(3.237.232.196)
Users online: 13074     
Ijournet
Email id
 

TERI Information Digest on Energy and Environment
Year : 2002, Volume : 1, Issue : 1
First page : ( 154) Last page : ( 156)
Print ISSN : 0972-6721.

Climate change: Atmospheric chemistry and meteorology

 


[189]The effect of Indian Ocea n warming on the Indian monsoon: an atmosphere model study
Bachiochi D, Jha B, and Krishnamurti TN. 2001The results from an atmospheric modelling study using the Florida State University Global Special Model indicate that, in years such as 1997 when the Indian Ocean SSTs (sea surface temperatures) are high, the Indian monsoon exhibits a typical behaviour. During that year, an extended shift of the tropical convergence zone towards the north played a role in the regional Hadley cell anomalies. The local warm boundary conditions in the northwestern Indian Ocean aided the high rainfall anomaly in Western India during the model simulations. The upper level structure, exhibited in terms of the global velocity potential is slightly shifted to the east for 1997, but with the correct sign. This structure shows regions of convergence over Indonesia where severe drought had occurred. The performance of the model rainfall over the equatorial Indian Ocean was uncanny for most seasons studied. Overall, the model performed best over the oceanic regions.
(6 figures, 2 tables, 24 references)
Mausam52(1):151–162
Florida State University,
Department of Meteorology, Tallahassee FL32306–4520, USA

TopBack

[190]Quantifying uncertainties in climate system properties with the use of recent climate observations
Forest CE, Stone PH, Sokolov AP, Allen MR, et al. 2001The authors derive joint probability density distributions for three key uncertain properties of the climate system, using an optimal fingerprinting approach to compare simulations of an intermediate complexity climate model with three distinct diagnostics of recent climate observations. On the basis of the marginal probability distributions, the 5%-95% confidence intervals are 1.4-7.7 kelvin for climate sensitivity and — 0.30 to — 0.95 watt per square meter for the net aerosol forcing. The oceanic heat uptake is not well constrained, but ocean temperature observations do help to constrain climate sensitivity. The uncertainty in the net aerosol forcing is much smaller than the uncertainty range for the indirect aerosol forcing alone given in the IPCC's Third Assessment Report.
(4 figures, 20 references)
Science295(5552):113–117
Joint Program on the Science Policy of Global Change,
Massachusetts Institute of Technology, Cambridge, MA 02139, USA
<ceforest@mit.edu>

TopBack

[191]Global warming and monsoon climate
Lal M and Singh SK. 2001The response of the Asian summer monsoon to transient increase of GHGs and sulfate aerosols in the Earth's atmosphere is examined using the data generated in numerical experiments with available coupled A-OGCMs. A comparison of observed and model-simulated trends in monthly mean near-surface temperature and rainfall over the region provides evidence of skill of the A-OGCMs in simulating the regional climatology. The potential role of the sulfate aerosols in obscuring the GHG-in-duced warming over the Indian subcontinent is discussed. Even though the simulated total seasonal rainfall over the Indian subcontinent during summer monsoon season is underestimated in most of the A-OGCMs, the year to year variability in simulated monsoon rainfall over the study region is found to be in fair agreement with the observed climatology.
(11 figures, 2 tables, 11 references)
Mausam52(1):245–262
Centre for Atmospheric Sciences,
Indian Institute of Technology, Hauz Khas, New Delhi-110 016, India

TopBack

[192]Regional climate changes due to double CO2 simulation by CCM3
Pal PK, Thapliyal PK, and Dwavedi AK. 2001Sensitivity experiments with global climate models indicate that CO2 plays an important role in global climate changes. An equilibrium experiment has been conducted with CCM3 (Community Climate Model) in which the amount of CO2 in the model atmosphere is doubled and the differences in resulting climate has been examined. The results show that there is an overall decrease in outgoing long-wave radiation indicating the possible increase in cloudiness. The total rainfall may not change significantly but the temporal and spatial distributions over India are likely to change as observed in past long-term trends.
(11 figures, 7 references)
Mausam52(1):221–228
Atmospheric Sciences Division,
Space Applications Centre, Ahmedabad - 380 053, India

TopBack

[193]Quantifying the risk of extreme seasonal precipitation events in a changing climate
Palmer TN and Raisanen J. 2001Increasing concentrations of atmospheric carbon dioxide will almost certainly lead to changes in global mean climate. However, as extreme events are (by definition) rare, it is significantly more difficult to quantify the risk of extremes. Ensemble-based probabilistic predictions, as used in short- and medium-term forecasts of weather and climate, are more useful than deterministic forecasts using a 'best guess' scenario to address this sort of problem. The authors present a probabilistic analysis of 19 global climate model simulations with a generic binary decision model. They also estimate that the probability of total boreal winter precipitation exceeding two standard deviations above normal will increase by a factor of five, over parts of the UK, over the next 100 years. Furthermore, they find similar increases in probability for the Asian monsoon region in boreal summer, with implications for flooding in Bangladesh. Further practical applications of these techniques would be helped by the use of larger ensembles (for a more complete sampling of model uncertainty) and a wider range of scenarios at a resolution adequate to analyse average-size river basins.
(3 figures, 10 references)
Nature415(6871):512–514
European Centre for Medium-Range Weather Forecasts,
Shinfield Park, Reading, Berks RG2 9AX, UK

TopBack

[194]Searching for a fingerprint of global warming in the Asian summer monsoon
Stephenson DB, Douville H, and Kumar KR. 2001This study investigates possible trends in several large-scale indices that describe the Asian summer monsoon. Results from recent atmospheric general circulation experiments are used to provide clues as to how the monsoon might be changing due to the effects of global warming. Interestingly, this study has found that the large-scale wind shear monsoon indices have been decreasing at a rate of 0.1%-0.3% per year (based on NECP/ NCAR) reanalyses 1958-98) in quantitative agreement with recent results from doubled CO2 simulations made using several state-of-the-art climate models. Nevertheless, despite the weakening of the monsoon circulation, all-India rainfall shows no clear trend in either the model results or in the observation reanalyses from 1958-98. Multiple regression is used to separate out the dynamical residual. A simple dimensionless Multivariate Monsoon Index is proposed that could be of use in monitoring global warming changes in the monsoon.
(2 figures, 2 tables, 31 references)
Mausam52(1):213–220
Department of Meteorology,
University of Reading, Earley Gate, PO Box 243, Reading RG6 6BB, UK

TopBack

 
║ Site map ║ Privacy Policy ║ Copyright ║ Terms & Conditions ║ Page Rank Tool
733,451,087 visitor(s) since 30th May, 2005.
All rights reserved. Site designed and maintained by DIVA ENTERPRISES PVT. LTD..
Note: Please use Internet Explorer (6.0 or above). Some functionalities may not work in other browsers.