Modulation of ISOs by land-atmosphere feedback and contribution to the interannual variability of Indian summer monsoon

A mechanism of internal variability of Indian summer monsoon through the modulation of intraseasonal oscillation (ISO) by land-atmosphere feedback is proposed. Evidence of feedback between surface soil moisture and ISOs is seen in the soil moisture data from GSWP-2 and rainfall data from observations. Using two sets of internal simulation by a regional climate model (RCM), it is shown that internally generated anomalous soil moisture interacts with the following ISO and generates interannual variability. To gain further insight, 27 years of sensitivity experiment by prescribing wet (dry) soil moisture condition during break (active) period along with a control simulation are carried out. The sensitivity experiment reveals the large-scale nature of soil moisture and ISO feedback which takes place through the changes in atmospheric stability by altering lower-level atmospheric conditions. The feedback is inherent to the monsoon system and a part of it acts through the intraseasonal varying memory of soil moisture. The RCM used to test the hypothesis is constrained by one-way interactions at the lateral boundary. Experiments with a much larger domain upheld the findings and hence suggest the true nature of soil moisture and ISO feedback present in the monsoon system

Effect of feeding sugarcane press mud on carcass traits and meat quality characteristics of lambs

Aim: To explore the possibilities of feeding unconventional agro-industrial byproduct for livestock production. Sugarcane press-mud (SPM), is a byproduct derived from sugarcane industry, which is rich in protein as well as minerals. The effects of dietary inclusion of SPM at different levels on the carcass characteristics of lambs were evaluated. Materials and Methods: SPM was incorporated in concentrate mixture at different levels 0% (SP0 - concentrate mixture without SPM [Control diet]), 10% (SP10 - concentrate mixture containing 10% SPM) and 20% (SP20 - concentrate mixture containing 20% SPM). The concentrate mixtures were fed along with wheat straw for 180 days. At the end of the experimental period, six lambs per group were slaughtered to evaluate carcass and meat quality characteristics. Results: No significant difference was observed in dressing percentage on pre-slaughter weight or empty body weight basis of lambs fed different levels of SPM incorporated diets. Likewise carcass weight, carcass length, and wholesale cuts appeared to have similar values among groups. The yield of visceral organs, chemical composition, and sensory attributes were not statistically affected by inclusion of SPM in the diets except juiciness of control group meat was significantly (p<0.05) higher than treatment group (SP20). Conclusion: The SPM can be incorporated in the diet of lambs up to the level of 20% without affecting the carcass characteristics of lambs

Pre-onset land surface processes and 'internal' interannual variabilities of the Indian summer monsoon

It is proposed that, land-atmosphere interaction around the time of monsoon onset could modulate the first episode of climatological intraseasonal oscillation (CISO) and may generate significant 'internal' interannual variation in the Indian summer monsoon rainfall. The regional climate model RegCM3 is used over Indian monsoon domain for 27 years of control simulation. In order to prove the hypothesis, another two sets of experiment are performed using two different boundary conditions (El Nino year and non-ENSO year). In each of these experiments, a single year of boundary conditions are used repeatedly year after year to generate 'internal' interannual monsoon variability. Simulation of monsoon climate in the control model run is found to be in reasonably good agreement with observation. However, large rainfall bias is seen over Arabian Sea and Bay of Bengal. The interannual monsoon rainfall variability are of the same order in two experiments, which suggest that the external influences may not be important on the generation of 'internal' monsoon rainfall variability. It is shown that, a dry (wet) pre-onset land-surface condition increases (decreases) rainfall in June which in turn leads to an anomalous increase (decrease) in seasonal (JJAS) rainfall. The phase and amplitude of CISO are modulated during May-June and beyond that the modulation of CISO is quite negligible. Though the pre-onset rainfall is unpredictable, significant modulation of the post-onset monsoon rainfall by it can be exploited to improve predictive skill within the monsoon season

Effects of multilayer snow scheme on the simulation of snow: Offline Noah and coupled with NCEPCFSv2

Abstract The Noah version 2.7.1 is a moderately complex land surface model (LSM), with a single layer snowpack, combined with vegetation and underlying soil layer. Many previous studies have pointed out biases in the simulation of snow, which may hinder the skill of a forecasting system coupled with the Noah. In order to improve the simulation of snow by the Noah, a multilayer snow scheme (up to a maximum of six layers) is introduced. As Noah is the land surface component of the Climate Forecast System version 2 (CFSv2) of the National Centers for Environmental Prediction (NCEP), the modified Noah is also coupled with the CFSv2. The offline LSM shows large improvements in the simulation of snow depth, snow water equivalent (SWE), and snow cover area during snow season (October to June). CFSv2 with the modified Noah reveals a dramatic improvements in the simulation of snow depth and 2 m air temperature and moderate improvements in SWE. As suggested in the previous diagnostic and sensitivity study, improvements in the simulation of snow by CFSv2 have lead to the reduction in dry bias over the Indian subcontinent (by a maximum of 2 mm d−1). The multilayer snow scheme shows promising results in the simulation of snow as well as Indian summer monsoon rainfall and hence this development may be the part of the future version of the CFS

Source identification and potential health risks from elevated groundwater nitrate contamination in Sundarbans coastal aquifers, India

Abstract In recent years groundwater contamination through nitrate contamination has increased rapidly in the managementof water research. In our study, fourteen nitrate conditioning factors were used, and multi-collinearity analysis is done. Among all variables, pH is crucial and ranked one, with a value of 0.77, which controls the nitrate concentration in the coastal aquifer in South 24 Parganas. The second important factor is Cl−, the value of which is 0.71. Other factors like—As, F−, EC and Mg2+ ranked third, fourth and fifth position, and their value are 0.69, 0.69, 0.67 and 0.55, respectively. Due to contaminated water, people of this district are suffering from several diseases like kidney damage (around 60%), liver (about 40%), low pressure due to salinity, fever, and headache. The applied method is for other regions to determine the nitrate concentration predictions and for the justifiable alterationof some management strategies

Linkage between precipitation isotopes and biosphere-atmosphere interaction observed in northeast India

© 2022, The Author(s).The intra-seasonal variation in precipitation isotopes shows a characteristic declining trend over northeast India. As of now, no mechanism offers a consistent explanation of this trend. We have performed the isotopic analysis of precipitation (rain) and estimated net ecosystem exchange and latent heat fluxes using an eddy-covariance system in northeast India. Additionally, we have used a diagnostic model to determine the recycled rainfall in this region. We find a strong link between the enhanced ecosystem productivity and isotopic enrichment in rainwater during the premonsoon season. Subsequently, on the advent of monsoon, the Bay of Bengal generated moisture enters this region and depletes the isotopic values. Additionally, the regional-scale convective activities produce periodic lows in the precipitation isotopes. Contrary to the general understanding, our study shows that the internal factors, such as the local land-atmosphere interactions, rather than the external influences, play a significant role in governing the precipitation isotopes in northeast India.11Ysciescopu