Seasonal relationships between Indian summer monsoon rainfall and the Southern Oscillation.

Association between the all-India summer monsoon (June to September) rainfall and an index of the Southern Oscillation (SO) is studied in relation to the vagaries of the monsoon rainfall and the seasonal characteristics of the SO. The SOI values of different months and standard seasons show opposite tendencies during deficient and excess years of all-India monsoon rainfall. The correlation coefficients between the all-India monsoon rainfall series and the SOIs of summer monsoon, autumn and winter minus spring seasons are significant at the 1 per cent level

Spatial variability of aridity oyer northern India

Spatial variability of aridity over northern India (north of 20°N) is studied by examining variations in the arid area. Area with an objectively determined summer monsoon rainfall (June to September total) of less than 500 mm is identified as arid area. The summer monsoon rainfall of 212 rain-gauges from 212 districts of the region for the period 1871-1984 are used in the analysis. An interesting feature of the arid area series is that it shows decreasing trend from beginning of the present century. The summer monsoon rainfall fluctuations over five subjectively divided zones over northern India are examined to understand the association between rainfall and the arid area variations. The rainfall series for northwest India shows a significant increasing trend and that for northeast India a significant decreasing trend from the beginning of this century. Rainfall fluctuations over the remaining zones can be considered intermediate stages of a systematic spatial change in the rainfall pattern. This suggested that the recent decreasing trend in the arid area is due to a westward shift in the monsoon rainfall activities. From correlation analyses it is inferred that perhaps the recent decreasing trend in the arid area and increasing trend in the monsoon rainfall over northwest India are associated with a warming trend of the northern hemisphere

Scale-size calculations, energy dissipation rates and height coverage of a 404 MHz wind profiler at IMD, Pune

The 404 MHz wind profiler at the India Meteorological Department, Pune, is the first wind profiler of this frequency in India. Therefore, it is necessary to achieve maximum possible height to get valuable data. UHF wind profilers have better height and time resolution, which enables us to make reliable and correct estimations of the wind at various altitudes at regular spacing above the observational site. The height coverage of the profiler depends upon various factors like power aperture product and the operating wavelength vis-avis scale sizes available in the atmosphere. In this study, daily averaged second moment data archived during clear-air conditions have been used to estimate the scale-size parameters in terms of eddy dissipation rates, which explicitly indicates that more height coverage of a profiler depends only on the availability of the scale sizes in the atmosphere to which the radar is sensitive, and that in turn depends on where in the inertial subrange the operating wavelength resides. Power aperture product at various C2n values has been estimated. This note explicitly explains why the height coverage of the wind profiler at Pune is limited to 6-8 km under clear-air conditions

The 404 MHZ wind profiler to observe precipitation

This article delineates the tropical precipitation and classification of precipitating systems into stratiform and convective type, using the UHF wind profiler located at the Indian tropical station Pune (18°32'N, 73°51'E). Under moderate rain conditions the two signals arising due to clear air motions and precipitation are clearly distinguished in the power spectra. An algorithm with suitable methodology has been developed that separates clear air and precipitation echoes when they are clearly distinguishable as seen in the power spectrum. This was tested for various power spectra and found to work well under moderate rain conditions. The sensitivity of the threshold was tested for the precipitation observed on 25 July 2005. In addition, case studies of stratiform rain (precipitation observed over the site on 26 July 2005, 0800 h IST) and convective system (a thunderstorm observed on 16 May 2004) are presented and discussed. An attempt has been made to fit a Gaussian distribution curve to determine the actual Doppler shift and spectral width. The observed convective and stratiform precipitation is described in terms of reflectivity, maximum spectral width and Doppler velocity gradient in the vertical

An ocean-atmosphere index for ENSO and its relation to Indian monsoon rainfall

An Ocean-Atmosphere Index (OAI) for ENSO is developed using data on Southern Oscillation Index (SOI) and sea surface temperature (SST) over eastern equatorial Pacific. Seasonal values of OAI, SOI and SST have been computed for the seasons September-October-November (SON), December-JanuaryFebruary (DJF), March-April-May (MAM) and June-July-August (JJA). Similarly SON to DJF, DJF to MAM, MAM to JJA and JJA to SON tendencies have been worked out for SOI, SST and OAI. The relationships between Indian Monsoon Rainfall (IMR) and SOI/SST/OAI, (i) for the seasons SON, DJF and MAM before and after the monsoon and JJA concurrent with the monsoon and (ii) for SON to DJF and DJF to MAM tendencies before and after the monsoon, and MAM to JJA tendency concurrent with the monsoon have been explored. It is found that IMR is more influenced by SOI before the monsoon than it is influenced by SST before the monsoon and IMR affects SST after monsoon more strongly than it affects SOI after the monsoon. It is also observed that DJF to MAM tendencies for SOI, SST and OAI before monsoon are significantly related to IMR, among which the relationship between IMR and DJF to MAM tendency for OAI is the best

Seasonal, annual and inter-annual features of turbulence parameters over the tropical station Pune (18°32' N, 73°51' E) observed with UHF wind profiler

The present study is specifically focused on the seasonal, annual and inter-annual variations of the refractive index structure parameter (Cn2) using three years of radar observations. Energy dissipation rates (ε) during different seasons for a particular year are also computed over a tropical station, Pune. Doppler spectral width measurements made by the Wind Profiler, under various atmospheric conditions, are utilized to estimate the turbulence parameters. The refractive index structure parameter varies from 10−17.5 to 10−13 m−2/3 under clear air to precipitation conditions in the height region of 1.05 to 10.35 km. During the monsoon months, observed Cn2 values are up to 1–2 orders of magnitude higher than those during pre-monsoon and post-monsoon seasons. Spectral width correction for various non-turbulent spectral broadenings such as beam broadening and shear broadening are made in the observed spectral width for reliable estimation of ε under non-precipitating conditions. It is found that in the lower tropospheric height region, values of ε are in the range of 10−6 to 10−3 m2 s−3. In summer and monsoon seasons the observed values of ε are larger than those in post-monsoon and winter seasons in the lower troposphere. A comparison of Cn2 observed with the wind profiler and that estimated using Radio Sonde/Radio Wind (RS/RW) data of nearby Met station Chikalthana has been made for the month of July 200

The Impact of Antiretroviral Therapy in a Cohort of HIV Infected Patients Going in and out of the San Francisco County Jail

BackgroundJails are an important venue of HIV care and a place for identification, treatment and referral for care. HIV infected inmates in the San Francisco County jail are offered antiretroviral treatment (ART), which many take only while in jail. We evaluated the effect of ART administration in a cohort of jail inmates going in and out of jail over a nine year period.Methodology/Principal FindingsIn this retrospective study, we examined inmates with HIV going in and out of jail. Inmates were categorized by patterns of ART use: continuous ART - ART both in and out of jail, [...] more likely to have higher VL than inmates on continuous ART. Furthermore, Inmates on intermittent ART and never-on ART lost 1.60; 95%CI (1.06, 2.13) and 1.97; 95%CI (0.96, 3.00) more CD4 cells per month, respectively, compared to continuously treated inmates. The continuous ART inmates gained 0.67CD4 cells/month.Conclusions/SignificanceContinuous ART therapy in jail inmate's benefits CD4 cell counts and control of VL especially compared to those who never took ART. Although jail inmates on intermittent ART were more likely to lose CD4 cells and experience higher VL over time than those on continuous ART, CD4 cell loss was slower in these inmates as compared to inmates never on ART. Further studies are needed to evaluate whether or not intermittent ART provides some benefit in outcome if continuous ART is not possible or likely

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO