Doppler SODAR observations of the temperature structure parameter during monsoon season over a tropical rural station,Gadanki     

M SHRAVAN KUMAR  V K ANANDAN  AMIT KESARKAR  P NARASIMHA REDDY 《Journal of Earth System Science》2011,120(1):65-72

Doppler SODAR (Sound Detection and Ranging) measurements over a tropical Indian station at National Atmospheric Research Laboratory (NARL), Gadanki (13.5°N, 79.2°E) during two consecutive monsoon seasons, 2007 and 2008, are investigated to study the influence of mechanically generated turbulence on temperature structure parameter (C_T²)_{\rm T}^{2}) in the convective boundary layer. Increase in the C_T²_{\rm T}^{2} is observed after the arrival of monsoon for both seasons. Contribution of vertical wind shear in horizontal wind component to C_T²_{\rm T}^{2} due to zonal winds is responsible for the increase observed in the temperature structure parameter which is inferred from the results obtained. C_T²_{\rm T}^{2} is found to be increased by an order of 2 in both the lower and upper altitudes, respectively. Magnitude of wind speed is reported to be doubled with the arrival of monsoon. It is also observed that, southwest monsoon wind modulates the day-to-day variations of wind pattern over this station during the onset phase of monsoon season. The lower variability observed at lower height is attributed to the complex topography surrounding this region.  相似文献   

Impact of additional surface observation network on short range weather forecast during summer monsoon 2008 over Indian subcontinent   总被引：1，自引：0，他引：1  

PRASHANT KUMAR  RANDHIR SINGH  P C JOSHI  P K PAL 《Journal of Earth System Science》2011,120(1):53-64

The three dimensional variational data assimilation scheme (3D-Var) is employed in the recently developed Weather Research and Forecasting (WRF) model. Assimilation experiments have been conducted to assess the impact of Indian Space Research Organisation’s (ISRO) Automatic Weather Stations (AWS) surface observations (temperature and moisture) on the short range forecast over the Indian region. In this study, two experiments, CNT (without AWS observations) and EXP (with AWS observations) were made for 24-h forecast starting daily at 0000 UTC during July 2008. The impact of assimilation of AWS surface observations were assessed in comparison to the CNT experiment. The spatial distribution of the improvement parameter for temperature, relative humidity and wind speed from one month assimilation experiments demonstrated that for 24-h forecast, AWS observations provide valuable information. Assimilation of AWS observed temperature and relative humidity improved the analysis as well as 24-h forecast. The rainfall prediction has been improved due to the assimilation of AWS data, with the largest improvement seen over the Western Ghat and eastern India.  相似文献   

Development of regional wheat VI-LAI models using Resourcesat-1 AWiFS data     

SASMITA CHAURASIA  R NIGAM  B K BHATTACHARYA  V N SRIDHAR  K MALLICK  S P VYAS  N K PATEL  J MUKHERJEE  CHANDER SHEKHAR  DHIRAJ KUMAR  K R P SINGH  G D BAIRAGI  N L PUROHIT  J S PARIHAR 《Journal of Earth System Science》2011,120(6):1113-1125

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Simulations of Eurasian Winter Temperature Trends in Coupled and Uncoupled CFSv2     

Thomas W.COLLOW  Wanqiu WANG  Arun KUMAR 《大气科学进展》2018,35(1):14-26

Conflicting results have been presented regarding the link between Arctic sea-ice loss and midlatitude cooling, particularly over Eurasia. This study analyzes uncoupled(atmosphere-only) and coupled(ocean–atmosphere) simulations by the Climate Forecast System, version 2(CFSv2), to examine this linkage during the Northern Hemisphere winter, focusing on the simulation of the observed surface cooling trend over Eurasia during the last three decades. The uncoupled simulations are Atmospheric Model Intercomparison Project(AMIP) runs forced with mean seasonal cycles of sea surface temperature(SST)and sea ice, using combinations of SST and sea ice from different time periods to assess the role that each plays individually,and to assess the role of atmospheric internal variability. Coupled runs are used to further investigate the role of internal variability via the analysis of initialized predictions and the evolution of the forecast with lead time.The AMIP simulations show a mean warming response over Eurasia due to SST changes, but little response to changes in sea ice. Individual runs simulate cooler periods over Eurasia, and this is shown to be concurrent with a stronger Siberian high and warming over Greenland. No substantial differences in the variability of Eurasian surface temperatures are found between the different model configurations. In the coupled runs, the region of significant warming over Eurasia is small at short leads, but increases at longer leads. It is concluded that, although the models have some capability in highlighting the temperature variability over Eurasia, the observed cooling may still be a consequence of internal variability.  相似文献   

Multiyear Observations of Deposition-Mode Ice Nucleating Particles at Two High-Altitude Stations in India     

Sandeep D. WAGH  Baban NAGARE  Sanjay D. MORE  P. Pradeep KUMAR 《大气科学进展》2017,34(12):1437-1446

Ice nucleating particle(INP) measurements were made at two high-altitude stations in India. Aerosols collected on filter paper at Girawali Observatory, Inter University Center for Astronomy Astrophysics(IGO), and at the Radio Astronomy Center, Ooty(RAC), were activated in deposition mode using a thermal gradient diffusion chamber to determine the INP concentrations. The measurement campaigns at IGO were conducted during 2011, 2013 and 2014, and at RAC during 2013 and 2014. When the aerosol samples were exposed to an ice supersaturation of between 5% and 23% in the temperature range~(-1)7.6?C to-22?C, the maximum INP number concentration at IGO and RAC was 1.0 L~(-1) and 1.6 L~(-1), respectively.A maximum correlation coefficient of 0.76 was observed between the INP number concentration and ice supersaturation. The airmass trajectories analyzed for the measurement campaigns showed that the Arabian Desert and arid regions were the main INP contributors. Elemental analysis of particles showed the presence of Na, Cl, Si, Al, Fe, Cu, Co, Cd, S, Mn and K, as well as some rare-Earth elements like Mo, Ru, La, Ce, V and Zr. When aerosols in the size range 0.5–20 μm were considered, the fraction that acted as INPs was 1 : 10~4 to 1 : 10~6 at IGO, and 1 : 10~3 to 1 : 10~4 at RAC. The higher ratio of INPs to aerosols at RAC than IGO may be attributable to the presence of rare-Earth elements observed in the aerosol samples at RAC, which were absent at IGO.  相似文献   

Nodular features from Proterozoic Sonia Sandstone, Jodhpur Group, Rajasthan: A litho-biotectonic perspective     

ARVIND SINGH  VIKASH ANAND  PRABHAS PANDEY  PARTHA PRATIM CHAKRABORTY 《Journal of Earth System Science》2013,122(2):309-320

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Existence of torsional surface waves in an earth’s crustal layer lying over a sandy mantle     

SUMIT KUMAR VISHWAKARMA  SHISHIR GUPTA 《Journal of Earth System Science》2013,122(5):1411-1421

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Insights into the P–T evolution path of Tso Morari eclogites of the north-western Himalayas: Constraints on the geodynamic evolution of the region     

PREETI SINGH  ASHIMA SAIKIA  NARESH CHANDRA Pant  PRAMOD KUMAR VERMA 《Journal of Earth System Science》2013,122(3):677-698

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Carbon dioxide emissions from fossil-fuel use, 1751–1950     

R. J. ANDRES  D. J. FIELDING  G. MARLAND  T. A. BODEN  N. KUMAR  A. T. KEARNEY 《Tellus. Series B, Chemical and physical meteorology》1999,51(4):759-765

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Prediction and error growth in the daily forecast of precipitation from the NCEP CFSv2 over the subdivisions of Indian subcontinent     

DHRUVA KUMAR PANDEY  SHAILENDRA RAI  A K SAHAI  S ABHILASH  N K SHAHI 《Journal of Earth System Science》2016,125(1):29-45

This study investigates the forecast skill and predictability of various indices of south Asian monsoon as well as the subdivisions of the Indian subcontinent during JJAS season for the time domain of 2001–2013 using NCEP CFSv2 output. It has been observed that the daily mean climatology of precipitation over the land points of India is underestimated in the model forecast as compared to observation. The monthly model bias of precipitation shows the dry bias over the land points of India and also over the Bay of Bengal, whereas the Himalayan and Arabian Sea regions show the wet bias. We have divided the Indian landmass into five subdivisions namely central India, southern India, Western Ghat, northeast and southern Bay of Bengal regions based on the spatial variation of observed mean precipitation in JJAS season. The underestimation over the land points of India during mature phase was originated from the central India, southern Bay of Bengal, southern India and Western Ghat regions. The error growth in June forecast is slower as compared to July forecast in all the regions. The predictability error also grows slowly in June forecast as compared to July forecast in most of the regions. The doubling time of predictability error was estimated to be in the range of 3–5 days for all the regions. Southern India and Western Ghats are more predictable in the July forecast as compared to June forecast, whereas IMR, northeast, central India and southern Bay of Bengal regions have the opposite nature.  相似文献