Abstract:
Well-informed decision-making is an integral part of impact-based forecasting (IBF), especially in the case of extreme rainfall events (EREs). Generally, the IBFs which are based on forecasts alone are not sufficient to completely mitigate the potential impacts. Including the information of local vulnerability in the decision-making process is crucial to enhance the quality of decision-making, and hence, offer better communication of IBFs. My talk revolves around a decision-making experiment which explores the different combinations of forecast-vulnerability information. The basic idea is to (1) improve the crisis decision-making process by making it more well-informed and (2) better anticipate, communicate and mitigate the impacts associated with EREs. The setup is a realistic decision-making game in which players act as crisis decision-makers during an ERE. The players are provided decision-choices which they choose to opt, or otherwise, based on the different combinations of forecast-vulnerability information provided to them. For each decision, the player is allotted an approval score which is positive if the decision is correct and negative otherwise. The winning strategy is to make decisions such that the overall approval score remains positive. The game is played with different groups of students, hydrologists, decision-makers, researchers etc. The decision-making game discusses the challenges of optimum decision-making and effective communication of IBFs to local stakeholders.

Abstract:
Radon, the heaviest of all naturally-occurring noble gases, has received the most attention among all noble gases over the past 5 decades, as it is the single major contributor to the ionizing radiation and is the second most frequent cause of lung cancer after smoking. Radon (222Rn, half-life, T1/2 = 3.82 days) and its progeny (210Po, T1/2 = 138.4 days and 210Pb, T1/2 = 22.3 years) in the atmosphere have been widely utilized as powerful tracers to quantify atmospheric processes including:

1. i) source tracking and transport (within and between troposphere and stratosphere) time scale of air masses, stability and vertical movement of air masses;
2. ii) scavenging rate constants and residence times of aerosols;
3. iii) deposition velocities and washout ratios of aerosols;
4. iv)sources of continental dust in an air mass; and
5. v) processes of attachment of metal ions to atmospheric aerosols.

Abstract:
Space Weather refers to the physical conditions within the space environment which includes the conditions on the sun and in the space between the sun and the earth. Adverse Space Weather conditions can cause disruption of satellite operations, communications, navigation, and power grids, leading to several of socio-economic losses. This is a harsh reality we have to live with in the present times as we are increasingly dependent on the satellite systems and sub-systems in our social life. Global scientific community has recognized the severe magnitude of the issue and various methods and approaches are being attempted to predict the adverse Space Weather conditions. During this talk several components of the sun-earth system that either participate in, or are affected by the Space Weather will be introduced. The adverse impacts on the ground and on the equipment placed at different latitudes on the earth and at different heights (within the purview of the space environment) will be discussed. Presently, there are no reliable methods to unambiguously predict or forecast the space weather effects. However, several research groups across the globe are carrying out efforts to understand the processes/mechanisms by which the effects between the sun and the earth are communicated. This is a major research issue of current interest and has attracted the attention of both scientists and policy makers. The present plans that are underway in India with regard to future space missions for space weather studies will also be touched upon so that one can appreciate the magnitude of the efforts being carried out to address important and highly pertinent issue.

Abstract:
The complexity of the cloud system,due to the wide range of scales, makes it challenging to study cloud phenomena occurring at the micro-scale. Generally, the small-scale processes involved in modelling cloud phenomena, such as droplet and aerosol dynamics and turbulent properties at the Kolmogorov scale, are not fully captured by numerical models. In addition, the cloud's large-scale radiative characteristics and effect on the climate system can be affected by entrainment and mixing, which can significantly impact the cloud's microphysical composition, such as the number, density, and size spectra of cloud droplets. Direct numerical simulation (DNS), a computationally expensive method, is the best way to investigate these processes. The relevance of DNS in studying droplet dynamics, aerosol activation, and turbulent characteristics will be discussed in this talk. It will also cover a discussion on a new technique called 'Scaled-up DNS' and the possibility of improving LES grids, as well as a few techniques for analyzing turbulent characteristics using DNS data.

Abstract:
Mangroves are vegetation that grows at the interface between land and sea, mainly in tropical latitudes. Nowadays, ' mangrove' is used broadly to describe the highly adapted intertidal tropical forest communities or the ecosystem itself. Among the Indian mangroves, the Sundarban mangrove on the east coast is the largest forest and only mangrove Tigerland in the world. In Sundarban, approximately 60% of the mangrove forests fall in Bangladesh and 40% in India. The region consists of numerous islands and islets with an extensive network of estuaries, rivers, cross channels and creeks. Due to the availability of nutrients, solar radiation, rainfall & geographic position, the discovered biodiversity status of Sundarban is globally highest. The mangrove vegetation has particular adaptations. As the habitat is unique and full of environmental stresses, this ecosystem's living components are unique in their morphological, anatomical, physiological and behavioural patterns. Over the past three decades, Sundarban received several status nationally and internationally.

The Millennium Ecosystem Assessment (MA), an initiative of UN, has identified four major categories of ecosystem services. Sundarban mangroves provide all these four types of services through the following components- a. Provisioning Services (mangroves as food, timber, wood fuel, medicinal uses etc); b. Regulating Services (mangroves have capacity to reduce pollution, bees pollinate flowers, and tree roots hold soil in place to prevent erosion, carbon storage and climate regulations); c. Cultural Services (Mangroves play an essential role in the cultural, recreational, intellectual, and social development along with non-material benefit that contributes to the development and cultural advancement of local people); d. Supporting Services (Mangroves provide other services like photosynthesis, nutrient cycling, the creation of soils, and the water cycle).

There is a good relationship between salinity levels and vegetation community composition, but with time, this mangrove is going to be deteriorated due to anthropogenic exploitation of resources. It is very much necessary for wise and sustainable use of these forest resources and consequently to protect and conserve the biodiversity by taking appropriate management strategy. As a living component, mangroves are self-maintaining and renewable. As a coastal protection barrier, mangroves maintain themselves at no cost. In the event of a severe tropical storm, the damage they sustain will be self-repaired without any cost. Similarly, both the direct and indirect harvests of products from mangroves are renewable. However, the mangrove resource is renewable only if the ecological processes governing the system are maintained.

The internal ecological processes responsible for maintaining and renewing the mangrove ecosystem are primarily regulated by external processes that rely on i) an adequate amount and balance between fresh and salt water, ii) an adequate supply of nutrients and iii) a stable substrate. Modification of one or more of these critical factors will severely impair or eliminate the renewability of the mangroves. The continued conservation practices and appropriate management of the Sundarban, the largest tract of mangrove in India, therefore would play a significant role in the state of mangrove in the country, and is vital to the economic and social well-being of communities who depend directly or indirectly on the products of the mangrove ecosystem of Sundarban.

Abstract:
The evaporative sources and their variability responsible for the South Asian summer monsoon precipitation were investigated using Lagrangian atmospheric water-mass trajectories. The results indicated that evaporated waters from the Central and South Indian Ocean are the dominant contributors to the total South Asian summer monsoon rainfall, followed by the contribution from the local recycling, the Arabian Sea, remote sources and the Bay of Bengal.It was also found that although the direct contribution originating from the Bay of Bengal is small, it still provides a route for the masses of water that come from other regions. The outcomes further revealed that the atmosphericwaters originating from the Central and South Indian Ocean are responsible for the net precipitation over the coastal regions of the Ganges-Brahmaputra-Meghna Delta, Northeast India, Myanmar, the foothills of the Himalayas and Central-East India. Evaporated waters from the Arabian sea are mainly contributing to the rainfall over the Western coast and West-Central India. Summer monsoon precipitation due to the local recycling is primarily restricted to the Indo-Gangetic plain. No recycled precipitation was observed over the mountain chain along the West coast of India (Western Ghats). The inter-annual variability of the South Asian summer monsoon precipitation was found to be mainly controlled by the water-masses from the Central and South Indian Ocean.

Abstract
The quantum theory of nature, formalized in the first few decades of the 20th century, contains elements that are fundamentally different from those required in the classical description of nature. Based on the laws of quantum mechanics, in recent years, several discoveries have been reported which can revolutionize the way we think about modern technologies. I will talk about such inventions in the field of communication and some of our recent results towards building communication network.

Abstract
The quantum theory of nature, formalized in the first few decades of the 20th century, contains elements that are fundamentally different from those required in the classical description of nature. Based on the laws of quantum mechanics, in recent years, several discoveries have been reported which can revolutionize the way we think about modern technologies. I will talk about such inventions in the field of communication and some of our recent results towards building communication network.

Abstract
Brief Introduction: Dr Nils P. Wedi joined European Centre for Medium Range Weather Forecast (ECMWF) in 1995. He received his PhD degree from the Ludwig-Maximilians-Universität München. His career at ECMWF encapsulates a diverse range of work both technical and scientific. He has been a Principal Scientist since 2010 and is the Head of Earth System Modelling at ECMWF that addresses all aspects of scientific and computational performance relating to ECMWF's forecast model and the ensemble forecasting system. He develops strategies to secure the scalability of the model on future high-performance computing systems. He is the scientific coordinator of the European H2020 project ESCAPE to address the challenges of rising energy cost for computing towards affordable, exascale high performance simulations of weather and climate, and he is a member of the WMO working group on numerical experimentation (WGNE)

Abstract
The study examines the impacts of Indian Ocean Dipole Mode (IOD) on the upper ocean carbon cycle and its variability in the Indian Ocean with available biogeochemical observations and 60 years (1960-2019) of model outputs from a global ocean biogeochemical general circulation model. The upper ocean carbon cycle variability of the Indian Ocean is faithfully reproduced by the model when compared with available observations. The IOD leads to a substantial sea-to-air CO2 flux variability in the southeastern tropical Indian Ocean over a broad region (70o E-105o E, 0-20o S), with more focus near the coast of Java-Sumatra due to the prevailing upwelling dynamics and associated westward propagating anomalies. The sea-to-air CO2 fluxes, surface ocean partial pressure of CO2 (pCO2), the concentration of dissolved inorganic carbon (DIC), and ocean alkalinity (ALK) range as much as ±1.0 mole m-2 yr-1, ±20 μatm, ± 35 μmole kg-1, and ± 22 μmole kg-1 within 80o E-105o E, 0-10o S due to IOD. The DIC and ALK are significant drivers of pCO2 variability associated with IOD. The roles of temperature (T) and biology are found negligible. A relatively warm T and extremely high freshwater forcing make the southeastern tropical Indian Ocean carbon cycle variability submissive to DIC and ALK evolutions in contrast to the tropical eastern Pacific where changes in DIC and T dominate the pCO2 interannual variability. For the first time, this study provides a most comprehensive and extended analysis for the region while highlighting significant differences in carbon cycle variability of the eastern tropical Indian Ocean compared to that of the other parts of the global oceans.

Abstract
All are welcome to attend the webinar. The coupling of the El Niño–Southern Oscillation (ENSO) and Indian monsoon (IM) is central to seasonal summer monsoon rainfall predictions over the Indian subcontinent, although a nonstationary relationship between the two nonlinear phenomena can limit seasonal predictability. Radiative effects of volcanic aerosols injected into the stratosphere during large volcanic eruptions (LVEs) tend to alter ENSO evolution; however, their impact on ENSO-IM coupling remains unclear. Here, we investigate how LVEs influence the nonlinear behavior of the ENSO and IM dynamical systems using historical data, 25 paleoclimate reconstructions, last-millennium climate simulations, large-ensemble targeted climate sensitivity experiments, and advanced analysis techniques. Our findings show that LVEs promote a significantly enhanced phase-synchronization of the ENSO and IM oscillations, due to an increase in the angular frequency of ENSO. The results also shed innovative insights into the physical mechanism underlying the LVE-induced enhancement of ENSO-IM coupling and strengthen the prospects for improved seasonal monsoon predictions. In this ongoing PhD work, the role of volcanic and anthropogenic aerosols on the tropical ocean-atmosphere-land coupled system and Monsoon is proposed to be investigated.

Abstract
Reactive trace gases such as halogens compounds and dimethyl sulphide (DMS) play an important role in regulating the Earth's atmosphere through effects on the oxidising capacity and affecting the radiation budget. Over the last few years, new work has been carried out in the Indian Ocean, Indian sector of the Southern Ocean and in Antarctica, which is questioning our current understanding of this chemistry. This talk will focus on the emission of halogens, emissions of DMS and their implications on climate. It will also briefly discuss ozone in the stratosphere over Antarctica, showing the need for continued ground-based observations.

The summer monsoon circulation plays a vital role in the long-range transport of chemicals (gases and aerosol particles) to the upper troposphere and lower stratosphere (UTLS). The satellite observations and our chemistry-climate model (ECHAM6-HAMMOZ) simulations show their confinement within the monsoon anticyclone from June to September. The model simulations reveal that chemical species (aerosols, NOX, ozone, water vapour, HCN, PeroxyAcetyl Nitrate (PAN), HNO3, methane, CFCs, etc.) are further transported above the tropopause into the lower stratosphere which alters the chemical composition and thermal structure of the stratosphere.
Numbers of simulations performed for various realistic emission scenarios over Asia show that confined gases and aerosols in the UTLS produce a significant impact on monsoon dynamics by altering the heating rates and radiative forcing. The chemical heating/cooling of the anticyclone intensifies/abates event of Rossby wave breaking and tropopause folding over the Tibetan Plateau region. Our studies show that Rossby wave breaking influences the transport between troposphere-stratosphere and tropics-extratropics, impacting the Indian monsoon circulation.