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1.
A. Chakraborty H. C. Upadhyaya O. P. Sharma S. K. Deb 《Meteorology and Atmospheric Physics》2003,83(3-4):221-236
Summary ?A newly developed ocean general circulation model has been tested and verified with some idealized experiments. Generally
two types of idealized experiments have been done here. First types are called as “symmetric experiments” and second types
are called as “transport experiments”. The first types of experiment help to correct the model core and any deficiency from
boundary conditions. The second types of experiment are the type of validation experiment. In both the experiments there are
no continents, so in the first type of experiments where symmetric forcings are provided one can expect that model should
maintain the symmetric nature. In the second type of experiments one can expect that model should respond correctly to the
wind forcings, if no wind curl is present in the wind forcing there will be no circulation in the extratropics and if there
is no wind the equator there will be no circulation. The model reproduces the possible envisaged results of these experiments
and gives the confidence for performing the realistic integration.
Received February 20, 2002; accepted July 7, 2002
Published online: February 20, 2003 相似文献
2.
Assessment of groundwater potential zone using remote sensing,GIS and multi criteria decision analysis techniques 总被引:1,自引:0,他引:1
D. C. Jhariya Tarun Kumar M. Gobinath Prabhat Diwan Nawal Kishore 《Journal of the Geological Society of India》2016,88(4):481-492
The sustainable development and management of groundwater resource needs quantitative assessment, based on scientific principle and recent techniques. In the present study, groundwater potential zone is being determined using remote sensing, Geographical Information System (GIS) and Multi-Criteria Decision Analysis (MCDA) techniques using various thematic layers viz. geomorphology, geology, drainage density, slope, rainfall, soil texture, groundwater depth, soil depth, lineament and land use/ land cover. The Analytic Hierarchy Approach (AHP) is used to determine the weights of various themes for identifying the groundwater potential zone based on weights assignment and normalization with respect to the relative contribution of the different themes to groundwater occurrence. Finally, obtained groundwater potential zones were classified into five categories, viz. low, medium, medium-high, high and very high potential zone. The result depicts the groundwater potential zone in the study area and found to be helpful in better development and management planning of groundwater resource. 相似文献
3.
Hashmi Fatima H. C. Upadhyaya S. N. Tripathi O. P. Sharma Fangqun Yu 《Meteorology and Atmospheric Physics》2011,112(3-4):101-115
A significant fraction of the total number of particles present in the atmosphere is formed by nucleation in the gas phase. Nucleation and the subsequent growth process influence both number concentration of particles and their size distribution besides chemical and optical properties of atmospheric aerosols. Sulphate aerosol nucleation mechanisms promoted by ions have been evaluated here in a tropospheric interactive chemistry-aerosol module for mass and number concentration in a global atmospheric model. The indirect radiative forcing of sulphate particles is assessed in this model; indirect radiative forcing is different for ion-induced (IIN) and ion-mediated (IMN) mechanisms. The indirect radiative forcing in 10-year simulation runs has been calculated as ?1.42?W/m2 (IIN) and ?1.54?W/m2 (IMN). The 5% emission of primary sulphate particles in simulations changes the indirect radiative forcing from ?1.42 to ?1.44?W/m2 for IIN case, and from ?1.54 to ?1.55 W/m2 for the IMN case. More precisely, owing to greater nucleation rates, IMN mechanisms produces greater cooling than the IIN mechanisms in the backdrop that both mechanisms produce almost identical distribution of CDNC in their pre-industrial runs. The inclusion of primary particles in simulations with IIN and IMN mechanisms increases both CDNC and the indirect radiative forcing. 相似文献
4.
The main advantages of constant potential enthalpy as a vertical coordinate are weaker horizontal velocity gradients in frontal
regions and a higher vertical resolution. A disadvantage is the intersection of isentropes with the ground and folding of
these surfaces. A numerical model is proposed to overcome the difficulties imposed by the intersection of isentropes with
the ground. The model contains a physical and computational domain. The top and bottom surfaces of the computational domain
are isentropes whereas the physical domain of the flow confined above by a free surface of constant pressure, and the bottom
of this domain is the surface of the earth. In the present study the top surfaces of these two domains coincide (θ
T, PTare constants in space and time). The model was tested for the study of frontogenesis and cyclogenesis and integrated for
7 days. The results correspond to enstrophy-conserving finite difference scheme. 相似文献
5.
S. K. Deb H. C. Upadhyaya O. P. Sharma A. Chakraborty 《Meteorology and Atmospheric Physics》2006,94(1-4):43-64
Summary Hindcasts for the Indian summer monsoons (ISMs) of 2002 and 2003 have been produced from an ensemble of numerical simulations
performed with a global model by changing SST. Two sets of ensemble simulations have been produced without vegetation: (i)
by prescribing the weekly observed SST from ECMWF (European Centre for Medium Range Weather Forecasting) analyses, and (ii)
by adding weekly SST anomalies (SSTA) of April to the climatological SST during the simulation period from May to August.
For each ensemble, 10 simulations have been realized with different initial conditions that are prepared from ECMWF data with
five each from April and May analyses of both the years. The predicted June–July monsoon rainfall over the Indian region shows
good agreement with the GPCP (observed) pentad rainfall distribution when 5 member ensemble is taken from May initial conditions.
The All-India June–July simulated rainfall time series matches favourably with the observed time series in both the years
for the five member ensemble from May initial condition but drifts away from observation with April initial conditions. This
underscores the role of initial conditions in the seasonal forecasting. But the model has failed to capture the strong intra-seasonal
oscillation in July 2002. Heating over equatorial Indian Ocean for June 2002 in a particular experiment using 29th May 12
GMT as initial conditions shows some intra-seasonal oscillation in July 2002 rainfall, as in observation. Further evaluation
of the seasonal simulations from this model is done by calculating the empirical orthogonal functions (EOFs) of the GPCP rainfall
over India. The first four EOFs explain more than 80% of the total variance of the observed rainfall. The time series of expansion
coefficients (principal components), obtained by projecting on the observed EOFs, provide a better framework for inter-comparing
model simulations and their evaluation with observed data. The main finding of this study is that the All-India rainfall from
various experiments with prescribed SST is better predicted on seasonal scale as compares to prescribed SST anomalies. This
is indicative of a possible useful seasonal forecasts from a GCM at least for the case when monsoon is going to be good. The
model responses do not differ much for 2002 and 2003 since the evolution of SST during these years was very similar, hence
July rainfall seems to be largely modulated by the other feedbacks on the overall circulation. 相似文献
6.
Summary The adjoint technique has been widely used over the last two decades in applications involving the dynamics of the Atmosphere
and Ocean. This present study applies this technique in the assimilation of oceanic parameters such as temperature and net-surface
heat flux, in a variable resolution Ocean General Circulation Model (OGCM). The National Center for Environmental Prediction
(NCEP) 1999 July–August global data (sea-surface temperature and derived surface heat flux) and vertical temperature profiles
collected from ORV Sagar Kanya and INS Sagardhwani during the Bay of Bengal Monsoon Experiment (BOBMEX 1999) are used for
assimilation over the Bay of Bengal. The net-surface heat flux and temperature obtained after assimilation show good agreement
with their respective seasonal patterns over the whole Indian Ocean, though there are some differences in the numerical values
of heat fluxes. The vertical profiles of temperature after assimilation over the Bay of Bengal show strong resemblance with
the corresponding ship observations, emphasizing the importance of the adjoint technique in ocean data assimilation. 相似文献
7.
8.
S. K. Deb H. C. Upadhyaya O. P. Sharma J. Y. Grandpeix 《Pure and Applied Geophysics》2007,164(8-9):1667-1681
A new analytical formulation of entrainment and detrainment in the Tiedtke's mass flux cumulus parameterization is presented
here in which cloud height is one of the key parameters. The proposed analytical profiles of entrainment and detrainment are
tested in GCM for long-term simulation and are evaluated in the light of the results from the original Tiedtke's scheme and
another mass flux scheme due to Emanuel. The variations of Indian monsoon rainfall have been examined with these schemes in
a general circulation model. Evaluation of the simulated rainfall against observations is done by empirical orthogonal function
(EOF) analysis for the Indian Monsoon region. It is noted that the spatial and temporal variations of the all-India monsoon
rainfall are sensitive to the formulation of entrainment and detrainment in a mass flux scheme, and that the new formulation
can effectively represent the increased dilution with height in deep clouds. 相似文献
9.
During the field cruises of the Indian Ocean Experiment (INDOEX) extensive measurements on the atmospheric chemical and aerosol composition are undertaken to study the long-range transport of air pollution from south and southeast Asia towards the Indian Ocean during the dry monsoon season in 1998 and 1999. The present paper discusses the temporal and spatial variations in aerosols and aerosol forcing during the winter monsoon season (January-March) for INDOEX first field phase (FFP) in 1998 and INDOEX intensive field phase (IFP) in 1999. An interactive chemistry/aerosol model (LMDZ.3.3) is used to investigate the variation in the spatial distribution of tropospheric sulphate aerosols during 1998 and 1999. The model results depict major enhancement in the sulphate aerosol concentrations, radiative forcing (RF) and optical depth over the Indian subcontinent and adjoining marine areas between INDOEX-FFP and IFP. A significant increase in transport of sulphate aerosols from the continents to the Indian Ocean region has also been simulated during the winter monsoon in 1999. The mean RF over INDOEX-FFP in 1998 is found to be ?1.2 Wm–2 while it increased to ?1.85 Wm–2 during INDOEX-IFP in 1999. Model results reveal a mean sulphate aerosol optical depth (AOD) of 0.08 and 0.14 over Indian subcontinent during 1998 and 1999, respectively. The model results suggest that elevated AOD downwind of source regions in India can significantly affect the regional air quality and adjoining marine environments. 相似文献
10.
Naveen Kumar Martyn Tranter Parmanand Sharma Manish Pandey Prabhat Ranjan 《水文科学杂志》2019,64(2):179-189
Long-term data (2003–2015) on meltwater chemistry, mass balance and discharge of a benchmark glacier (Chhota Shigri Glacier, India) were studied to determine any association between these variables. To infer the factors governing the alteration of chemical weathering processes in glacierized basins, multi-annual records of the hydrochemical indices (Ca2++Mg2+/Na++K+) and the C-ratio were also examined. A succession of negative mass balance years has resulted in a decline in solute concentrations in the runoff, as discharge has increased. The (Ca2++Mg2+/Na++K+) and C-ratio are highest during periods of negative annual mass balance, when the spatial extent of the channelized drainage system increases. Conversely, these ratios are lowest in positive mass balance years, when the spatial extent of the channelized drainage system decreases, and chemical weathering in the distributed drainage system becomes more dominant. This paper is the first to show the inter-annual linkages between meltwater chemistry, mass balance and discharge for a valley glacier. 相似文献