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.