Satellite Remote Sensing of Snow/Ice Albedo over the Himalayas

The Himalayan glaciers and snowpacks play an important role in the hydrological cycle over Asia. The seasonal snow melt from the Himalayan glaciers and snowpacks is one of the key elements to the livelihood of the downstream densely populated regions of South Asia. During the pre-monsoon season (April-May-June), South Asia not only experiences the reversal of the regional meridional tropospheric temperature gradient (i.e., the onset of the summer monsoon), but also is being bombarded by dry westerly airmass that transports mineral dust from various Southwest Asian desert and arid regions into the Indo-Gangetic Plains in northern India. Mixed with heavy anthropogenic pollution, mineral dust constitutes the bulk of regional aerosol loading and forms an extensive and vertically extended brown haze lapping against the southern slopes of the Himalayas. Episodic dust plumes are advected over the Himalayas, and are discernible in satellite imagery, resulting in dust-capped snow surface. Motivated by the potential implications of accelerated snowmelt, we examine the changes in radiative energetics induced by aerosol transport over the Himalayan snow cover by utilizing space borne observations. Our objective lies in the investigation of potential impacts of aerosol solar absorption on the Top-of-Atmosphere (TOA) spectral reflectivity and the broadband albedo, and hence the accelerated snowmelt, particularly in the western Himalayas. Lambertian Equivalent Reflectivity (LER) in the visible and near-infrared wavelengths, derived from Moderate Resolution Imaging Spectroradiometer radiances, is used to generate statistics for determining perturbation caused due to dust layer over snow surface in over ten years of continuous observations. Case studies indicate significant reduction of LER ranging from 5 to 8% in the 412-860nm spectra. Broadband flux observations, from the Clouds and the Earth's Radiant Energy System, are also used to investigate changes in shortwave TOA flux over dust-laden and dust-free snow covered regions. Additionally, spatio-temporal and intra-seasonal variations of LER, along with snow cover information, are used to characterize the seasonal melt pattern and thus to distinguish the outstanding aerosol-induced snowmelt signal. Results from this observational work are expected to provide better understanding of the radiative impact of aerosols over snow surface, especially its role in the Himalayan hydro-glacialogical variability

DEVELOPMENT AND VALIDATION OF ULTRAVIOLET SPECTROPHOTOMETRIC METHOD FOR QUANTITATIVE ESTIMATION OF FAMOTIDINE IN BULK AND TABLET DOSAGE FORM

  Objectives: The purpose of the study is to develop a simple, precise, economical, accurate, reproducible, and sensitive method for the estimation of famotidine (FAM) in bulk and its pharmaceutical dosage forms by ultraviolet (UV) absorption spectrophotometry.Methods: The method uses 0.1 N HCl, pH 1.20 as a solvent for the quantitative estimation of FAM in bulk and its tablets dosage form by UV absorption spectrophotometry.Results: FAM exhibited absorbance maxima at 266 nm in 0.1 N HCl, pH 1.20 solvent. The developed method was validated as per the ICH analytical method validation guidelines. Beer's law was obeyed in range of 0-30 μg/ml with r2=0.9998. The limit of detection and limit of quantification values of FAM were found to be 0.152 and 0.461 μg/ml, respectively. The mean percentage recovery for developed method was found to be in the range of 99.35-99.48%, respectively, for the marketed dosage forms. The developed method was also found to be robust and ensures bench-top stability.Conclusion: The developed method was found to be suitable for the routine quantitative analysis of FAM in bulk and pharmaceutical dosage form. It was also concluded that developed UV spectrophotometry method was accurate, precise, linear, reproducible, robust, and sensitive

Influences of Winter Haze on Fog/Low Cloud Over the Indo-Gangetic Plains

The aerosol loading in south Asia has increased considerably because of the growing population, urbanization, and industrialization in recent years. To understand the effects of aerosols on cloud properties in this region, we have analyzed an extensive collection of aerosol and cloud properties, obtained from the Moderate resolution Imaging Spectroradiometer (MODIS) data, over the Indian subcontinent during winter 2000–2006. During these winter months, the Indo-Gangetic (IG) plains, in the northern part of India, are subjected to dense haze and fog on the basis of MODIS climatology of aerosol optical depth and cloud properties (cloud effective radius, cloud top pressure, and cloud fraction), respectively. We derive a fog/low-cloud detection scheme from MODIS level 2 data to generate distribution of fog/low cloud on a daily basis for December–January 2000–2006. Interactions between winter haze and fog/low cloud over the IG plains were analyzed by minimizing the effect of dynamical processes associated with fog formation. On the basis of the interannual variability of meteorological parameters, winter 2004–2005 was associated with favorable conditions for fog formation in terms of comparable values of relative humidity with respect to previous years. However, significantly lower fog occurrences were found in winter 2004–2005 over the IG plains from MODIS and ground observations, while higher aerosol loading was observed in 2004–2005 compared to previous years. Thus the role of higher aerosol loading in 2004–2005 was investigated, combined with the high concentration of black carbon (BC) aerosols over the IG plains, indicated by aerosol transport model, suggesting that the BC aerosols may have significant impact on the fog/low-cloud formation over the IG plains and hence less fog in winter 2004–2005

FORMULATION AND EVALUATION OF FAMOTIDINE MICRO BALLOONS WITH ENHANCED ANTI-ULCER ACTIVITY

Objective: The aim of the present study was to formulate and optimize famotidine loaded micro balloons for enhancing bioavailability, increasing gastric residence time of drug and to achieve sustained release in the stomach.Methods: Microballoons were prepared using emulsion solvent diffusion method using HPMC K4M as the polymer. All the formulated microspheres were subjected to various evaluation parameters such as % drug entrapment, micromeritics properties, % buoyancy and in vitro drug release studies. The formulation was optimized using 32 full factorial design. Optimized formulation was subjective to in vivo floating (X-ray) and in vivo antiulcer studies.Results: The microballoons were smooth and spherical in shape and were porous in nature due to hollow cavity. Sustained/controlled release of drug was observed for more than 12 h. based on the results of % drug entrapment, in vitro drug release and % buoyancy studies, formulation F6 was selected as optimized formulation. The release kinetics of optimized formulation followed Higuchi model and mechanism of release was non-Fickian diffusion. Examination of the X-ray radiographic images taken during the study indicated that the optimized formulation remained buoyant and uniformly distributed in the gastric contents for a long period. In ethanol-induced ulcer model, drug-loaded microballoons treated group showed significant ulcer protection index of 83.26% as compared to the marketed brand of famotidine 76. 09% and untreated control group.Conclusion: Famotidine-loaded floating micro balloons were successfully prepared and prove to be useful for the prolonged gastric residence of the drug, better bioavailability, patient compliance and anti-ulcer activity

Improving Aerosol Simulation over South Asia for Climate and Air Quality Studies

Atmospheric pollution over South Asia attracts special attention due to its effects on regional climate, the water cycle, and human health. These effects are potentially growing owing to rising trends of anthropogenic aerosol emissions found there. However, it has been proved quite challenging to adequately represent the aerosol spatial distribution and magnitude over this critical region in global models (Pan et al. 2014), with the surface concentrations, aerosol optical depth (AOD), and absorbing AOD (AAOD) significantly underestimated, especially in October-January when the agricultural waste burning and anthropogenic aerosol dominate over dust aerosol. In this study, we aim to investigate the causes for such discrepancy in winter by conducting sets of model experiments with NASA's GEOS-5 in terms of (1) spatial resolution, (2) emission amount, and (3) meteorological fields

DEVELOPMENT AND VALIDATION OF UV SPECTROPHOTOMETRIC METHOD FOR QUANTITATIVE ESTIMATION OF LAFUTIDINE IN BULK AND PHARMACEUTICAL DOSAGE FORM

Objective: The objectives of the present research was to develop a simple, precise, economical, accurate, reproducible and sensitive method for the quantitative estimation of lafutidine in bulk and its pharmaceutical dosage forms by Ultra Violet (UV) absorption spectrophotometry.Methods: The method uses 0.1 N HCl, pH 1.20 as a solvent of choice for the quantitative estimation of lafutidine in bulk and its tablets dosage form by UV absorption spectrophotometry at a wavelength of 290 nm. The method was validated for parameters like linearity, range, precision, Limit of Detection (LOD), Limit of Quantification (LOQ), accuracy, recovery and stability of the analyte.Results: Lafutidine exhibited absorbance maxima at 290 nm in 0.1 N HCl, pH 1.20 solvent. The developed method was validated as per the ICH validation guidelines. Beer's law was obeyed in range of 0-30 µg/ml with r2= 0.9997. The LOD and LOQ values of lafutidine were found to be 0.545 µg/ml and 1.654 µg/ml respectively. The mean % recovery for the developed method was found to be in the range of 99.25 to 99.45 % respectively for the marketed dosage forms. The developed method was also found to be robust.Conclusion: The developed method was found suitable for the routine quantitative analysis of lafutidinein bulk and pharmaceutical dosage form. It was also concluded that developed UV spectrophotometry method was accurate, precise, linear, reproducible, robust and sensitive

Two Contrasting Dust-Dominant Periods over India Observed from MODIS and CALIPSO Data

Each year, prior to the onset of the Indian Summer Monsoon, the Gangetic Plains (GP), bounded by the high-altitude Himalayan mountains, are strongly influenced by the transport of dust outbreaks originating in the northwestern desert in India (known as the Thar Desert). Dust particles constitute the bulk of the regional aerosol loading which peaks annually during the pre-monsoon season. This paper integrates observations from space-borne sensors, namely MODIS and CALIPSO, together with ground sunphotometer measurements, to infer dust loading in the pre-monsoon aerosol build-up over source and sink regions in northern India. Detailed aerosol characterization from the synergetic observational assessment suggests that the two pre-monsoon seasons of 2007 and 2008 were strikingly contrasting in terms of the dust loading over both the Thar Desert and the GP. Further analysis of aerosol loading and optical properties, from the entire record of MODIS and sunphotometer observations, reveals that the 2007 pre-monsoon season was an unusually weak dust-laden period. Our findings suggest the plausible role of the immediately preceding excess winter monsoon rainfall in the suppressed dust activity during the 2007 pre-monsoon season

Developing an Aircraft-Based Angular Distribution Model of Solar Reflection from Wildfire Smoke to Aid Satellite-Based Radiative Flux Estimation

This study examines the angular distribution of scattered solar radiation associated with wildfire smoke aerosols observed over boreal forests in Canada during the ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) campaign. First, it estimates smoke radiative parameters (550 nm optical depth of 3.9 and single scattering albedo of 0.90) using quasi-simultaneous multiangular and multispectral airborne measurements by the Cloud Absorption Radiometer (CAR). Next, the paper estimates the broadband top-of-atmosphere radiances that a satellite instrument such as the Clouds and the Earths Radiant Energy System (CERES) could have observed, given the narrowband CAR measurements made from an aircraft circling about a kilometer above the smoke layer. This estimation includes both an atmospheric correction that accounts for the atmosphere above the aircraft and a narrowband-to-broadband conversion. The angular distribution of estimated radiances is found to be substantially different than the angular model used in the operational data processing of CERES observations over the same area. This is because the CERES model is a monthly average model that was constructed using observations taken under smoke-free conditions. Finally, a sensitivity analysis shows that the estimated angular distribution remains accurate for a fairly wide range of smoke and underlying surface parameters. Overall, results from this work suggest that airborne CAR measurements can bring some substantial improvements in the accuracy of satellite-based radiative flux estimates

Validating and Improving Long-Term Aerosol Data Records from SeaWiFS

Natural and anthropogenic aerosols influence the radiative balance of the Earth through direct and indirect interactions with incoming solar radiation. However, the quantification of these interactions and their ultimate effect on the Earth's climate still have large uncertainties. This is partly due to the limitations of current satellite data records which include short satellite lifetimes, retrieval algorithm uncertainty, or insufficient calibration accuracy. We have taken the first steps in overcoming this hurdle with the production and public release of an aerosol data record using the radiances from the Sea-viewing Wide Field-of-View Sensor (Sea WiFS). Sea WiFS was launched in late 1997 and provided exceptionally well-calibrated top-of-atmosphere radiance data until December 2010, more than 13 years. We have partnered this data with an expanded Deep Blue aerosol retrieval algorithm. In accordance with Deep Blue's original focus, the latest algorithm retrieves aerosol properties not only over bright desert surfaces, but also over oceans and vegetated surfaces. With this combination of a long time series and global algorithm, we can finally identify the changing patterns of regional aerosol loading and provide insight into longterm variability and trends of aerosols on regional and global scales. In this work, we provide an introduction to Sea WiFS, the current algorithms, and our aerosol data records. We have validated the data over land and ocean with ground measurements from the Aerosol Robotic Network (AERONET) and compared them with other satellites such as MODIS and MISR. Looking ahead to the next data release, we will also provide details on the implemented and planned algorithm improvements, and subsequent validation results