Spatio-temporal evaluation of event detection and measurement coherence among satellite rainfall products for ensembled dataset generation

Theoretical and Applied Climatology - Selection of a best suited satellite-based gridded rainfall product (SGRP) is challenging due to their significant variations at spatial and temporal scale....     

Perception and knowledge about climate change and health problems: a study in Kolkata Metropolitan Region

In the twenty-first century, land use changes, massive expansion of urbanization, population growth, economic crisis, environmental issues are the main challenges of developing countries. Climate change and its effects on human health are the major concerns for the different age groups of the population. The study delved into the causes associated with climate change and climate change-related myriad health impacts on the study population. This study has used a concurrent mixed-method research design. The quantitative and qualitative data were collected from the study area. Perception and knowledge about climate change and its consequences on health was based on a quantitative approach of Bi-variate analysis and Chi-Square test and Fisher’s exact test; this study also used qualitative data analysis. Study results show that most respondents pointed out that temperature increases throughout the year and 90% of the respondents reported that rainfall pattern has also changed. Similarly, 65% of respondents agreed in their statements in favour of increased natural calamities in this region. The study findings show that more than 40% of population faces dengue fever and 10% of people also suffer from malaria. More than 60% of the urban population suffered from asthma. Similarly, more than 70% of the population also got affected by cold and cough due to weather variability. Focus Group Discussion (FGD) and In-depth interviews of the participants also affirmed the fact that climate variability induced diseases and health problems in Kolkata Metropolitan areas. Urban residents perceived that excessive urbanization contributes to the changes in regional climate and human health. The study will encourage the policy-makers and local government to mitigate adverse health effects driven by climate change in the Kolkata Metropolitan Region.

     

Identification of cross-valley faults in the Maynardville Limestone,Oak Ridge Reservation,Tennessee, using seismic refraction tomography

First arrival times from P-wave refraction and reflection seismic surveys along Bear Creek Valley on the Oak Ridge Reservation, Tennessee, were inverted to produce refraction tomographic velocity images showing seismic velocity variations within thinly mantled karstic bedrock to a depth of approximately 20 m. Inverted velocities are consistent with two distinct bedrock groups: the Nolichucky Shale (2,730–5,150 m/s) and Maynardville Limestone (3,940–7,575 m/s). Low-velocity zones (2,700–4,000 m/s) in the tomographic images correspond to previously inferred cross-valley strike-slip faults; in places, these faults create permeability barriers that offset or block groundwater flowing along Bear Creek Valley. These faults may also force groundwater contaminants, such as dense non-aqueous phase liquids, to migrate laterally or downward, spreading contamination throughout the groundwater system. Other, previously unmapped cross-valley faults may also be visible in the tomographic images. Borehole logs suggest the low-velocity values are caused by low rigidity fractured and vuggy rock, water zones, cavities and collapse features. Surface streams, including Bear Creek, tend to lie directly above these low-velocity zones, suggesting fault and fracture control of surface drainage, in addition to the subsurface flow system. In some cases, fault zones are also associated with bedrock depressions and thicker accumulations of unconsolidated sediment.     

A study on the number of snow days over Eurasia, Indian rainfall and seasonal circulations

Summary In this paper, the relationship between seasonal mean (June, July, August and September) monsoon circulation features and the midlatitude circulations in winter and spring seasons have been examined during contrasting years of more (less) number of snow days in winter/spring followed by deficient (excess) Indian Summer Monsoon Rainfall (ISMR) using NCEP/NCAR reanalyzed data for the period 1966–1994. The Historical Soviet Daily Snow Depth (HSDSD) version II data set has been used to calculate the number of days of snow over west and east Eurasia separately under three classes: class 1 for SD>5cm, class 2 for SD>10cm and class 3 for SD>50cm where SD stands for snow depth. Correlation coefficients are computed between the anomaly in the number of days of snow depth under the above three classes during winter/spring over west and east Eurasia and the subsequent ISMR. HSDSD data show that difference in the number of days of SD>10cm in two extreme years is most prominent in the west Eurasia in the months of January and April. Also the anomaly in the number of days of snow in January and April over west Eurasia has correlation coefficients of –0.69 and –0.56 with the following ISMR, respectively at 0.1% significance level when the SD is more than 10cm at all the stations. Results also show that low-level atmospheric temperature difference between two extreme years of snow days in winter is up to 10°C and the cooling persists up to spring season with a difference of 2°C. This cooling persistence may give rise to anomalous cyclonic circulations over the midlatitudes and tropics which may be responsible for weakening the monsoon circulation over India during the year of more snow days over west Eurasia.     

Glacier surface characteristics derivation and monitoring using Hyperspectral datasets: a case study of Gepang Gath glacier,Western Himalaya

Mountain Glaciers are natural resources of fresh water and these affect the stream flow of the rivers, regional climate and further global climate. Observed trends and projected future evolutions of climate and Cryospheric variables clearly suggest a need to monitor these changes. Accordingly, the article presents the glacier features mapping using Hyperspectral remote sensing imagery. A freely available Hyperion satellite imagery acquired over Gepang Gath glacier in Himachal Pradesh, India is used for the study. Each class is identified based on their surface characteristics of spectral reflectance properties. Identification is simplified by demarcating the study glacier into accumulation and ablation areas through snowline. Accumulation area is characterized with high reflectance clean snow/ice and reduced moderate reflectance Snow/firn. The identification of classes in Hyperion imagery is validated using the spectral library from USGS and ASTER, and field spectra obtained from literature.     

Hyper-spectral data based investigations for snow wetness mapping

Spatial information on snow wetness content (SWC) is important for hydrology, climatology applications. Limited work is available on estimation of SWC using optical sensors. In present work, spectral signature characteristics of snow (~145 samples) acquired in winters of three years, using field spectral-radiometer (350–2500 nm) were correlated with synchronized SWC measurements. Correlation is found stronger in Near-Infra-Red (NIR) and Short-Wave-Infrared (SWIR) regions than Visible (VIS). Spectral peak width at 905 and 1240 nm is found negatively correlated with SWC, while positively correlated at 1025 nm. Asymmetry tends towards right as SWC increases and has stable positive correlations as compared to other characteristics. Sensitivity of widely used snow-related indices to SWC is also analyzed. Based on analysis, new ratio method at selected wavelengths is proposed to discriminate dry and wet snow zones using air/ground borne sensors. Proposed methodology is evaluated on air-borne hyper-spectral (AVIRIS-NG) data and 88% overall accuracy with kappa coefficient 77.6 observed after validation with reference observations.     

GEOLOGICAL STUDIES OF METAMORPHIC ROCKS IN THE VICINITY OF M.C.T./LESSER HIMALAYAN SHEAR ZONE, PARTS OF SIKKIM HIMALAYAS

GEOLOGICAL STUDIES OF METAMORPHIC ROCKS IN THE VICINITY OF M.C.T./LESSER HIMALAYAN SHEAR ZONE, PARTS OF SIKKIM HIMALAYAS     

Numerical simulation of cloud burst event on August 05, 2010, over Leh using WRF mesoscale model

Localized deep cumulus convective clouds have a capability of giving enormous amount of rainfall over a limited horizontal area, within a short span of time. Such types of extreme rainfall events are most common over the high elevated areas of Northern India during the Southwest monsoon season which causes widespread damage to the property and lives. Therefore, it is necessary to predict such extreme events accurately to avoid damage associated with them. The numerical mesoscale model Weather Research and Forecasting has been used to simulate the cloud burst event of Leh on August 05, 2010, so as to capture the main characteristics of the various parameters associated with this localized mesoscale phenomenon. The model has been integrated with four nested domains keeping Leh and its adjoining area as center. Two cloud microphysics parameterization schemes namely WSM3 and WSM6 have been used for the sensitivity experiments and results have been analyzed to examine the performance of both the schemes in capturing such extreme localized heavy rainfall events. Results show that the WSM6 microphysics was able to simulate the precipitation near to the observation. WSM3 microphysics simulated the location of the circulation near to the observation. In addition, the results also show that the maximum magnitudes of meridional and vertical wind as simulated with WSM3 microphysics are 12 and 4 m/s, respectively.     

Investigations on Influence of Bio-Geo Interface on Suction Characteristics of Fine-Grained Soil

Dependence of soil suction on factors such as formation of the soil, its particle size, mineralogy, pore-size distribution characteristics, water content, fabric, stress history and presence of salts has been extensively investigated by researchers. However, the influence of the microbial presence and its activity on the soil suction has not yet received researchers’ attention. With this in view, a methodology that facilitates investigation regarding the presence of ‘soil-microbial interface’, which has been termed as ‘bio-geo interface’, has been proposed in this study. Furthermore, the influence of this ‘interface’ on suction characteristics of such soils has also been investigated and the utility of the proposed methodology in addressing such issues, successfully, has been demonstrated.