Charu Singh

Evaluation of error in TRMM 3B42V7 precipitation estimates over the Himalayan region

Accurate precipitation measurement is crucial for weather forecasting and hydrological modeling. Tropical Rainfall Measuring Mission (TRMM) 3B42V7 satellite precipitation product offers an opportunity to monitor precipitation at high spatiotemporal resolution. However, it has several inherent errors related to observation, instrument, and rainfall retrieval algorithms. It is, therefore, essential to validate it with ground-based measurements. We divide the region into different elevation ranges and compare 3B42V7 with India Meteorological Department gauge-based measurements, so as to observe the behavior of satellite at different altitudes. This paper evaluates error characteristics of 3B42V7 using continuous and categorical validation schemes. The analysis reveals 3100 m altitude as the breakpoint for the satellite overestimating and underestimating rainfall amount for elevation ranges below and above it, respectively. It gives a poor positive correlation of ~0.23 between individual rainfall events, though the correlation improves (~0.67) for areal-averaged precipitation values. 3B42V7 also underestimates the frequency of actual rainfall events and is not very good at identifying correct rain and no-rain events with the overall accuracy of ~66%. Conclusively, the satellite exhibits comparatively better performance for 1000–2000 m elevations but exacerbates over higher-altitude regions. Further, we assess its capability for very heavy rainfall events using three percentile thresholds. The low-magnitude bias for 98th and 99th percentiles and high-magnitude bias for 99.99th percentile imply that 3B42V7 may not be suitable for the study of very heavy rainfall events. On the basis of these findings, it is recommended to improve satellite precipitation retrieval algorithms by incorporating topographical and local climatic factors into consideration.

On the dust load and rainfall relationship in South Asia: an analysis from CMIP5

This study is aimed at examining the consistency of the relationship between load of dust and rainfall simulated by different climate models and its implication for the Indian summer monsoon system. Monthly mean outputs of 12 climate models, obtained from the archive of the Coupled Model Intercomparison Project phase 5 (CMIP5) for the period 1951–2004, are analyzed to investigate the relationship between dust and rainfall. Comparative analysis of the model simulated precipitation with the India Meteorological Department (IMD) gridded rainfall, CRU TS3.21 and GPCP version 2.2 data sets show significant differences between the spatial patterns of JJAS rainfall as well as annual cycle of rainfall simulated by various models and observations. Similarly, significant inter-model differences are also noted in the simulation of load of dust, nevertheless it is further noted that most of the CMIP5 models are able to capture the major dust sources across the study region. Although the scatter plot analysis and the lead–lag pattern correlation between the dust load and the rainfall show strong relationship between the dust load over distant sources and the rainfall in the South Asian region in individual models, the temporal scale of this association indicates large differences amongst the models. Our results caution that it would be pre-mature to draw any robust conclusions on the time scale of the relationship between dust and the rainfall in the South Asian region based on either CMIP5 results or limited number of previous studies. Hence, we would like to emphasize upon the fact that any conclusions drawn on the relationship between the dust load and the South Asian rainfall using model simulation is highly dependent on the degree of complexity incorporated in those models such as the representation of aerosol life cycle, their interaction with clouds, precipitation and other components of the climate system.

Land Surface Temperature from INSAT‐3D Imager Data: Retrieval and Assimilation in NWP Model

A new algorithm is developed for retrieving the land surface temperature (LST) from the imager radiance observations on board geostationary operational Indian National Satellite (INSAT-3D). The algorithm is developed using the two thermal infrared channels (TIR1 10.3–11.3 µm and TIR2 11.5–12.5 µm) via genetic algorithm (GA). The transfer function that relates LST and thermal radiances is developed using radiative transfer model simulated database. The developed algorithm has been applied on the INSAT-3D observed radiances, and LST retrieved from the developed algorithm has been validated with Moderate Resolution Imaging Spectroradiometer land surface temperature (LST) product. The developed algorithm demonstrates a good accuracy, without significant bias and standard deviations of 1.78 K and 1.41 K during daytime and nighttime, respectively. The newly proposed algorithm performs better than the operational algorithm used for LST retrieval from INSAT-3D satellite. Further, a set of data assimilation experiments is conducted with the Weather Research and Forecasting (WRF) model to assess the impact of INSAT-3D LST on model forecast skill over the Indian region. The assimilation experiments demonstrated a positive impact of the assimilated INSAT-3D LST, particularly on the lower tropospheric temperature and moisture forecasts. The temperature and moisture forecast errors are reduced (as large as 8–10%) with the assimilation of INSAT-3D LST, when compared to forecasts that were obtained without the assimilation of INSAT-3D LST. Results of the additional experiments of comparative performance of two LST products, retrieved from operational and newly proposed algorithms, indicate that the impact of INSAT-3D LST retrieved using newly proposed algorithm is significantly larger compared to the impact of INSAT-3D LST retrieved using operational algorithm.

Biodegradation of Feather by Microsporum fulvum Singly or in Combination with Other Fungi

The course of feather degradation by Microsporum fulvum singly and in combination with Chrysosporium tropicum, C. vallenarense, C. quenslandicum and Microsporum boullardii was studied by measuring protein, amino acids, keratinase enzyme released in the culture medium and weight loss of feather by M. fulvum and the effect of addition of M. fulvum on continued degradation of feather by C. tropicum, C. vallenarense, C. quenslandicum and M. boullardii were also studied. The synergistic action of M. fulvum and C. tropicum on feather degradation was found to be more effective. The biodegradation ability of M. fulvum can be effective by C. tropicum and C. vallenarense if the latter fungi join midway of keratinolysis. M. fulvum was also effective on the biodegradation ability of C. tropicum. M. fulvum did not act as follower fungus in wool degradation.

Rainfall Characteristics over the Northwest Himalayan Region

The Northwest Himalayan (NWH) region constitutes a unique geographical setting with a complex interaction between atmosphere and topography. The region is also the birthplace of many perennial rivers like the Ganges, Yamuna, Indus, Chenab, etc. and their various tributaries. The precipitation processes in the region dominate not only the geomorphological processes and terrestrial hydrological cycle but are also highly relied upon for food and water availability, thus, playing a decisive role in the socio-economic survival of millions of people inhabiting the basins of these rivers. The precipitation pattern in this region is mainly controlled by two major atmospheric circulations: Indian summer monsoon (ISM) lasting from June to September and Western disturbances during the winter season from December to March. While the Eastern Himalayan ranges receive precipitation mainly through monsoon rains, the NWH receives both rainfall (liquid) and snow (solid) in summer and winter season, respectively. The monsoon rains contribute roughly 75–80% to the annual precipitation of the NWH and closely control the river discharge in the basins.

Investigation of the Relationship Between Natural Aerosols and Indian Summer Monsoon Rainfall Using a Climate Model

Using all forcing simulations of fully coupled climate model GFDL-CM3, an attempt has been made to represent the role of natural aerosols (such as dust) in modulating the summer monsoon rainfall over the Central Indian region. For this purpose, long-term data set of dust, winds and rainfall have been obtained from CMIP5 data portal for the past 54 years of time period. The spatial pattern of dust load from GFDL-CM3 is able to capture the potential dust sources such as Sahara Desert, Arabian Peninsula region. Further to this, it has been observed that the load of dust over the Arabian Sea and Arabian Peninsula is significantly correlated (significant at 1% significance level) with the rainfall over the central Indian region, suggesting an in-phase relationship between the two parameters.

Prevalence and Knowledge of Needle Stick Injury among the Health Care Workers in a Tertiary Care Hospital Solan H.P.

NSI is a major occupational health and safety issue faced by health-care professionals globally. National instate for occupational safety and health define NSIs as “injuries caused by needles such as hypodermic blood collection needles, IV styles and needles used to connect part of IV delivery system” (4).HCW are exposed to NSI from unsafe practices such as recapping of needles, manipulating used needles, such as bending, breaking or cutting hypodermic needles or passing of needles from one workers to another. It is revealed that the most common clinical activity to cause NSI was blood withdrawal, followed by suturing and vaccinations (5) Health care professionals are most negligent as far as their own health is concerned. Health care workers incur 2 million needle stick injuries (NSIs) per year as Needle stick injuries present the single greatest occupational hazard to medical personnel.(6) While as many as twenty blood borne pathogens can be transmitted through accidental needle sticks, the potentially life threatening are Human Immunodeficiency Virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV).(7) The World Health Organization estimates the global burden of International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 8 (2017) pp. 2486-2492 Journal homepage: http://www.ijcmas.com

Estimation of rain attenuation losses in signal link for microwave frequencies using ITU-R model

Estimation of rain attenuation is an important parameter for the designing of both satellite and terrestrial communications links operating in a tropical country like India especially for microwave frequencies above 10 GHz. The present study uses the ITU-R P618-8 rain attenuation model to determine the signal loss in the transmission link for microwave frequencies of 20.2 and 30.5 GHz at New Delhi. For this purpose, 1-hourly Automatic Weather Station (AWS) rain rate has been converted to 1-minute integration time using ITU-R P837-6, before being used in the attenuation model. Analysis suggests that the rain attenuation is directly proportional to the rain rate and microwave frequencies. Moreover, it has also been observed that if frequency increases by approximately 10 GHz, the percentage increase in the attenuation at New Delhi would be approximately 38% respectively. The preliminary results are encouraging and may be utilized to conduct the attenuation studies for forthcoming microwave frequency links in tropical regions in detailed manner for other spatial locations as well.

Aerosols and contrasting monsoon conditions over the Himalayan region

Impact of aerosols on the Indian summer monsoon (ISM) variability is well documented; however there are limited studies which have quantified the role of aerosols in modifying the amount of rainfall. To address this research problem, we make use of the remotely sensed data set of precipitation and aerosols from different observations. In the present study remotely sensed precipitation data set has been utilised to define contrasting monsoon conditions over the Himalayan region. As per the classical definition, active and break spells are defined over the central part of the Indian land region, and during the break spells over the central Indian region, the Himalayan region receives substantial amount of rainfall. It is found that accumulation of more dust over the Uttarakhand region significantly (negative correlation with rainfall; significant at 5% significance level) suppresses the rainfall during break spells. We propose that the substantial aerosol loading and its associated dynamical feedback over the Himalayan foothills may have considerable impact on the amount of rainfall over the mountainous regions of the Indian subcontinent. Results presented in this paper are supported by the statistically robust significance test and would be useful to develop the understanding of the role of aerosols in modulating the rainfall intensity during the summer monsoon season.