We have utilized the Gadanki MST Radar and Rayleigh LIDAR to understand the vertical coupling between the lower atmosphere and mesosphere through the short-period gravity waves (GWs). The ...short-period GWs (20 min–2 h) are noticed both in the troposphere and in the mesosphere during the deep convection. During the convection, the large vertical velocities (>5 m/s) and significant variations in the momentum flux (∼3 m2/s2) are noticed in the troposphere and higher fluxes (∼45 m2/s2) are evidenced in the mesosphere. The observations suggest the vertical coupling between the lower and middle atmosphere during convection.
•MST Radar and LIDAR are used to study the vertical coupling during convection.•Short-period gravity waves are observed from the troposphere to mesosphere.•The gravity waves source region are discussed during convection.•Variability of momentum flux observed both in the troposphere and mesosphere.
To assess the HIV risk behaviours of male migrant contracted and non-contracted labourers in India and to understand the role of contract labour systems for use in HIV prevention efforts.
...Cross-sectional surveys (N = 11 219) were conducted with male migrant workers, aged 18-49 years from 21 districts in four high HIV prevalence states of India. Analyses involved data from the subsample of contracted labour (n = 3880; 35% of total sample) to assess the prevalence of HIV risk behaviours and sexually transmitted infection (STI) symptoms and further comparisons with non-contracted labourers.
Contracted male labourers are largely young; 70% were between the ages of 18 and 29 years. Over half (55%) were married, and a third (34%) resided away from their wives because of migrant work. More than one in six contract labourers (17%) reported having sex with a sex worker, and two-fifths of these reported an inconsistent use of condoms. One in 10 reported sex with both sex workers and non-spousal unpaid female partners in the past year in the places they had migrated to, and 31% reported sex with either a sex worker or non-spousal unpaid female partner in their places of origin over the past 2 years. After adjustment for sociodemographic characteristics, the contracted labourers were significantly more likely to report alcohol use and HIV risk behaviours than non-contracted labourers.
The existence of a wide network of labour contractors and a structured infrastructure of the contract system provides opportunities for effective and sustained worksite HIV prevention programmes among contracted male migrant workers in India.
In this paper we study the planetary‐scale wave features using concurrent observations of mesospheric wind and temperature, ionospherich'F, and tropospheric wind from Tirunelveli, Gadanki, and ...Kolhapur, all located in the Indian low latitudes, made during February 2009. Our investigations reveal that 3 to 5 day periodicity, characterized as ultrafast Kelvin (UFK) waves, was persistent throughout the atmosphere during this period. These waves show clear signatures of upward wave propagation from troposphere to the upper mesosphere, linking the ionosphere through a clear correlation between mesospheric winds and h'F variations. We also note that the amplitude of this wave decreased as we moved away from the equator. These results are the first of their kind from Indian sector, portraying the vertical as well as latitudinal characteristics of the 3 to 5 day UFK waves simultaneously from the troposphere to the ionosphere.
Key Points
Planetary wave couplings between atmosphere‐ionosphere systems are shown
Signatures of ultrafast Kelvin waves over Indian low latitudes are elaborated
Latitudinal characteristics of UFK waves are shown first time over India
Hydrogeochemical studies were carried out in the Penna-Chitravathi river basins to identify and delineate the important geochemical processes which were responsible for the evolution of chemical ...composition of groundwater. The area is underlain by peninsular gneissic complex of Archaean age, Proterozoic meta-sediments, and strip of river alluvium. Groundwater samples were collected covering all the major hydrogeological environs in pre- and post-monsoon seasons. The samples were analyzed for major constituents such as Ca² ⁺ , Mg² ⁺ , Na ⁺ , K ⁺ , CO₃ ⁻ , HCO₃ ⁻ , Cl ⁻ , SO₂ ⁻ ⁴, NO₃ ⁻ , and F ⁻ . The groundwater in general is of Na ⁺ -Cl ⁻ , Na ⁺ -HCO₃ ⁻ , Ca² ⁺ -Mg² ⁺ -HCO₃ ⁻ , and Ca² ⁺ -Mg² ⁺ -Cl ⁻ types. Na ⁺ among cations and Cl ⁻ and/or HCO₃ ⁻ among anions dominate the water; Na ⁺ and Ca² ⁺ are in the transitional state with Na ⁺ replacing Ca² ⁺ and HCO₃ ⁻ Cl ⁻ due to physiochemical changes in the aquifer and water-rock interactions. The Ca² ⁺ -Mg² ⁺ -Cl ⁻ HCO₃ ⁻ type water in one third samples suggest that ion exchange and dissolution processes are responsible for its origin. Change in storage of aquifer in a season does not influence the major geochemical makeup of groundwater. Gibbs plots indicate that the evolution of water chemistry is influenced by water-rock interaction followed by evapotranspiration process. The aquifer material mineralogy together with semiarid climate, poor drainage system, and low precipitation factors played major role in controlling groundwater quality of the area.
Using a Mesosphere Stratosphere Troposphere (MST) radar, operating at 53
MHz at Gadanki (13.5°N, 79.2°E), India, the present study reports on the temporal and spatial characteristics of ...inertia-gravity waves (IGWs) generated from four tropical cyclones that formed over the Bay of Bengal. IGWs are observed with intrinsic frequencies, vertical and horizontal wavelengths in the ranges of 1.2
f–3.0
f, 2.5–5, and 300–1600
km, respectively, where
f is the Coriolis frequency at the Gadanki site. It is found that both the convective and geostrophic adjustment processes in the troposphere play a major role in the generation of IGWs. Also it is found that the horizontal propagation direction of IGWs is aligned along the motion of convective rain bands.
► We examine the MST radar observation of cyclones generated inertia-gravity waves. ► These four Bay of Bengal cyclones: TC03B, FANOOS, KHAI_MUK and NISHA are considered. ► Lower atmospheric winds during these four cyclones show cyclonic structures. ► Hodograph analysis of the inertia-gravity waves tracks the movement of cyclones. ► The inertia-gravity waves propagate normal outward from the cyclones as expected.
The north eastern part of Anantapur district is in the state of Andhra Pradesh, India, is significant as it is covered by varied geological formations and has different land use and irrigation ...practices. Though ground water is the major drinking water source, deterioration in its quality is going unchecked. In such agro-economy based rural areas, the nitrate contamination is rampant and much attention has not been drawn towards this anthropogenic pollution. In the study area ground water samples from different hydrogeological set-up have been collected during the pre and post monsoon seasons and analysed for the major ions such as Ca, Mg, Na, K, CO₃, HCO₃, Cl, SO₄, NO₃ and F. The study revealed that 65% of the samples were found to be unsuitable for drinking purposes in the pre monsoon season and 45% in the post monsoon due to excess nitrate (>45 mg/l) content in the ground water. Among the different seasons and environs, nitrate was in highest concentration in the granitic terrain and canal command areas during pre monsoon season. The nitrate was found to decrease with depth in all the hydrogeological set-ups in both the seasons. Intense agriculture practices, improper sewerage and organic waste disposal methods were observed to contribute nitrate to the shallow and moderately deep aquifers.
Daily rainfall datasets of 10 years (1998–2007) of Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) version 6 and India Meteorological Department (IMD) gridded ...rain gauge have been compared over the Indian landmass, both in large and small spatial scales. On the larger spatial scale, the pattern correlation between the two datasets on daily scales during individual years of the study period is ranging from 0.4 to 0.7. The correlation improved significantly (~0.9) when the study was confined to specific wet and dry spells each of about 5–8 days. Wavelet analysis of intra-seasonal oscillations (ISO) of the southwest monsoon rainfall show the percentage contribution of the major two modes (30–50 days and 10–20 days), to be ranging respectively between ~30–40% and 5–10% for the various years. Analysis of inter-annual variability shows the satellite data to be underestimating seasonal rainfall by ~110 mm during southwest monsoon and overestimating by ~150 mm during northeast monsoon season.
At high spatio-temporal scales, viz., 1° ×1° grid, TMPA data do not correspond to ground truth. We have proposed here a new analysis procedure to assess the minimum spatial scale at which the two datasets are compatible with each other. This has been done by studying the contribution to total seasonal rainfall from different rainfall rate windows (at 1 mm intervals) on different spatial scales (at daily time scale). The compatibility spatial scale is seen to be beyond 5°×5° average spatial scale over the Indian landmass. This will help to decide the usability of TMPA products, if averaged at appropriate spatial scales, for specific process studies, e.g., cloud scale, meso scale or synoptic scale.
•Diagnostic investigation of an extreme rainfall event is carried out over central and Northern Indian region.•Implication of tropical-extratropical interactions to severe weather is highlighted.•The ...role of dynamical and thermodynamical instabilities in triggering the extreme event is discussed.
A diagnostic investigation of an extreme rainfall episode that occurred over the central and north Indian region is carried out in this study using data from a suite of observations from space-borne instruments and the reanalysis datasets. This event is unique in the sense that the organized tropical and extratropical forcing stimulated the intense rainfall on 01 Jan 2012. The WindSat (multi-frequency polarimetric microwave radiometer) observations indicate the source of the moisture flux coming from the adjoining tropical Ocean. The dynamical and thermo-dynamical contributions are evaluated based on the atmospheric instability analysis using the Atmospheric Infrared Sounder (AIRS) and reanalysis datasets by computing various stability indices such as total totals (TT) index, Potential Vorticity (PV), static stability and the Convective Available Potential Energy (CAPE). High TT index values (>40 K) are observed both in satellite and reanalysis data indicating thermodynamic instability. PV intrusion to low latitudes is also observed with extreme rainfall occurrence ahead of the PV tongue. The vertical structure of PV intrusion shows remarkable features with enhanced upward motions ahead of the intrusion representing the dynamical instability. The reduced static stability, increased CAPE and upper-level cyclonic anomalies together with enhanced moisture in the lower troposphere coming from the adjoining tropical Indian Ocean regulate the amplitude and region of occurrence of the extreme rainfall. Therefore, this study identifies the significant implications of tropical and extra-tropical influences that generate the thermodynamical and dynamical instabilities for the occurrence of the extreme rainfall event over the Central and Northern parts of India.
Objectives
To study the role of hematological parameters in predicting retinopathy of prematurity (ROP) in preterm neonates.
Method
Two hundred forty eight babies less than 34 wk and/or with a birth ...weight of less than 2,000 g were evaluated. Peripheral blood smear and complete blood count were done on day one of life. Ophthalmological examination was done as per guidelines and grades of ROP classified and followed up till 40 wk of gestation for complete vascularisation. Cases were matched with similar number of controls (n = 67) and the sensitivity, specificity and positive predictive value of different parameters were assessed.
Results
The incidence of ROP on screening was found to be 27 %. Sixty seven cases were matched with 67 controls as per birth weight and gestational age. Significant risk factors for ROP included longer duration of ventilation, higher FiO
2
, culture proven sepsis and apnea requiring pharmacotherapy. The incidence of Stage I was 10.5 % (n = 7), Stage II 58.2 % (n = 39) and Stage III was 31.3 % (n = 21). The absolute nucleated RBC (ANRBC) count was found to be the only parameter which was significantly higher in babies with ROP (
p
< 0.001). The ANRBC was higher with increasing severity of ROP (
p
= 0.003). The sensitivity, specificity and positive predictive value of ANRBC with ROP was higher than other parameters.
Conclusions
Increase in ANRBC count correlated with intrauterine hypoxia. Hence, an increase in ANRBC count could be used as a screening tool for the early prediction of ROP in babies.
We report nighttime mesospheric OH and O2 temperature measurements during 21–29 April, 2009, over Gadanki (13.5°N, 79.2°E), India. Large night-to-night variability is observed, which is dominated by ...large amplitudes of short period gravity wave features. It is noted that on 21 and 23 April 2009, the mean nocturnal temperature values for OH emissions altitudes were higher than the O2 emissions, which reversed on 27 April 2009. Further, the wavelet analysis of nighttime mesospehric temperature shows a persistent 35–50min wave for all the durations of observations. In this paper, we discuss the observed variability in the mesospheric OH and O2 temperatures in connection with the passage of convective activity noted over South India along the west coast.
► Large variability in mesospheric OH and O2 temperatures is noted. ► Gravity waves of 35–50min periodicity are found to be dominant. ► Results reveal thermal response of mesosphere to the tropical cyclone, Bijli. ► First data from India to report effects of tropical cyclone on the mesosphere.
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