Thejna Tharammal

Indian Institute of Science | IISC · Centre for Atmospheric and Oceanic Sciences (CAOS)

To understand the validity of δ18O proxy records as indicators of past temperature change, a series of experiments was conducted using an atmospheric general circulation model fitted with water isotope tracers (Community Atmosphere Model version 3.0, IsoCAM). A pre-industrial simulation was performed as the control experiment, as well as a simulati...

The empirical "amount effect" observed in the distribution of stable water isotope ratios in tropical precipitation is used in several studies to reconstruct past precipitation. Recent observations suggest the importance of large-scale organized convection systems on amount effect. With a series of experiments with Community Atmospheric Model versi...

Terrestrial and oceanic carbon sinks together sequester >50% of the anthropogenic emissions, and the major uncertainty in the global carbon budget is related to the terrestrial carbon cycle. Hence, it is important to understand the major drivers of the land carbon uptake to make informed decisions on climate change mitigation policies. In this pape...

The variation of stable water isotopes (δ18O, δD) in climate archives is an important proxy to understand the evolution of South Asian monsoon (SA) precipitation over the Holocene. In this study, using an isotope-enabled climate-model, we examine the responses of water isotopes in precipitation over the SA region to orbital changes in the early to...

Anthropogenic influences and global climate change are expected to alter the land carbon stocks in the future. In this modeling study, using the NCAR Community Earth System Model (CESM), we assess the relative importance of CO2 fertilization, nitrogen deposition, climate change, and land use and land cover changes (LULCC) on the land carbon uptake...

The Indian Summer Monsoon (ISM) is a major global climatic phenomenon. Long-term precipitation proxy records of the ISM, however, are often fragmented and discontinuous, impeding an estimation of the magnitude of precipitation variability from the Last Glacial to the present. To improve our understanding of past ISM variability, we provide a contin...

Carbon and water isotopes are included as passive tracers in the MIT general circulation model (MITgcm). The implementation of the carbon isotopes is based on the existing MITgcm carbon cycle component and involves the fractionation processes during photosynthesis and air-sea gas exchange. Special care is given to the use of a real freshwater flux...

Stable isotopes of water recorded in polar ice cores are used to reconstruct past temperatures and the fractionation during phase changes make them a useful tracer of the hydrological cycle. This study focuses on the global and regional variations in the distribution of water isotopes with changes in the climate. Sensitivity experiments and time-sl...

To understand the validity of d18O proxy records as indicators of past temperature change, a series of experiments was conducted using an atmospheric general circulation model fitted with water isotope tracers (Community Atmosphere Model version 3.0, IsoCAM). A pre-industrial simulation was performed as the control experiment, as well as a simulati...

The hydrogen isotopic composition of plant leaf-wax n-alkanes (dDwax) is a novel proxy for estimating dD of past precipitation (dDp). However, vegetation life-form and relative humidity exert secondary effects on dDwax, preventing quantitative estimates of past dDp. Here, we present an approach for removing the effect of vegetation-type and relativ...

A series of experiments was conducted using a water isotope tracers-enabled atmospheric general circulation model (Community Atmosphere Model version 3.0, CAM3.0-Iso), by changing the individual boundary conditions (greenhouse gases, ice sheet albedo and topography, sea-surface temperature) each at a time to Last Glacial Maximum (LGM) values. In ad...

Arabian sea is one of the highly productive seas in the Indian ocean region due to its long boundaries and the open ocean processes which manifest as upwelling during summer monsoon (June-September) and cooling during winter especially in the northern regions. The present study is aimed at applying ocean color satellite imagery to understand the se...