precipitation events and have strengthened their impact over the Karakoram part of the Himalayas in recent decades. They play a crucial role in the sustenance of the “Kar...

Glaciers, in general, are sensitive to changes in the climate but Himalayan glaciers, in particular, are highly affected by climate change. Mass balance (MB) of glaciers is one of the important parameters to examine the response of glaciers to climate variability and change. The study of mass balance sensitivity (MBS) due to climate perturbations f...

To expedite regional-scale climate change impact research and assessments, the downscaling of climate data is a crucial prerequisite. Image super-resolution, which is analogous to gridded data downscaling, is the concept of improving the pixel quality of images using deep learning techniques. In this study, the performance of a Super-Resolution Gen...

This study employed a regional earth system model, namely ROM over the CORDEX-SA domain, to investigate the future changes in the Marine heatwaves (MHWs) with respect to the historical baseline period (1976-2005) in the three time-slices, explicitly, near future (NRF; 2010–2039), middle future (MDF;2040-2069), and far future (FRF; 2070–2099) under...

Understanding the trends and variations in precipitation patterns under changing climate scenarios is essential for better preparation, adaptation, and mitigation. Usually, the global climate model simulations are available at coarse resolution, which is unsuitable for regional applications. Further downscaling using dynamic/statistical methods and...

This study examines the future climate change in the South Asia region during 2070–2099 with respect to the historical period (1975–2004) under RCP8.5 scenario using a high-resolution regional earth system model. We found substantial changes in the key climatic parameters over the South Asia region including ocean biological productivity, however,...

Western disturbances (WDs) are upper-tropospheric synoptic-scale cyclonic storms that travel eastwards embedded in the subtropical westerly jet stream. They are of veritable significance to the sustenance of the population in the north and northwest regions of the Indian subcontinent and are often harbingers of extreme precipitation events during t...

Climate change is leading to alterations in the dynamic climate systems worldwide. The Indian Summer Monsoon (ISM) is one such climate system that supports more than a billion population and drives the Indian economy. The ISM is governed by intra-annual to inter-decadal variabilities. However, anthropogenic climate change is inducing unprecedented...

Northeast Monsoon of South Asia

A regional earth system model (ROM) was used to examine the projected change in the precipitation extremes (PEs) and associated dynamical and thermodynamical processes over India during the Indian summer monsoon (ISM). In this regard, PEs are computed for India, its six homogeneous regions and subregions the Western Ghats (WG) and central India (CI...

Downscaling of gridded climate data is an essential requirement to expedite climate change-related studies at the regional and local scales. The two traditional methods for downscaling gridded data are statistical and dynamical methods. Dynamic downscaling uses a high-resolution regional model across a small area, which makes it physically consiste...

Downscaling of gridded climate data is an essential requirement for regional and local scale studies. Statistical and dynamical methods are the two conventional methods for downscaling. The suitability of Artificial Intelligence / Machine Learning / Deep Learning based image super-resolution techniques for the downscaling of gridded climate data is...

To examine the present and future mean variability of the Indian Summer Monsoon onset over Kerala, a high-resolution regional atmosphere-ocean coupled model (ROM) is deployed over the Coordinated Regional climate Downscaling Experiment (CORDEX) South Asia region. The model demonstrated its performance in simulating the onset and accompanying dynami...

This study examines the future climate change in the South Asia region during 2070–2099 with respect to the historical period (1975–2004) under RCP8.5 scenario using a high-resolution regional earth system model. We found substantial changes in the key climatic parameters over the South Asia region including ocean biological productivity, however,...

This study aims to provide a comprehensive and balanced assessment of recent scientific studies on the evolution, temporal variability and prediction of tropical cyclones (TCs), focusing on the North Indian Ocean (NIO). The involvement of earth’s components in TC genesis and intensification has been elaborated in a confined way. The advancement of...

Velocity of climate change (VoCC), also known as climate velocity, has been widely used as a climate change metric to inform the past and projected impacts of climate change on biodiversity globally. It is a generalized climate-landscape metric that does not involve any biological assumptions and is beneficial for regions with a lack of extensive s...

Indian summer monsoon (ISM) and its associated variabilities have a pronounced impact on the lives and livelihood of millions of inhabitants of the Indian sub-continent. This study made an effort to diagnose the changes in precipitation events and their plausible mechanisms during active and break spells of Indian summer that crop up during the pea...

This study highlights the land use/land cover change, and its implications on the long-term changes in various hydrometeorological parameters in India during 2001–2018. The study exhibited a decrease in grassland (15.1%), barren land (10.2%), and shrubland (9.5%) in contrast to an increase in deciduous broadleaf forest cover (27.4%) and croplands (...

Drought is a recurring hydroclimatic extreme whose frequency and intensity have increased over India in recent decades, with a detrimental effect on regional water resources. This study addresses the spatiotemporal variability of drought and its plausible mechanism over India from 1951 to 2018. Firstly, six drought‐homogeneous regions are adequatel...

Understanding climate variability requires good quality high resolution spatially and temporally varying ocean fields due to its decisive role in regulating the region's climate, including the Indian summer monsoon. In this regard, we employed a new high‐resolution regional earth system model (RESM), namely ROM over CORDEX South Asia. We demonstrat...

The Himalaya plays a vital role in regulating the freshwater availability for nearly a billion people living in the Indus, Ganga, and Brahmaputra River basins. Due to climate change and constantly evolving human-hydrosphere interactions, including land use/cover changes, groundwater extraction, reservoir or dam construction, water availability has...

The tropical cyclones (TCs) are most likely to increase over the North Indian Ocean (NIO) due to rapid heating in a warming climate. However, past studies have made contrasting statements while analyzing different study periods. This study examines the variability of TC’s characteristics such as severity, frequency, and longevity over the Arabian S...

Tropical cyclones (TC) predictions are crucial and of significant scientific and socio-economic interest. To improve the TC's simulation, this study aimed to use the Weather Research and Forecasting (WRF) model to assimilate satellite radiances and surface and upper-air conventional observations cyclically at the intervals of 6 h. The predictive sk...

An effort is made to implement a Regional Earth System Model (RESM) over the CORDEX-SA domain to demonstrate its skill in simulating the Indian summer monsoon characteristics. RESM was simulated on climate mode, 1980-2014, and showed good resemblance to observation in simulating mean precipitation, its variability (intraseasonal to interannual), ex...

In contrast to the general retreat of glaciers across the globe, the glaciers of the Karakoram (KR) region of Karakoram-Himalayas (KH) have displayed an anomalous divergent response, with some glaciers remaining either stable or surging. This phenomenon is known as the "Karakoram Anomaly." Although many factors are reported to have control over it...

This study using a high resolution (~ 25 km) regional coupled earth system model ROM (REMO-OASIS-MPIOM), addresses the future projections of heatwave characteristics (frequency, duration, and severity) and associated dynamics over India for the AMJ (April–May–June) season. The near-surface maximum temperature (Tmax) is used to identify the prominen...

We investigate the effect of variable marine biogeochemical light absorption on Indian Ocean sea surface temperature (SST) and how this affects the South Asian climate. In twin experiments with a regional Earth system model, we found that the average SST is lower over most of the domain when variable marine biogeochemical light absorption is taken...

An accurate representation of the Indian Ocean Dipole (IOD) is crucial for the reliable projection of Indian summer monsoon rainfall, making it necessary to improve the understanding of the response of the IOD in the warming climate. For the first time, a high-resolution regional earth system model (RESM) over the CORDEX-SA domain is used to invest...

The global retreat in glaciers is considered to be one of the critical indicators of climate change. However, the glaciers of the Karakoram (KR) region of Karakoram-Himalayas (KH) stand out because of their divergent response, displaying a surge as opposed to glaciers in other regions. This phenomenon is known as the “Karakoram Anomaly.” Although m...

A new high-resolution Regional Earth System Model, namely ROM, has been implemented over CORDEX-SA towards examining the impact of air–sea coupling on the Indian summer monsoon characteristics. ROM's simulated mean ISM rainfall and associated dynamical and thermodynamical processes, including the representation of northward and eastward propagating...

Tropical cyclones (TCs) are among the catastrophic natural hazards over the North Indian Ocean (NIO), and they are expected to become more frequent in the upcoming years. TCs occur primarily in the pre-monsoon (April–June) and post-monsoon (October–December) seasons, wreaking havoc on South Asian regions. For reliable alerts and disaster warnings a...

An effort is made to implement a regional earth system model (RESM); ROM, over CORDEX-South Asia (SA). The added value of RESM is assessed for mean precipitation, its variability (intraseasonal to interannual), extremes, and associated processes. In this regard, ROM’s fields are compared with the respective fields of its standalone version (REMO),...

Two experiments with a regional Earth System Model (ESM) are performed. We discovered that in a simulation where light attenuation is calculated taking into account the water temperature–phytoplankton feedback the average sea surface temperature (SST) is lower over most of the tropical Indian ocean in comparison with the reference experiment in whi...

Drought is a recurring insidious hydro-climatic extreme that adversely affects agriculture growth and leading to long-lasting severe impacts on regional water resources and ecosystem. A comprehensive assessment of drought is possible in a sophisticated manner by advanced climate modelling approaches that enhance process understanding and improve fu...

In this study, the stochastic kinetic energy backscatter scheme ( based 30 member ensemble variational data assimilation method has been adopted to improve the track, intensity and rainfall prediction of the north Indian Ocean tropical cyclones. Two cases, a very severe cyclonic storm ( Yaas 23 27 May 2021 and VSCS Titli 8 13 October 2018 formed ov...

Anthropogenic climate change has adversely affected the global biodiversity and is driving their range shifts polewards, to higher elevations on the land and deeper in the oceans. These changes result from the interactions between the climate drivers and non-climatic factors. The threat is exacerbated due to the synergistic effects of climate chang...

This study examines different precipitation events (PEs) for 1951–2015 using 0.25°×0.25° India Meteorological Department data and diagnoses their associated dynamical and thermodynamical processes during the summer monsoon season over India using ERA5 reanalysis. Our results reveal a significant decreasing trend of mean precipitation, rain event da...

An effort is made to investigate the tropical cyclone (TC) variability over the Bay of Bengal in the warming climate scenario during the satellite era (1979–2018). In this study, the authors investigate interannual variations in the overall capacity of the Bay of Bengal (BoB) basin in the post‐monsoon season to produce either intense or moderate TC...

We investigate the effect of variable marine biogeochemical light absorption on Indian Ocean sea surface temperature (SST) and how this affects the South Asian climate. In twin experiments with a regional Earth System Model, we found that the average SST is lower over most of the domain when variable marine biogeochemical light absorption is taken...

This study provides an evaluation of the past, present, and future spatiotemporal variability of droughts in the Bundelkhand region of central India. The assessment has been made by analyzing the existing (1951–2018) drought dynamics with gridded observational and reanalysis datasets. The future projection is presented using a multi-model ensemble...

The heatwave is a disastrous hazard having significant impacts on health and society. This study analyses the heatwave hazards and risk for India's current and future scenarios using socioeconomic vulnerability and temperature datasets during the summer (April–June) season. The Census of India (CoI) 2011 datasets were considered to assess current v...

Drought frequency and intensity have increased in recent decades and are expected to escalate in future under the changing climate scenario. However, a wide range of uncertainty exists regarding the risk, variability and severity of the drought. This study evaluates the future drought and associated uncertainty over homogeneous regions of India usi...

For the first time for CORDEX-South Asia, a high-resolution regional earth system model (ROM) is adopted to assess the impact of horizontal resolution (0.22° and 0.11°) in simulating the Indian summer monsoon rainfall (ISMR) and the underlying spatiotemporal variability. ROM at both resolutions bears a close resemblance to observations in simulatin...

Climate change has impacted the nature and the severity of extreme temperatures over India in the recent past. In this study, the characterization in nature and change of hot season (March–May) temperatures across India's various geographical regions have been analysed over the last 69 years. Using canonical correlation analysis (CCA), we elucidate...

Skilful seasonal prediction of tropical cyclones (TCs) can help storm preparedness and mitigate their destructive impacts and is thus of profound socio-economic value. The cumulus convection and the planetary boundary layer (PBL) processes play a significant role in forming and intensifying TCs. Five combinations of physical parameterization scheme...

Climate change has a detrimental impact on human health due to increasing temperature extremes. It is undoubtedly true over India, where in recent decades a rise in the frequency and intensity of extreme events is witnessed. The present study primarily focuses on understanding the dynamics of the hot season over homogeneous regions of India. Using...

Hydrological extremes have increased in recent decades and are expected to escalate in the future. This led to global and regional water stress and drought hazards. Further down in the chain it impacts on farming, pollution, ecosystem, and socioeconomic conditions. A better understanding of both quantitative and qualitative assessment of drought un...

This paper examines the projected changes in rainfall in Southeast Asia (SEA) in the twenty-first century based on the multi-model simulations of the Southeast Asia Regional Climate Downscaling/Coordinated Regional Climate Downscaling Experiment–Southeast Asia (SEACLID/CORDEX–SEA). A total of 11 General Circulation Models (GCMs) have been downscale...

The air-sea interaction processes and their relation to Indian summer monsoon rainfall via dynamic and thermodynamic components are vital. The present study examined the two contrasting monsoon years 2016 (normal) and 2017 (below normal) and highlighted the significance of air-sea interaction in the understanding the rainfall over central India. We...

A regional Earth System Model has been implemented for the South Asia region. We investigate the effect of the marine biogeochemical feedback which affects the attenuation of the short-wave radiation upon the regional climate. In the experiment where the feedback is activated the average SST is lower over most of the domain. The greatest deviations...

Within the Coordinated Regional Climate Downscaling Experiment (CORDEX) framework, a high-resolution Regional Earth System Model (RESM) was used to understand the effects of various parameterizations of the attenuation of shortwave radiation (SWR) penetrating into the ocean. The RESM comprises of the Max Planck Institute Ocean Model and the Hamburg...

There are few studies dedicated to assessing the impact of biogeochemistry feedbacks on the climate change signal. In this study, we evaluate this impact in a future climate change scenario over the Indian subcontinent with the coupled regional model ROM in the Indian CORDEX area.In ROM a global ocean model (MPIOM) with regionally high horizontal r...

Glacier retreat is a key indicator of climate variability and change. Karakoram-Himalaya (KH) glaciers are the source of several perennial rivers protecting water security of a large fraction of the global population. The region is highly vulnerable to climate change impacts, hence the sensitivity of KH glaciers to regional microclimate, especially...

Heatwave, one of the most devastating natural hazards frequently referred to as 'silent killers' is governed by small as well as large scale physical and dynamical processes. Being a tropical country, India is exposed to such a hazard in summer (March-May). The present study deals with primary justification for the occurrence of heatwaves over Indi...

Indian natural forest has a high ecological significance as it holds much biodiversity and is primarily affected due to deforestation. The present study exhibits the forest cover change on Global Forest Non-Forest (FNF) data for India and greenness trend using MOD15A2H LAI product, which is the best product available till date. JAXA uses of SAR dat...

Glaciers in the Himalaya-Karakoram (HK) are critical for ensuring water-security of a large fraction of world’s population that is vulnerable to climate impacts. However, the sensitivity of HK glaciers to changes in meteorological forcing remains largely unknown. We analyzed modelled interannual variability of mass balance (MB) that is validated ag...

A complete simulation of glacier climate interaction over South-Asia is done for the period 1989-2016. • Model is largely able to capture the precipitation variability both spatially & temporally well over KH region. • Over the highly complex and data sparse region, the simulated mass balance largely agrees with observations including the positive...

Meltwater runoff in the catchment area containing Chhota Shigri glacier (Western Himalaya) is simulated for the period 1951–2099. The applied mass-balance model is forced by downscaled products from four regional climate models with different horizontal resolution. For the future climate scenarios we use high resolution time series of 5 km grid spa...

Glacier mass balance and runoff are simulated from 1955 to 2014 for the catchment (46% glacier cover) containing Chhota Shigri Glacier (Western Himalaya) using gridded data from three regional climate models: (1) the Rossby Centre regional atmospheric climate model v.4 (RCA4); (2) the REgional atmosphere MOdel (REMO); and (3) the Weather Research a...

Drought is long term slowly occurring disaster initiated as deficit of precipitation and high evapotranspiration. Exponential population growth has leads to increased agriculture water demands manifold especially over developing countries. Several studies shows that drought reoccurrence intensity and frequency has increased over India in last decad...

Here we present results of a workshop designed to bring together stakeholders from different states of the Indian side of Himalayan arc and an international group of climate scientists in order to discuss how climate change research for this region can be tailored towards the needs of local communities. The stakeholder workshop was jointly organize...

The Karakoram and the Himalayan mountain range (K-H) accommodate a large number of glaciers and are the major source of several perennial rivers downstream. To interactively describe to response of glaciers to climate change, a glacier parameterization scheme has been developed and implemented into the regional climate model REMO. The scheme simula...

A regional coupled atmosphere–ocean model is developed to study the monsoon climate over South Asia. Most of the climate models (both GCM and RCM) underestimate precipitation over South Asia, but overestimate precipitation over the Bay of Bengal and the equatorial Indian Ocean. These systematic differences between the models may be related to a fun...

In the present study, the influence of soil thermal characteristics (STC) on the simulated monsoon climate over south Asia is analyzed. The study was motivated by a common warm temperature bias over the plains of northern India that has been noticed in several global and regional climate models. To address this warm bias and its relation to STC, tw...

Using an ensemble of four high resolution (~25 km) regional climate models, this study analyses the future (2021–2050) spatial distribution of seasonal temperature and precipitation extremes in the Ganges river basin based on the SRES A1B emissions scenario. The model validation results (1989–2008) show that the models simulate seasonality and spat...

The Indian subcontinent faces a population increase from 1.6billion in 2000 towards 2billion around 2050. Therefore, expansion of agricultural area combined with increases in productivity will be necessary to produce the food needed in the future. However, with pressure on water resources already being high, and potential effects of climate change...

Global and regional climate model simulations are frequently used for regional climate change assessments and in climate impact modeling studies. To reflect the inherent and methodological uncertainties in climate modeling, the assessment of regional climate change requires ensemble simulations from different global and regional climate model combi...

Over 800 million people depend on glacier melt water runoff throughout the Hindu-Kush and Himalaya (HKH) region. The region, also called as "Water tower of Asia", is the location of several major rivers basins, like Ganges, Brahmaputra, and Indus etc. Glaciers in the HKH region are the primary source of water for the perennial rivers. Previous stud...

A.E.); stefan.hagemann@zmaw.de (S.H.); pankaj.kumar@zmaw.de (P.K.); diana.rechid@zmaw.de (D.R.); armelle.remedio@zmaw.de (A.R.R.); kevin.sieck@zmaw.de (K.S.); claas.teichmann@zmaw.de (C.T.); christof.wilhelm@zmaw.de (C.W.) Abstract: The transferability of the regional climate model REMO with a standard setup over different regions of the world has...

Climate change is expected to have a profound impact on the availability of water in the Ganga basin. Combined changes in glacier melt and monsoon precipitation will affect the total amount of water available. Increasing greenhouse gases are likely to lead to intensification of the water cycle, causing an increase in extreme events, especially drou...

Adaptation is increasingly important for regions around the world where large changes in climate could have an impact on populations and industry. The Brahmaputra-Ganges catchments have a large population, a main industry of agriculture and a growing hydro-power industry, making the region susceptible to changes in the Indian Summer Monsoon, annual...

This study presents the possible regional climate change over SA with a focus over India as simulated by three very-high-resolution regional climate models. The models are driven by the same lateral boundary conditions from two global models (ECHAM5-MPIOM and HadCM3) under the IPCC AR4 SRES A1B scenario at horizontal resolution of ~25km, except one...

An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector adaptation measures and policies might be adopted a...

The ability of four regional climate models (RCMs) to represent the Indian monsoon was verified in a consistent framework for the period 1981-2000 using the 45-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) as lateral boundary forcing data. During the monsoon period, the RCMs are able to capture the spatial distr...

In order to investigate impacts of future climate change on a regional scale there is a rising need for high-resolution climate information in all parts of the globe. However, so far for many regions in the world, only coarse resolution global general circulation model output is available that often does not capture specific regional climate charac...