Variations in aerosol optical and microphysical properties during an Indian festival observed with space-borne and ground-based observations

This study analyzes changes in the response of meteorological parameters, aerosol, ozone, and water vapor properties over a tropical urban station in Pune, India, using ground-based and satellite data sets from February 23 to March 4, 2010 covering the Holi festival period. Continuous ground-based measurements of Microprocessor-based Total Ozone Portable Spectrometer (Microtops II) were made. The variations in aerosol optical depth (AOD) showed higher values on March 1, 2010 which coincide with the peak festival time. Using the least squares method, A °ngström exponent (α) is calculated in the spectral interval of 340-1020 nm, along with the coefficient a2 of the second-order polynomial fit to the plot of log AOD versus the log wavelength. The correlation between the coefficient a2 vs. AOD 500 nm is discussed. Results from ground-based Microtops and CIMEL sun-sky radiometer observations are also found to match well with satellite retrievals. The aerosol index (AI) derived from the Ozone Monitoring Instrument (OMI) along with AOD derived from the Moderate-Resolution Imaging Spectrometer (MODIS) indicate positive correlation. This suggests that satellite observations over the region confirm the presence of absorbing aerosols mainly due to bio-mass burning and colored powder spray activities during the festival

Study of successive contrasting monsoons (2001-2002) in terms of aerosol variability over a tropical statio Pune, India

The present study suggests that aerosols play a major role in cloud formation and affect significantly the precipitation over a regional scale. The study reveals that there is a high variability of aerosol index during a bad monsoon year 2002, indicating an extension of cycle to more than 100 days from a normal 50 day cycle of absorbing and non-absorbing aerosols over a tropical urban station Pune. Pre-monsoon of 2002 shows a high loading of coarse-mode aerosols (absorbing dust aerosols) which indicate vertical and horizontal temperature variations in turn affecting the seasonal rainfall at a regional scale. Cloud formation highly depends on aerosol concentration, but the activation process is not monotonic. The surface meteorological features help to initiate the cloud process. The surface temperatures were high during the pre-monsoon of 2002 leading to increase of aerosol optical depth as compared to 2001. The effect of surface wind speed, though, complicated to understand, results in low values in 2002 with high aerosol optical depth and vice-versa in 2001

Staphylococci may indeed cause acute dental infections [7]

published_or_final_versio

Salivary flow rate, pH and lysozyme levels in HIV-infected individuals in Hong Kong

published_or_final_versio

Predominant cultivable subgingival microbiota of HIV-infected ethnic Chinese

published_or_final_versio

A study of lightning activity over land and oceanic regions of India

Monthly variations of lightning activity over typical land and oceanic regions of India were examined using satellite data (OTD) for a 5-year period (1995-1999). It is noted that the nature of variation between surface air maximum temperature (Tmax), thunderstorm days (Thn), and lightning flash count over ER and WR showed remarkable correspondence and sensitivity with each other on monthly time scale. As we move out of winter season and enter the monsoon season, via pre-monsoon season, the WR undergoes cooling relative to the ER in the range 0.1-1.2°C. As a result, WR experiences reduction of thunder days and lowering in flash count. This decrease in Tmax, Thn, and flash count over WR may also be associated with relatively small values of Tθw and CAPE in comparison with similar values over ER during the monsoon season. Our observation of associated reduction in Thn and lightning count per 1°C cooling in surface air maximum temperature suggests reduction of ~3.5 thunderstorms per station and 73 flashes. Comparison of lightning flashes between pairs of coastal, oceanic, arid-zone, hilly, and island stations reveals distinct relationship between climate regime and intensity of lightning activity. We may conclude the results of this study by saying that the overhead lightning activity is a clear reflection of the status of the underlying ground-earth properties. A close and continuous monitoring of lightning activity may be considered as a need of present day scientific studies

Atmospheric stability effects on aerosol structure and stratification

This paper essentially addresses the structure and stratification of the nocturnal boundary layer (NBL) derived from the vertical profile measurements of aerosol concentration made with a computer-controlled Argon ion lidar system at the Indian Institue of Tropical Meteorology (IITM), Pune, India. Companions are made between the lidar observations during clear night-sky conditions and concurrent aerometric observations carried out on some selected experimental days. The results show multiple stratified aerosol layer structures in the nocturnal lower atmosphere, which drift either upward or downward depending on atmospheric stability conditions prevailing at different altitudes. The normalized aerosol concentration gradient (NCG) profiles indicate the variations in the nocturnal mixing depth from 200 to 426 m and that in the stable layer height from 325 to 725 m during the period of observations. The importance of such observations in the context of monitoring and/or assesment of airborne particulate pollutants over the urban environments associated with non-uniform terrain is discussed

Aerosol radiative forcing over a tropical urban site in India

Using collocated measurements of aerosol radiative properties and radiative fluxes, aerosol radiative forcing is estimated at a tropical urban site in India, located between the sub-continent and the Indian Ocean Experiment [INDOEX] sites. Observed sun/sky radiance data are used to derive aerosol spectral optical depth, single scattering albedo [SSA], asymmetry parameter, precipitable water and total column ozone. These serve as inputs to a radiative transfer model, to estimate aerosol forcing at the surface, the top-of-the atmosphere [TOA] and the atmosphere. During the dry season of 2001 and 2002 [November–April], these were found to be −33, 0 and 33 Wm−2, respectively. Using measured radiative fluxes during different aerosol loading conditions yield a surface forcing of −31 Wm−2. The surface forcing efficiency as computed from the two independent methods is found to be −88 and −84 Wm−2, respectively, while mean SSA at 500 nm is found to be 0.8

Winter aerosol and trace gas characteristics over a high-altitude station in the Western Ghats, India

This paper presents spectral distribution of aerosol optical depth (and derived size distribution), water vapor and ozone in total atmospheric column; in conjunction with particulate mass concentration in the size range from 0.3 to 20 μm and black carbon mass concentration at the surface-level during four different campaigns, conducted in months of December-January-2006-2007 (Campaign I), February-2007 (Campaign II), January-2008 (Campaign III) and November-2008 (Campaign IV) at a high-altitude station, Sinhgad (18°22'N, 73°45'E, 1450 m AMSL) in the Western Ghats of Indian Peninsula. Aerosol optical depth (AOD) measured within the spectral range 440-1020 nm is found lower as compared to that measured over a nearby urban station, Pune; but relatively higher than that over other remote high-altitude stations in India. The columnar Angstrom exponent derived within the 440-870 nm spectral range showed maximum values close to 1 indicating relatively higher contribution from fine-mode particles to aerosol size spectrum. Interestingly, this parameter shows lower values when the total aerosol mass concentration exhibits higher values during afternoon hours. Both columnar water vapor (CWV) and ozone (TCO) exhibit lower values in the morning hours and higher in the afternoon hours. The mass concentration of black carbon shows an association with AOD during the study period over the station. The measured surface aerosol particle number concentrations are used to reconstruct AOD spectra using the Optical Properties of Aerosols and Clouds (OPAC) software package and compared with simultaneously available columnar AOD spectra

Relationship between plasma sialic acid and fibinogen concentration and incident micro-and macrovascular complications in type 1 diabetes

AIMS/HYPOTHESIS: Type 1 diabetes is associated with an increased risk of vascular complications. This increased risk could be explained by sialic acid and/or fibrinogen. It is also not clear what explains the abolition of sex-related differences affecting risk of CHD in the presence of type 1 diabetes. Therefore, we examined whether fibrinogen and sialic acid are related to incident micro- and macrovascular complications in patients with type 1 diabetes. METHODS: A subset (n=2329) of the EURODIAB Prospective Complications Study was analysed. Sialic acid and fibrinogen concentrations were measured at baseline. The main outcomes after 7 years were development of albuminuria, retinopathy, neuropathy and CHD. RESULTS: Univariable and multivariable models using Cox proportional survival analyses showed that an SD unit increase in sialic acid and fibrinogen levels was significantly associated with CHD in men only. Adjusted standardised hazard ratios (sHRs) were 1.50 (95% CI 1.05-2.15) and 1.40 (95% CI 1.06-1.86) for sialic acid and fibrinogen, respectively. Initial associations between (1) sialic acid and incident retinopathy [standardised odds ratio (sOR) men 1.68, 95% CI 1.10-2.57], (2) fibrinogen and retinopathy (sOR women 1.37, 95% CI 1.06-1.78) and (3) sialic acid and neuropathy (sOR men 1.37, 95% CI 1.06-1.77) were shown, but became non-significant in multivariable models. CONCLUSIONS/INTERPRETATION: Sialic acid and fibrinogen are strong predictors of CHD in men with type 1 diabetes, beyond the effect of established risk factors. The associations found with microvascular complications were not independent of other risk factors