Studies on atmospheric gravity wave activity in the troposphere and lower stratosphere over a tropical station at Gadanki

MST radars are powerful tools to study the mesosphere, stratosphere and troposphere and have made considerable contributions to the studies of the dynamics of the upper, middle and lower atmosphere. Atmospheric gravity waves play a significant role in controlling middle and upper atmospheric dynamics. To date, frontal systems, convection, wind shear and topography have been thought to be the sources of gravity waves in the troposphere. All these studies pointed out that it is very essential to understand the generation, propagation and climatology of gravity waves. In this regard, several campaigns using Indian MST Radar observations have been carried out to explore the gravity wave activity over Gadanki in the troposphere and the lower stratosphere. The signatures of the gravity waves in the wind fields have been studied in four seasons viz., summer, monsoon, post-monsoon and winter. The large wind fluctuations were more prominent above 10 km during the summer and monsoon seasons. The wave periods are ranging from 10 min-175 min. The power spectral densities of gravity waves are found to be maximum in the stratospheric region. The vertical wavelength and the propagation direction of gravity waves were determined using hodograph analysis. The results show both down ward and upward propagating waves with a maximum vertical wave length of 3.3 km. The gravity wave associated momentum fluxes show that long period gravity waves carry more momentum flux than the short period waves and this is presented

Comparative Study of Plasmodium falciparum and Plasmodium vivax Malaria in Pregnant and Non Pregnant Women in Visakhapatnam, Andhra Pradesh, India

Background: Pregnant women have a higher risk of malaria compared to non-pregnant women. It’s associated with considerable maternal and perinatal morbidity and mortality in developing countries like India. Prevalence of malaria in pregnancy and non pregnant are ranging from 1.7 % to 20 % across India. The Slide Positivity Rate (SPR) for malaria parasite was 17 % for antenatal women in contrast to 8 % among febrile non-pregnant women. Aim: The present study is to compare the clinical features, severity, complications, treatment and outcome of Falciparum/vivax malaria in pregnant and non pregnant women. Methods: Pregnant and non Pregnant women who tested positive for malaria either by microscopy of peripheral blood smear or a quantitative buffy coat (QBC) testeach 100 were enrolled in the study. They were followed up till their delivery and discharge from hospital. Demographic, clinical and laboratory data was collected at enrolment, on event of complication and at delivery. Results: Malaria more common in primi gravida (64 %) and common in second trimester (68 %). Plasmodium falciparum most common causative agent in 60 (60 %) pregnant women and Plasmodium vivax is most common causative agent in 56 (56 %) non-pregnantwomen. Falciparum malaria are more common in primi gravida 40 % than Vivax malaria(16 %). Complications are more common in pregnancy (64 %) group and anemia was commonest complications in both groups. Low Birth weight(LBW) was observed in 46 %. Mortality is higher in pregnant women group (10 %). Conclusion: Malaria andi t’s Complications were more common in pregnant women than non-pregnant. It’s more common in primi gravida and in second trimester. Most common causative agent was Plasmodium falciparum in pregnant women and Plasmodiumvivax in non-pregnant women

Catalytic and recyclability properties of phytogenic copper oxide nanoparticles derived from Aglaia elaeagnoidea flower extract

The phytogenic synthesis method to highly active, recoverable and recyclable heterogeneous copper oxide nanocatalyst and encapsulated within biomaterial that acts as a nontoxic and renewable source of reducing and stabilizing agent. The biosynthesized CuO NPs were characterized using UV–Vis absorption spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and thermo gravimetric analysis-differential scanning calorimetry (TGA–DSC), techniques. The formation of CuO NPs with the size 20–45 nm range is shown in TEM image. Significantly, in aqueous phase CuO NPs have high catalytic activity for the reduction of Congo red (CR), methylene blue (MB) and 4-nitrophenol (4-NP) in the presence of the sodium borohydride (NaBH4) at room temperature. In addition, CuO NPs catalyst can be easily recovered by centrifugation and reused for 6 cycles with more than 90% conversion efficiency. CuO nanocatalyst, leaching after catalytic application was investigated by ICPAES (Inductively coupled plasma atomic emission spectroscopy). CuO NPs possess great prospects in reduction of pernicious dyes and nitro organic pollutants in water

Mean thermal structure of the low-latitude middle atmosphere studied using Gadanki Rayleigh lidar, Rocket, and SABER/TIMED observations

The present study delineates the low-latitude thermal structure in the altitude range of 30 to 110 km using Gadanki (13.5°N, 79.2°E) Rayleigh lidar (1998-2007), Thumba (8.5°N,77°E) rocketsondes (1970-1991), and SABER/TIMED satellite (2002-2007) observations. This study particularly addresses whether (1) the lidar data available only during nighttime is sufficient to study the background mean thermal structure in 30-80 km altitude region, (2) the nonavailability of the lidar data during cloudy seasons (monsoon) will affect the derived background mean thermal structure, and (3) any alternate satellite observations can be used for getting the thermal structure of the middle atmosphere. The comparisons between temperatures measured by Rayleigh lidar and SABER show good agreement, suggesting that SABER data can be used effectively to study the mean thermal structure. The nocturnal average and diurnal average of temperature from SABER show similar features, suggesting that data available from lidar only during nighttime can be effectively used to study the mean background thermal structure between 30 and 80 km. Large difference between SABER and lidar observations during monsoon suggests that low data rate available from the lidar is not sufficient to obtain the mean thermal structure during cloudy seasons. Beside this, variations in stratopause (mesopause) height and temperature are also studied. The stratopause and mesopause lie in the height region of 47-49 km and 97-99 km, with peak temperature of 265 K and 170 K, respectively. Stratopause height and temperature show clear semiannual oscillation. No significant seasonal variation is observed either in mesopause height or in temperature at this low latitude

Long-term MST radar observations of vertical wave number spectra of gravity waves in the tropical troposphere over Gadanki (13.5° N, 79.2° E): comparison with model spectra

The potential utility of Mesosphere-Stratosphere-Troposphere (MST) radar measurements of zonal, meridional and vertical winds for divulging the gravity wave vertical wave number spectra is discussed. The data collected during the years 1995–2004 are used to obtain the mean vertical wave number spectra of gravity wave kinetic energy in the tropical troposphere over Gadanki (13.5° N, 79.2° E). First, the climatology of 3-dimensional wind components is developed using ten years of radar observations, for the first time, over this latitude. This climatology brought out the salient features of background tropospheric winds over Gadanki. Further, using the second order polynomial fit as background, the day-to-day wind anomalies are estimated. These wind anomalies in the 4–14 km height regions are used to estimate the profiles of zonal, meridional and vertical kinetic energy per unit mass, which are then used to estimate the height profile of total kinetic energy. Finally, the height profiles of total kinetic energy are subjected to Fourier analysis to obtain the monthly mean vertical wave number spectra of gravity wave kinetic energy. The monthly mean vertical wave number spectra are then compared with a saturation spectrum predicted by gravity wave saturation theory. A slope of 5/3 is used for the model gravity wave spectrum estimation. In general, the agreement is good during all the months. However, it is noticed that the model spectrum overestimates the PSD at lower vertical wave numbers and underestimates it at higher vertical wave numbers, which is consistently observed during all the months. The observed discrepancies are attributed to the differences in the slopes of theoretical and observed gravity wave spectra. The slopes of the observed vertical wave number spectra are estimated and compared with the model spectrum slope, which are in good agreement. The estimated slopes of the observed monthly vertical wave number spectra are in the range of −2 to −2.8. The significance of the present study lies in using the ten years of data to estimate the monthly mean vertical wave number spectra of gravity waves, which will find their application in representing the realistic gravity wave characteristics in atmospheric models

Climatology of low-latitude mesospheric echo characteristics observed by Indian mesosphere, stratosphere, and troposphere radar

Low-latitude mesospheric echo characteristics are investigated using data collected during June 1994 to July 2005 (11 years) by the Indian mesosphere, stratosphere, and troposphere radar located at Gadanki (13.5°N, 79.2°E). Mesospheric echoes are frequently observed during 1000-1530 hrs (local time) in the height range of 68-78 km and are found to be highly intermittent in both space and time, consistent with those reported elsewhere. Although echoes are observed throughout the year, strong seasonal dependence has been observed in both echo occurrence and signal-to-noise ratio (SNR). Percentage occurrence (PO) of mesospheric echoes shows two maxima, one during late March equinox and early summer, and another during September. However, corresponding SNR suggests that strong echoes occur in both equinoxes with a minimum during winter. A clear semiannual variation is observed in PO of echoes with a peak occurring during the months of May and October. Similar variation is observed in SNR with peaks in March and September-November. These features are quite different from those observed at midlatitudes and high latitudes. Annual oscillation seems to fit well above 78 km and below 68 km, although on many occasions, occurrence of echo is poor at these heights. The ratio of vertical to off-vertical beam SNR (which could be taken as a measure of aspect sensitivity) was close to unity at these heights, indicating that scattering is due to turbulence-generated refractive index fluctuations. A positive correlation (R = 0.37) between PO and solar activity is observed, whereas a negative correlation (R = -0.55) is found between SNR and solar activity. The echo characteristics observed have been compared in detail with those reported from midlatitudes and high latitudes. The mechanisms behind the observed features are discussed in the light of mesospheric temperature inversions (MTIs), which are often noticed at this location, and wave breaking at these altitudes

Soil Moisture Variability in India: Relationship of Land Surface–Atmosphere Fields Using Maximum Covariance Analysis

This study investigates the spatial and temporal variability of the soil moisture in India using Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) gridded datasets from June 2002 to April 2017. Significant relationships between soil moisture and different land surface⁻atmosphere fields (Precipitation, surface air temperature, total cloud cover, and total water storage) were studied, using maximum covariance analysis (MCA) to extract dominant interactions that maximize the covariance between two fields. The first leading mode of MCA explained 56%, 87%, 81%, and 79% of the squared covariance function (SCF) between soil moisture with precipitation (PR), surface air temperature (TEM), total cloud count (TCC), and total water storage (TWS), respectively, with correlation coefficients of 0.65, −0.72, 0.71, and 0.62. Furthermore, the covariance analysis of total water storage showed contrasting patterns with soil moisture, especially over northwest, northeast, and west coast regions. In addition, the spatial distribution of seasonal and annual trends of soil moisture in India was estimated using a robust regression technique for the very first time. For most regions in India, significant positive trends were noticed in all seasons. Meanwhile, a small negative trend was observed over southern India. The monthly mean value of AMSR soil moisture trend revealed a significant positive trend, at about 0.0158 cm3/cm3 per decade during the period ranging from 2002 to 2017