Trends in thermal discomfort indices over western coastal cities of India     

Desai  Manasi S.  Dhorde  Amit G. 《Theoretical and Applied Climatology》2018,131(3-4):1305-1321

Theoretical and Applied Climatology - The present research aimed at analyzing temporal trends in thermal discomfort indices for a period of 46 years from 1969 to 2014 over western coastal...  相似文献   

A Numerical Case Study of the Implications of Secondary Circulations to the Interpretation of Eddy-Covariance Measurements Over Small Lakes     

William T. Kenny  Gil Bohrer  Timothy H. Morin  Chris S. Vogel  Ashley M. Matheny  Ankur R. Desai 《Boundary-Layer Meteorology》2017,163(2):311-326

The CASES-99 experimental data are used to analyze turbulence behaviour under a range of stable conditions using an adaptive method based on Hilbert spectral analysis. The characteristic scales of intrinsic mode functions vary between different stratifications. The second-order Hilbert marginal spectra display clear separation between fine-scale turbulence and large-scale motions. After removing the large-scale motions, the statistical characteristics of the reconstructed signals confirm the distinction of different stratifications in the fine-scale range. The correlation coefficient analyses reveal that the Hilbert spectral analysis method separates turbulence from large-scale motions in the stable boundary layer.  相似文献   

Monitoring Measurements from the Jason-1 Microwave Radiometer and Independent Validation with GPS   总被引：1，自引：0，他引：1  

Shailen D. Desai  Bruce J. Haines 《Marine Geodesy》2004,27(1):221-240

The Jason-1 Microwave Radiometer (JMR) provides measurements of the wet troposphere content to correct the altimetric range measurement for the associated path delay. Various techniques are used to monitor the JMR wet troposphere path delays, with measurements of zenith troposphere content from terrestrial GPS sites used as an independent verification technique. Results indicate that an unexpected offset of approximately +4.1 ± 1.2 mm (drier) emerged in the JMR measurements of wet path delay between cycles 28-32 of the Jason-1 mission, and that the measurements may be drifting at a rate of approximately -0.5 mm/year. These anomalies are shown to be caused by a -0.7 K offset in 23.8 GHz brightness temperatures between cycles 28-32, and a 0.16 ± 0.04 and -0.45 ± 0.08 K/year drift in the 18.7 and 34.0 GHz brightness temperatures, respectively. Intercomparison of the 3-Hz JMR brightness temperature measurements show that they have been drifting with respect to each other, and that a dependence on yaw-steering regime is present in these measurements. An offset of 0.5 m/s between cycles 28-32 and a drift of approximately 0.5 m/s/year in the JMR wind speed measurements is also associated with these anomalies in the 1-Hz brightness temperatures. These errors in JMR wind speeds presently have a negligible impact on the retrieved JMR path delays.  相似文献   

Dynamics of dissolved organic carbon in the northwestern Indian Ocean     

M. Dileep Kumar  A. Rajendran  K. Somasundar  B. Haake  A. Jenisch  Z. Shuo  V. Ittekkot  B.N. Desai 《Marine Chemistry》1990,31(1-3)

We report here the non-conservative behaviour of DOC in the northwestern Indian Ocean by studying this parameter together with other carbon and nitrogen components. This contrasts with earlier reports of conservative behaviour. Concentrations of DOC, 3–4 times higher than those reported earlier, were found to decrease northward from the equator. Total carbon dioxide (TCO₂) increases in proportion of the oxygen utilized, thus revealing the dominant biological role in the carbon turnover. The CO₂ added through dissolution of biogenic debris is found to decrease southward, in general. Decomposition of organic material contributes at least 64% to the CO₂ addition that increases southward, the rest being from dissolution of skeletal material. Evidence is provided for the utilization of oxygen and nitrate for DOC oxidative decomposition. Accumulation of DOC without its complete oxidation to CO₂ could be the main reason for the TCO₂ decrease in southern Arabian Sea. Relationships of DOC with nitrification and denitrification processes show that the microbial population plays a major role in regulating the DOC contents in the seawater of this region. Consumption/decomposition by denitrifying bacteria and other micro-organisms responsible for nitrogen cycling in the sea are found to be intimately related to the DOC dynamics and are responsible for decreased DOC concentrations in the north. DOC accumulation in the southern Arabian Sea seems to facilitate bacterio-particulate aggregate formation and consequent nitrification, which results in excess nitrate. Application of a one-dimensional advection-diffusion model to the present data set provides evidence for the non-conservative nature of DOC in the Arabian Sea.  相似文献   

Imaging Fabry-Pérot observations of [OI] 6300 Å emission in the coma of Halley's comet 1982i     

C. Debi Prasad  J. N. Desai 《Earth, Moon, and Planets》1989,44(2):191-195

The observation of [OI] 6300 » emission in the coma of Halley's comet 1982i, using the imaging Fabry-Pérot spectrometer, was carried out from Gurushikhar (2439N, 7243E, 1700m altitude), Mt. Abu, India on March 15, 1986 (R = 0.90 AU, = 0.96 AU). The analysis of the interferogram show the absence of the differential velocity of neutral oxygen above 5 km s^–1.  相似文献   

In situ Observations of CIRs on STEREO,Wind, and ACE During 2007 – 2008     

Mason  G. M.  Desai  M. I.  Mall  U.  Korth  A.  Bucik  R.  von Rosenvinge  T. T.  Simunac  K. D. 《Solar physics》2009,256(1-2):393-408

During the 2007 and 2008 solar minimum period, STEREO, Wind, and ACE observed numerous Corotating Interaction Regions (CIRs) over spatial separations that began with all the spacecraft close to Earth, through STEREO separation angles of ～?80 degrees in the fall of 2008. Over 35 CIR events were of sufficient intensity to allow measurement of He and heavy ion spectra using the IMPACT/SIT, EPACT/STEP and ACE/ULEIS instruments on STEREO, Wind, and ACE, respectively. In addition to differences between the spacecraft expected on the basis of simple corotation, we observed several events where there were markedly different time-intensity profiles from one spacecraft to the next. By comparing the energetic particle intensities and spectral shapes along with solar wind speed we examine the extent to which these differences are due to temporal evolution of the CIR or due to variations in connection to a relatively stable interaction region. Comparing CIRs in the 1996?–?1997 solar minimum period vs. 2007?–?2008, we find that the 2007?–?2008 period had many more CIRs, reflecting the presence of more high-speed solar wind streams, whereas 1997 had almost no CIR activity.

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An analytic representation of the three-dimensional structure of monsoon depressions     

S. K. Mishra  D. R. Chakraborty  S. S. Desai 《Meteorology and Atmospheric Physics》1982,31(4):329-337

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Mercury in Thana Creek,Bombay Harbour     

M.D. Zingde  B.N. Desai 《Marine pollution bulletin》1981,12(7):237-241

Mercury content of the water column estimated along Thana Creek/Bombay Harbour gave a standing stock of about 77 kg in excess of the expected background. Mercury concentration in sediment from 23 locations which varied from 0.17 to 8.21 ppm (dry weight) with marked increase from the harbour to the creek region suggests substantial mercury input in the head region. Chemical extraction by hydrogen peroxide indicated that more than 70% of mercury was leachable and probably organically bound. The mercury enriched layer in the sediment cores was about 10–25 cm in the creek region and 0–8 cm in the harbour area. The data has been used to calculate an excess of 14 tonnes of mercury over the natural background. Analysis of a few zooplankton and benthic samples from the creek region gave indication of bioaccumulation of mercury.  相似文献   

Drought forecasting using stochastic models   总被引：8，自引：4，他引：8  

A. K. Mishra  V. R. Desai 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(5):326-339

Drought is a global phenomenon that occurs virtually in all landscapes causing significant damage both in natural environment and in human lives. Due to the random nature of contributing factors, occurrence and severity of droughts can be treated as stochastic in nature. Early indication of possible drought can help to set out drought mitigation strategies and measures in advance. Therefore drought forecasting plays an important role in the planning and management of water resource systems. In this study, linear stochastic models known as ARIMA and multiplicative Seasonal Autoregressive Integrated Moving Average (SARIMA) models were used to forecast droughts based on the procedure of model development. The models were applied to forecast droughts using standardized precipitation index (SPI) series in the Kansabati river basin in India, which lies in the Purulia district of West Bengal state in eastern India. The predicted results using the best models were compared with the observed data. The predicted results show reasonably good agreement with the actual data, 1–2 months ahead. The predicted value decreases with increase in lead-time. So the models can be used to forecast droughts up to 2 months of lead-time with reasonably accuracy.  相似文献   

Earthquake analysis with generalized plasticity model for saturated soils     

C. S. Desai  H. M. Galagoda 《地震工程与结构动力学》1989,18(6):903-919

A plasticity based constitutive model for anisotropic behaviour of soils is implemented in a finite element procedure based on the generalized Biot theory for the dynamic non-linear response of porous materials. The model represents a version in the hierarchical approach of constitutive modelling and allows for inelastic response during loading, unloading and reloading. The procedure has been verified previously with respect to closed-form solutions for wave propagation in porous media. In this paper, it is used to predict the behaviour of a realistic structure-saturated porous soil system subjected to earthquake loading. Both linear and non-linear analyses have been performed. It has been found that the predicted responses from the two analyses are significantly different; for example, in comparison with the linear analysis the non-linear response shows increased magnitudes and zones of concentration of pore water pressures, increased magnitudes of horizontal displacements, decreased magnitudes of vertical displacements and increased magnitudes of shear stresses.  相似文献