About this Research Topic
In the last several decades, isotopic analysis of the water cycle involving rain, snow, surface water, and groundwater, provided useful information on various aspects of atmospheric and surface hydrological processes that have greatly enriched our understanding of the overall portioning of the Earth's water cycle. Water stable isotopes have diverse applications in hydrological studies, starting from the weather scale to long-term climate change processes. For example, this technique is widely used in the study of synoptic-scale atmospheric phenomena, convective systems, cyclonic events, and the role of stratiform versus convective processes in tropical rainfall. On the other hand, water isotopes compositions also provided long-term climate change information. For instance, the isotopic analysis of ice cores delivered information on temperature, moisture sources, sea ice conditions from interannual to millennial timescales.
Stable isotope hydrology has made substantial progress in the last decade. The GNIP (Global Network of Isotopes in Precipitation) initiative produces isotopic data of precipitation and other associated parameters, mostly on a monthly scale. The monthly composited samples, however, are not suitable to study the processes which operate on short temporal scales. Atmospheric processes, such as cloud microphysics, moisture transport, low-pressure systems, and moisture residence time take place on sub-diurnal to weekly timescale. Similarly, ground-water dynamics, such as percolation of water through the bedrock and subsequent formation of speleothems may take place from few years to millennia. The study of the modern processes and the process of decoding the isotopic signature in climate archives both require high-resolution sampling.
Due to sustained rise in surface temperature, the water cycle is undergoing a significant change. While atmospheric water vapor increases at a rate of 7%, the global precipitation is estimated to increase about 3% for each degree Celsius of warming. Though our understanding of the evaporation process is quite robust, precipitation mechanisms are still understudied. Hence a better understanding of the thermodynamic behaviour of the precipitation and vapor isotopes in respect of the changing hydrological cycle may provide better insight into the hydrological processes.
Therefore, the primary objective of this Research Topic is to (a) understand the hydrological processes on multiple temporal and spatial scales and (b) address various issues related to the hydrological cycle and their application in long-term climate reconstruction. The following broad topics are envisaged for the Research Topic:
• To improve the water balance models on a regional scale by using precipitation and vapor isotope data.
• To investigate precipitation isotopic responses to large scale atmospheric circulations such as Walker and Hadley cells, among other extreme events such as tropical cyclones.
• To underpin groundwater dynamics and rainwater-groundwater interactions on regional scales using stable water isotopes.
• To study interannual to centennial-scale climate variability using stable isotopes from high-resolution climate archives.
• To characterize the monsoon/ENSO variability using the present-day precipitation isotope data and to improve the paleo reconstruction.
• To examine paleo-temperature and paleo-precipitation variation using carbonate clumped isotope thermometry along with conventional stable isotopes from natural archives.
• Investigation of precipitation isotope-climate linkages using isotope-enabled general circulation models.
• To elucidate the extent to which regional or local processes control the spatial and temporal isotopic variability in precipitation.
• To promote triple oxygen isotopes applications to better understand the water cycle and reconstruction of past climate.
Keywords: precipitation, water isotopes, water cycle, climate variability, monsoons
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