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121.
The Global Warming Debate: A Review of the State of Science 总被引:2,自引:0,他引:2
A review of the present status of the global warming science is presented in this paper. The term global warming is now popularly used to refer to the recent reported increase in the mean surface temperature of the earth; this increase being attributed to increasing human activity and in particular to the increased concentration of greenhouse gases (carbon dioxide, methane and nitrous oxide) in the atmosphere. Since the mid to late 1980s there has been an intense and often emotional debate on this topic. The various climate change reports (1996, 2001) prepared by the IPCC (Intergovernmental Panel on Climate Change), have provided the scientific framework that ultimately led to the Kyoto protocol on the reduction of greenhouse gas emissions (particularly carbon dioxide) due to the burning of fossil fuels. Numerous peer-reviewed studies reported in recent literature have attempted to verify several of the projections on climate change that have been detailed by the IPCC reports.The global warming debate as presented by the media usually focuses on the increasing mean temperature of the earth, associated extreme weather events and future climate projections of increasing frequency of extreme weather events worldwide. In reality, the climate change issue is considerably more complex than an increase in the earth’s mean temperature and in extreme weather events. Several recent studies have questioned many of the projections of climate change made by the IPCC reports and at present there is an emerging dissenting view of the global warming science which is at odds with the IPCC view of the cause and consequence of global warming. Our review suggests that the dissenting view offered by the skeptics or opponents of global warming appears substantially more credible than the supporting view put forth by the proponents of global warming. Further, the projections of future climate change over the next fifty to one hundred years is based on insufficiently verified climate models and are therefore not considered reliable at this point in time. 相似文献
122.
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124.
Savita B. Morwal S. G. Nagar V. S. N. Murty P. Seetaramayya 《Journal of Earth System Science》2006,115(5):587-599
During the period 12–16 June 1996 a tropical cyclonic storm formed over the southwest Bay of Bengal and moved in a north-northeasterly
direction. The thermodynamic characteristics of this system are investigated by utilizing the surface and upper air observations
collected onboardORV Sagar Kanya over the Bay of Bengal region. The response of the cyclonic storm is clearly evident from the ship observations when the
ship was within the distance of 600–800 km from the cyclonic storm. This study explores why (i) the whole atmosphere from
surface to 500 hPa had become warm and moist during the cyclonic storm period as compared to before and after the formation
of this system and (ii) the lower layer of the atmosphere had become stable during the formative stage of the cyclonic storm. 相似文献
125.
V. Ramesh Babu V. S. N. Murty L. V. G. Rao C. V. Prabhu V. Tilvi 《Journal of Earth System Science》2000,109(2):255-265
Hydrographic data collected on board ORV Sagar Kanya in the southern Bay of Bengal during the BOBMEX-Pilot programme (October–November
1998) have been used to describe the thermohaline structure and circulation in the upper 200 m water column of the study region.
The presence of seasonal Inter-Tropical Convergence Zone (ITCZ) over the study area, typically characterized with enhanced
cloudiness and flanked by the respective east/northeast winds on its northern part and west/southwest winds on its southern
part, has led to net surface heat loss of about 55 W/m2. The sea surface dynamic topography relative to 500 db shows that the upper layer circulation is characterised by a cyclonic
gyre encompassing the study area. The eastward flowing Indian Monsoon Current (IMC) between 5‡N and 7‡N in the south and its
northward branching along 87‡E up to 13‡N appear to feed the cyclonic gyre. The Vessel-Mounted Acoustic Doppler Current Profiler
(VM-ADCP) measured currents confirm the presence of the cyclonic gyre in the southern Bay of Bengal during the withdrawing
phase of the southwest monsoon from the northern/central parts of the Bay of Bengal. 相似文献
126.
The storm surge phenomenon in the Arabian Gulf, including the Strait of Hormuz, is discussed with particular emphasis on the development of mathematical models for prediction purposes. The Gulf is mainly influenced by extra-tropical weather systems, whereas the region south of the Strait of Hormuz is affected by tropical cyclones. The west-to-east directed extra-tropical cyclone tracks and the generally east-to-west directed tropical cyclone tracks converge near the Strait of Hormuz. A meso-scale weather system that deserves special attention in prescribing the meteorological forcing functions is the so-called winter Shamal. A two-dimensional numerical model is developed to study the storm surges in the Arabian Gulf. The results show that the Gulf is subject to major negative and positive storm surges. Strong winds associated with the Shamal system, coupled with atmospheric pressure gradients, topography and tidal effects, can give rise to water level deviations of several meters. Storm surges observed during the period 17–19 January 1973 show that negative values in the 0.5 to 1.0m range were widespread in the Gulf. 相似文献
127.
Lina P. Mergulhao Rahul Mohan V. S. N. Murty M. V. S. Guptha D. K. Sinha 《Journal of Earth System Science》2006,115(4):415-428
Sediment trap samples collected from a depth of 1018 m in the Central Arabian Sea Trap (CAST) at 14°28.2′N, 64°35.8′E were
analyzed for temporal variation of coccolithophore fluxes from October 1993 to August 1994. Out of the twenty species of coccolithophores
encountered,Gephyrocapsa oceanica, Emiliania huxleyi, Umbilicosphaera sibogae andUmbellosphaera irregularis were the most abundant. The total coccolithophore fluxes ranged from 28.5 × 106m-2d-1 to 50.3 × 106m-2d-1 showing seasonality with higher fluxes during the northeast (NE) monsoon and lower fluxes during the spring intermonsoon.
The higher fluxes were attributed to the enhancement of primary production in the central Arabian Sea due to southward extent
of nutrients from the northeast Arabian Sea by the prevailing surface currents. Similarly, the occurrences of relatively lower
coccolithophore fluxes during the spring intermonsoon and southwest (SW) monsoon were attributed to the low nutrients in the
warm, shallow surface mixed layer and downwelling to the south of Findlater Jet respectively in the central Arabian Sea. Some
of the coccolithophore species such asE. huxleyi, G. oceanica, Calcidiscus leptoporus andUmbellosphaera tenuis showed signs of dissolution. 相似文献
128.
Although the frequency of tropical cyclones is less in the Arabian sea compared to that of the Bay of Bengal, there are several severe tropical cyclones which caused extensive damage along the Gujarat coast. In view of the high tidal range in the funnel-shaped gulfs of the Khambhat and the Kachch, it is very useful to study the surge response in these regions. There is always a possibility of abnormal rise of sea level when the occurrence of surge coincides with high tide, which may eventually cause inundation of vast stretches of shallow coastal areas. In view of this, a location specific fine resolution model is developed for the Gujarat coast. The east-west and north-south grid distances for the model are 5.1 km and 5.2 km, respectively. Several numerical experiments are carried out to compute the extreme sea levels using the wind stress forcings representative of 1982, 1996, and 1998 cyclones, which crossed this region. The model-computed extreme sea levels are in good agreement with the available observations. 相似文献
129.
The surface layers of the Bay of Bengal along the east coast of India exhibit intricate stratification owing to the differential
distribution of freshwaters. The winter (January–February) cooling of the salinity-induced stable layers results in the development
of thermal inversions that deteriorate toward the end of the season. The study focuses on the behavior of the thermal inversions
in the light of the variable stratification and the monsoon imposed reversing coastal current. To address the associated processes,
a three-dimensional Princeton Ocean Model is applied for the east coast of India, and numerical experiments carried out to
study the means by which the thermal inversions tend to perish with the passage of winter. The model domain with variable
curvilinear grid uses input fields that comprise realistic bathymetry and initial temperature/salinity conforming to winter/specified
stratification. The surface forcing comprises wind stress and diurnal pattern air–sea heat fluxes. The body forcing is derived
from the periodic tidal elevations at the open boundaries. It has been found that the thermal inversions tend to sustain as
the equator-ward flowing East India Coastal Current (EICC) traps the cool low saline waters between Paradip and Kakinada.
The current off Paradip is weak and variable and is not a part of EICC. Consequently, in the absence of replenishment of cool
and freshsurface waters, the temperature/salinity gradients get eroded steadily. No thermal inversions are noticed south of
Kakinada because of relatively weak current with diminished vertical salinity gradient. As the nature of stratification encountered
in the bay is highly variable due to diverse reasons, the behavior of internal waves under different stratification scenarios
is also addressed. Numerical experiments indicate that the energy/amplitude of the internal waves are comparable in the surface
layers for any stratification, where as it is certain orders exalted in the deeper waters of the strong stratification scenario.
Further, it is found that the energies and pattern of the temperature oscillations conform to the nature of mixed tide at
the corresponding latitude. The underneath stratification is found to be more responsible for the generation of internal waves compared to the local stratification. This implies that the body forcing emanating from below is the cardinal contributor for the generation of internal waves.
The numerical experiment with a flat and uniform bottom showing weak manifestation of internal waves endorses the same. This
connotes that the continental slopes are an effective generator of the internal waves and the energy flux conversion of the
barotropic tide to internal waves seems to be heavily dependent on the shoaling bottom. 相似文献
130.
Abstract The tsunami travel‐time charts that are presently in use by the Tsunami Warning Center were constructed originally in 1948 based on the hydrographic data available in the mid 1940s. Even the revised charts of 1971 made use of essentially the same data. It is shown here that the travel times deduced by these charts could be in error by as much as two hours in some cases. Even worse, the compiled travel times as deduced from these charts are generally greater than the observed travel times, which is a dangerous situation from a tsunami warning point of view. 相似文献