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1.
A transient climate change simulation with greenhouse gas and aerosol forcing: projected climate to the twenty-first century 总被引:3,自引:0,他引:3
The potential climatic consequences of increasing atmospheric greenhouse gas (GHG) concentration and sulfate aerosol loading
are investigated for the years 1900 to 2100 based on five simulations with the CCCma coupled climate model. The five simulations
comprise a control experiment without change in GHG or aerosol amount, three independent simulations with increasing GHG and
aerosol forcing, and a simulation with increasing GHG forcing only. Climate warming accelerates from the present with global
mean temperatures simulated to increase by 1.7 °C to the year 2050 and by a further 2.7 °C by the year 2100. The warming is
non-uniform as to hemisphere, season, and underlying surface. Changes in interannual variability of temperature show considerable
structure and seasonal dependence. The effect of the comparatively localized negative radiative forcing associated with the
aerosol is to retard and reduce the warming by about 0.9 °C at 2050 and 1.2 °C at 2100. Its primary effect on temperature
is to counteract the global pattern of GHG-induced warming and only secondarily to affect local temperatures suggesting that
the first order transient climate response of the system is determined by feedback processes and only secondarily by the local
pattern of radiative forcing. The warming is accompanied by a more active hydrological cycle with increases in precipitation
and evaporation rates that are delayed by comparison with temperature increases. There is an “El Nino-like” shift in precipitation
and an overall increase in the interannual variability of precipitation. The effect of the aerosol forcing is again primarily
to delay and counteract the GHG-induced increase. Decreases in soil moisture are common but regionally dependent and interannual
variability changes show considerable structure. Snow cover and sea-ice retreat. A PNA-like anomaly in mean sea-level pressure
with an enhanced Aleutian low in northern winter is associated with the tropical shift in precipitation regime. The interannual
variability of mean sea-level pressure generally decreases with largest decreases in the tropical Indian ocean region. Changes
to the ocean thermal structure are associated with a spin-down of the Atlantic thermohaline circulation together with a decrease
in its variability. The effect of aerosol forcing, although modest, differs from that for most other quantities in that it
does not act primarily to counteract the GHG forcing effect. The barotropic stream function in the ocean exhibits modest change
in the north Pacific but accelerating changes in much of the Southern Ocean and particularly in the north Atlantic where the
gyre spins down in conjunction with the decrease in the thermohaline circulation. The results differ in non-trivial ways from
earlier equilibrium 2 × CO2 results with the CCCma model as a consequence of the coupling to a fully three-dimensional ocean model and the evolving nature
of the forcing.
Received: 24 September 1998 / Accepted: 8 October 1999 相似文献
2.
F. Mkankam Kamga 《Theoretical and Applied Climatology》2000,67(1-2):97-107
Summary Four coupled atmosphere-ocean general circulation models were examined for the ability of their control runs to simulate
present climate given present forcings. The area of study is mainly Cameroon and some of its surrounding areas (0–25° E, 5° S-30° N).
These models are from the UK Meteorological Office Hadley Centre (HadCM2), the German Max-Planck-Institut für Meteorologie
(ECHAM4), the Canadian Centre for Climate Modelling and Analysis (CGCM1) and the Australian Commonwealth Science and Industrial
Research Organisation (CSIRO-Mk2). The ability of the models to reproduce the observed spatial and temporal patterns was studied.
ECHAM4 and HadCM2 were found to reproduce the spatial pattern well, with a correlation of more than 90%. They also simulated
the main annual features of both temperature and rainfall. The CSIRO-Mk2 model was slightly less successful and the CGCM1
had the worst results for the area, especially as concern rainfall. In view of these results, ECHAM4 and HADCM2 were used
to evaluate projected changes in rainfall and temperature resulting from increased concentration of greenhouse gases in the
atmosphere for the 30 year period 2040 to 2070.
Received February 15, 1999/Revised March 10, 2000 相似文献
3.
L. D. D. Harvey 《Climate Dynamics》2000,16(7):491-500
This work uses an energy balance climate model (EBCM) with explicit infrared radiative transfer, parametrized tropospheric
temperature and humidity profiles, and separate stratosphere, troposphere, and surface energy balances, to investigate claims
that a downward redistribution of tropospheric water vapor in response to surface warming could serve as a strong negative
feedback on climatic change. A series of sensitivity tests is carried out using: (1) a variety of relationships between total
precipitable water in the troposphere and temperature; (2) feedbacks between surface temperature and the vertical distribution
of tropospheric water vapor at low latitudes; and (3) feedback between surface temperature or meridional temperature gradient
and lapse rate. Fixed relative humidity (RH) enhances the global mean surface temperature response to a CO2 doubling by only 50% compared to fixed absolute humidity, giving a response of 1.8 K. When water vapor is assumed to be redistributed
downward between 30°S–30°N such that a 1 K surface warming reduces total precipitable water above 600 hPa by 10%, the global
mean surface air temperature response is reduced to 1.2 K. Assuming a stronger downward redistribution in relation to surface
temperature change has a rapidly diminishing marginal effect on global mean and tropical surface temperature response, while
slightly increasing the warming at high latitudes due to the parametrized dependence of middle-to-high latitude lapse rate
on the meridional temperature gradient. A modest downward water vapor redistribution, such that absolute humidity in the upper
troposphere at subtropical latitudes is constant as total precipitable water increases, can reduce the tropical temperature
sensitivity to less than 1 K, while increasing the equator-to-pole amplification of the surface air temperature response from
a factor of about three to a factor of four. However, it is concluded that whatever changes in future GCM response might occur
as a result of new parametrizations of subgrid-scale processes, they are exceedingly unlikely to produce a climate sensitivity
to a CO2 doubling of less than 1 K even if there is a strong downward shift in the water vapor distribution as climate warms.
Received: 23 February 1998 / Accepted: 1 November 1999 相似文献
4.
Summary The possibility of climate change in the Korean Peninsula has been examined in view of the general increase in greenhouse
gases. Analyses include changes in annual temperature and precipitation. These analyses are supplemented with our observations
regarding the apparent decrease of forest areas.
It was found that there was a 0.96 °C (0.42 °C per decade) increase in annual mean temperature between 1974 and 1997. The
increase in large cities was 1.5 °C but only 0.58 °C at rural and marine stations. The difference in the mean temperature
between large cities and rural stations was small from 1974 to 1981. However, the difference increased from 1982 to 1997.
In particular, the warming appears most significant in winter. Prior to 1982, the lowest temperatures were often −18 °C in
central Korea, and since then the lowest temperatures have been only −12∼−14 °C. Recently, the minimum January temperature
has increased at a rate of 1.5 °C per decade. It is estimated that the increase of1 °C in annual mean temperature corresponds
to about a 250 km northward shift of the subtropical zone boundary.
The analysis of data from 1906 to 1997 indicates a trend of increasing annual precipitation, an increase of 182 mm during
the 92-year peirod, with large year-to-year variations. More than half of the annual mean amount, 1,274 mm, occurred from
June to September.
Meteorological data and satellite observations suggest that changes have occurred in the characteristics of the quasi-stationary
fronts that produce summer rain. In recent years scattered local heavy showers usually occur with an inactive showery front,
in comparison with the classical steady rain for more than three weeks. For instance, local heavy rainfall, on 6 August 1998
was in the range of 123–481 mm. The scattered convective storms resulted in flooding with a heavy toll of approx. 500 people.
The northward shift of the inactive showery front over Korea, and of a convergence zone in central China, correlate with the
increase in temperature. It has been suggested that the decrease in forest areas and the change in ground cover also contribute
to the warming of the Korean Peninsula.
Received March 16, 2000 相似文献
5.
Observed and projected climate change in Taiwan 总被引:1,自引:0,他引:1
Summary
This study examined the secular climate change characteristics in Taiwan over the past 100 years and the relationship with
the global climate change. Estimates for the likelihood of future climate changes in Taiwan were made based on the projection
from the IPCC climate models.
In the past 100 years, Taiwan experienced an island-wide warming trend (1.0–1.4 °C/100 years). Both the annual and daily temperature
ranges have also increased. The warming in Taiwan is closely connected to a large-scale circulation and SAT fluctuations,
such as the “cool ocean warm land” phenomenon. The water vapor pressure has increased significantly and could have resulted
in a larger temperature increase in summer. The probability for the occurrence of high temperatures has increased and the
result suggests that both the mean and variance in the SAT in Taiwan have changed significantly since the beginning of the
20th century. Although, as a whole, the precipitation in Taiwan has shown a tendency to increase in northern Taiwan and to
decrease in southern Taiwan in the past 100 years, it exhibits a more complicated spatial pattern. The changes occur mainly
in either the dry or rainy season and result in an enhanced seasonal cycle. The changes in temperature and precipitation are
consistent with the weakening of the East Asian monsoon.
Under consideration of both the warming effect from greenhouse gases and the cooling effect from aerosols, all projections
from climate models indicated a warmer climate near Taiwan in the future. The projected increase in the area-mean temperature
near Taiwan ranged from 0.9–2.7 °C relative to the 1961–1990 averaged temperature, when the CO2 concentration increased to 1.9 times the 1961–1990 level. These simulated temperature increases were statistically significant
and can be attributed to the radiative forcing associated with the increased concentration of greenhouse gases and aerosols.
The projected changes in precipitation were within the range of natural variability for all five models. There is no evidence
supporting the possibility of precipitation changes near Taiwan based on the simulations from five IPCC climate models.
Received February 5, 2001 Revised July 30, 2001 相似文献
6.
Stream temperature sensitivity to climate warming in California’s Sierra Nevada: impacts to coldwater habitat 总被引:2,自引:0,他引:2
Sarah E. Null Joshua H. Viers Michael L. Deas Stacy K. Tanaka Jeffrey F. Mount 《Climatic change》2013,116(1):149-170
Water temperature influences the distribution, abundance, and health of aquatic organisms in stream ecosystems, so understanding the impacts of climate warming on stream temperature will help guide management and restoration. This study assesses climate warming impacts on stream temperatures in California’s west-slope Sierra Nevada watersheds, and explores stream temperature modeling at the mesoscale. We used natural flow hydrology to isolate climate induced changes from those of water operations and land use changes. A 21 year time series of weekly streamflow estimates from WEAP21, a spatially explicit rainfall-runoff model were passed to RTEMP, an equilibrium temperature model, to estimate stream temperatures. Air temperature was uniformly increased by 2°C, 4°C, and 6°C as a sensitivity analysis to bracket the range of likely outcomes for stream temperatures. Other meteorological conditions, including precipitation, were unchanged from historical values. Raising air temperature affects precipitation partitioning into snowpack, runoff, and snowmelt in WEAP21, which change runoff volume and timing as well as stream temperatures. Overall, stream temperatures increased by an average of 1.6°C for each 2°C rise in air temperature, and increased most during spring and at middle elevations. Viable coldwater habitat shifted to higher elevations and will likely be reduced in California. Thermal heterogeneity existed within and between basins, with the high elevations of the southern Sierra Nevada and the Feather River watershed most resilient to climate warming. The regional equilibrium temperature modeling approach used here is well suited for climate change analysis because it incorporates mechanistic heat exchange, is not overly data or computationally intensive, and can highlight which watersheds are less vulnerable to climate warming. Understanding potential changes to stream temperatures from climate warming will affect how fish and wildlife are managed, and should be incorporated into modeling studies, restoration assessments, and licensing operations of hydropower facilities to best estimate future conditions and achieve desired outcomes. 相似文献
7.
The modification of greenhouse gas warming by the direct effect of sulphate aerosols 总被引:1,自引:0,他引:1
The Canadian Centre for Climate Modelling and Analysis (CCCma) second generation climate model (GCMII) consists of an atmospheric
GCM coupled to mixed layer ocean. It is used to investigate the climate response to a doubling of the CO2 concentration together with the direct effect of scattering by sulphate aerosols. As expected, the aerosols offset some of
the greenhouse gas (GHG) warming; the global annual mean screen temperature change due to doubled CO2 is 3.4 °C in this model and this is reduced to 2.7 °C when an estimate of the direct effect of anthropogenic sulphate aerosols
is included. The pattern of climate response to the comparatively localized aerosol forcing is not itself localized, and it
bears a striking resemblance to the response pattern that arises from the globally distributed change in GHG forcing. This
“non-local” response to “localized” forcing indicates that the pattern of climate response is determined, to first order,
by the overall magnitude of the change in forcing rather than its detailed nature or structure. Feedback processes operating
in the system apparently determine this pattern by locally amplifying and suppressing the response to the magnitude of the
change in forcing. The influence of the location of the change in forcing is relatively small. These “non-local” and “local”
effects of aerosol forcing are characterized and displayed and some of their consequences discussed. Effects on the moisture
budget and on the energetics of the global climate are also examined.
Received: 10 June 1997 / Accepted: 8 January 1998 相似文献
8.
The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments 总被引:47,自引:17,他引:30
C. Gordon C. Cooper C. A. Senior H. Banks J. M. Gregory T. C. Johns J. F. B. Mitchell R. A. Wood 《Climate Dynamics》2000,16(2-3):147-168
Results are presented from a new version of the Hadley Centre coupled model (HadCM3) that does not require flux adjustments
to prevent large climate drifts in the simulation. The model has both an improved atmosphere and ocean component. In particular,
the ocean has a 1.25° × 1.25° degree horizontal resolution and leads to a considerably improved simulation of ocean heat transports
compared to earlier versions with a coarser resolution ocean component. The model does not have any spin up procedure prior
to coupling and the simulation has been run for over 400 years starting from observed initial conditions. The sea surface
temperature (SST) and sea ice simulation are shown to be stable and realistic. The trend in global mean SST is less than 0.009 °C
per century. In part, the improved simulation is a consequence of a greater compatibility of the atmosphere and ocean model
heat budgets. The atmospheric model surface heat and momentum budget are evaluated by comparing with climatological ship-based
estimates. Similarly the ocean model simulation of poleward heat transports is compared with direct ship-based observations
for a number of sections across the globe. Despite the limitations of the observed datasets, it is shown that the coupled
model is able to reproduce many aspects of the observed heat budget.
Received: 1 October 1998 / Accepted: 20 July 1999 相似文献
9.
Haiyan Teng Warren M. Washington Gerald A. Meehl Lawrence E. Buja Gary W. Strand 《Climate Dynamics》2006,26(6):601-616
Arctic climate change in the Twenty-first century is simulated by the Community Climate System Model version 3.0 (CCSM3).
The simulations from three emission scenarios (A2, A1B and B1) are analyzed using eight (A1B and B1) or five (A2) ensemble
members. The model simulates a reasonable present-day climate and historical climate trend. The model projects a decline of
sea-ice extent in the range of 1.4–3.9% per decade and 4.8–22.2% per decade in winter and summer, respectively, corresponding
to the range of forcings that span the scenarios. At the end of the Twenty-first century, the winter and summer Arctic mean
surface air temperature increases in a range of 4–14°C (B1 and A2) and 0.7–5°C (B1 and A2) relative to the end of the Twentieth
century. The Arctic becomes ice-free during summer at the end of the Twenty-first century in the A2 scenario. Similar to the
observations, the Arctic Oscillation (AO) is the dominant factor in explaining the variability of the atmosphere and sea ice
in the 1870–1999 historical runs. The AO shifts to the positive phase in response to greenhouse gas forcings in the Twenty-first
century. But the simulated trends in both Arctic mean sea-level pressure and the AO index are smaller than what has been observed.
The Twenty-first century Arctic warming mainly results from the radiative forcing of greenhouse gases. The 1st empirical orthogonal
function (explains 72.2–51.7% of the total variance) of the wintertime surface air temperature during 1870–2099 is characterized
by a strong warming trend and a “polar amplification”-type of spatial pattern. The AO, which plays a secondary role, contributes
to less than 10% of the total variance in both surface temperature and sea-ice concentration. 相似文献
10.
The possible future impact of anthropogenic forcing upon the circulation of the Mediterranean, and the exchange through the
Strait of Gibraltar is investigated using a Cox-type model of the Mediterranean at 0.25° × 0.25° resolution, forced by “control”
and “greenhouse” scenarios provided by the HadCM2 coupled climate model. The current structure of the Mediterranean forced
by the “control” climate is compared with observations: certain aspects of the present circulation are reproduced, but others
are absent or incorrectly represented. Deficiencies are most probably due to weaknesses in the forcing climatology generated
by the climate model, so some caution must be exercised in interpreting the enhanced greenhouse simulation. Comparison of
the control and greenhouse scenarios suggests that deep-water production in the Mediterranean may be reduced or cease in the
relatively near future. The results also suggest that the Mediterranean outflow, may become warmer and more saline, but less
dense, and hence shallower. The volume of the exchange at the Strait of Gibraltar seems to be relatively insensitive to future
climate change, however. Our results indicate that a parameterisation of Gibraltar exchange and Mediterranean Outflow Water
(MOW) production may be able to provide adequate representation of the changes we observe for the purposes of the current
generation of climate models.
Received: 10 August 1998 / Accepted: 11 October 1999 相似文献
11.
Recent trends in observed temperature and precipitation extremes in the Yangtze River basin,China 总被引:14,自引:1,他引:14
Summary The present study is an analysis of the observed extreme temperature and precipitation trends over Yangtze from 1960 to 2002
on the basis of the daily data from 108 meteorological stations. The intention is to identify whether or not the frequency
or intensity of extreme events has increased with climate warming over Yangtze River basin in the last 40 years. Both the
Mann-Kendall (MK) trend test and simple linear regression were utilized to detect monotonic trends in annual and seasonal
extremes.
Trend tests reveal that the annual and seasonal mean maximum and minimum temperature trend is characterized by a positive
trend and that the strongest trend is found in the winter mean minimum in the Yangtze. However, the observed significant trend
on the upper Yangtze reaches is less than that found on the middle and lower Yangtze reaches and for the mean maximum is much
less than that of the mean minimum. From the basin-wide point of view, significant increasing trends are observed in 1-day
extreme temperature in summer and winter minimum, but there is no significant trend for 1-day maximum temperature. Moreover,
the number of cold days ≤0 °C and ≤10 °C shows significant decrease, while the number of hot days (daily value ≥35 °C) shows
only a minor decrease. The upward trends found in the winter minimum temperature in both the mean and the extreme value provide
evidence of the warming-up of winter and of the weakening of temperature extremes in the Yangtze in last few decades.
The monsoon climate implies that precipitation amount peaks in summer as does the occurrence of heavy rainfall events. While
the trend test has revealed a significant trend in summer rainfall, no statistically significant change was observed in heavy
rain intensity. The 1-day, 3-day and 7-day extremes show only a minor increase from a basin-wide point of view. However, a
significant positive trend was found for the number of rainstorm days (daily rainfall ≥50 mm). The increase of rainstorm frequency,
rather than intensity, on the middle and lower reaches contributes most to the positive trend in summer precipitation in the
Yangtze. 相似文献
12.
Last Glacial Maximum climate of the former Soviet Union and Mongolia reconstructed from pollen and plant macrofossil data 总被引:2,自引:2,他引:0
P. E. Tarasov O. Peyron J. Guiot S. Brewer V. S. Volkova L. G. Bezusko N. I. Dorofeyuk E. V. Kvavadze I. M. Osipova N. K. Panova 《Climate Dynamics》1999,15(3):227-240
An improved concept of the best analogues method was used to reconstruct the Last Glacial Maximum (LGM) climate from a set
of botanical records from the former Soviet Union and Mongolia. Terrestrial pollen and macrofossil taxa were grouped into
broad classes – plant functional types (PFTs), defined by the ecological and climatic parameters used in the BIOME1 model.
PFT scores were then calibrated in terms of modern climate using 1245 surface pollen spectra from Eurasia and North America.
In contrast to individual taxa, which exhibit great variability and may not be present in the palaeoassemblages, even in suitable
climates, PFTs are more characteristic of the vegetation types. The modified method thus allows climate reconstruction at
time intervals with partial direct analogues of modern vegetation (e.g. the LGM). At 18 kBP, mean temperatures were 20–29 °C
colder than today in winter and 5–11 °C colder in summer in European Russia and Ukraine. Sites from western Georgia show negative,
but moderate temperature anomalies compared to today: 8–11 °C in January and 5–7 °C in July. LGM winters were 7–15 °C colder
and summers were 1–7 °C colder in Siberia and Mongolia. Annual precipitation sums were 50–750 mm lower than today across northern
Eurasia, suggesting a weakening of the Atlantic and Pacific influences. Reconstructed drought index shows much drier LGM conditions
in northern and mid-latitude Russia, but similar to or slightly wetter than today around the Black Sea and in Mongolia, suggesting
compensation of precipitation losses by lower-than-present evaporation.
Received: 11 May 1998 / Accepted: 25 September 1998 相似文献
13.
Influence of vegetation changes during the Last Glacial Maximum using the BMRC atmospheric general circulation model 总被引:3,自引:0,他引:3
The influence of different vegetation distributions on the atmospheric circulation during the Last Glacial Maximum (LGM,
21 000 years before present) is investigated. The atmospheric general circulation model of the Bureau of Meteorology Research
Center was run using a modern vegetation and in a second experiment with a vegetation reconstruction for the LGM. It is found
that a change from conifer to desert and tundra causes an additional LGM cooling of 1–2 °C in Western Europe, up to −4 °C
in North America and −6 °C in Siberia. An expansion of dryland vegetation causes an additional annual cooling of 1–2 °C for
Australia and northern Africa. On the other hand, an increase of temperature (2 °C) is found in Alaska due to changes in circulation.
In the equatorial region the LGM vegetation leads to an increased modelled temperature of 0.5–1.5 °C and decreased precipitation
(30%) over land due to a reduction of the tropical rainforest, mainly in Indonesia, where the reduction of precipitation over
land is associated with an increase of precipitation of 30% over the western Pacific.
Received: 15 December 1999 / Accepted: 10 January 2001 相似文献
14.
Annual methane emission from Finnish mires estimated from eddy covariance campaign measurements 总被引:4,自引:0,他引:4
K. J. Hargreaves D. Fowler C. E. R. Pitcairn M. Aurela 《Theoretical and Applied Climatology》2001,70(1-4):203-213
Summary Measurements of landscape-scale methane emission were made over an aapa mire near Kaamanen in Finnish Lapland (69° 8′ N,
27° 16′ E, 155 m ASL). Emissions were measured during the spring thaw, in summer and in autumn. No effect of water table position
on CH4 emission was found as the water table remained at or above the surface of the peat. Methane emission fluxes increased with
surface temperature from which an activation energy of −99 kJ mol−1 was obtained. Annual emission from the site, modelled from temperature regression and short-term flux measurements made in
three separate years, was calculated to be 5.5 ± 0.4 g CH4 m−2 y−1 of which 0.6 ± 0.1 g CH4 m−2 y−1 (11%) was released during the spring thaw which lasted 20 to 30 days.
The effect of global warming on the CH4 budget of the site was estimated using the central scenario of the SILMU (Finnish Research Programme on Climate Change) model
which predicts annual mean temperature increases of 1.2, 2.4 and 4.4 °C in 2020, 2050 and 2100, respectively. Maximum enhancements
in CH4 emission due to warming were calculated to be 18, 40 and 84% for 2020, 2050 and 2100, respectively. Actual increases may
be smaller because prediction of changes in water table are highly uncertain.
Received September 17, 1999 Revised October 16, 2000 相似文献
15.
Summary Spatial-temporal characteristics of temperature variations were analyzed from China daily temperature based on 486 stations
during the period 1960–2000. The method of hierarchical cluster analysis was used to divide the territory into sub-regional
areas with a coherent evolution, both annually and seasonally. Areas numbering 7–9 are chosen to describe the regional features
of air temperature in mainland China.
All regions in mainland China experienced increasing trends of annual mean temperature. The trend of increasing temperature
was about 0.2–0.3 °C/10 yr in northern China and less than 0.1 °C/10 yr in southern China. In the winter season, the increasing
trend of temperature was about 0.5–0.7 °C/10 yr in northern China and about 0.2–0.3 °C/10 yr in southern China. The increasing
trend of autumn temperature was mainly located in northwestern China and southwestern China including the Tibetan Plateau.
In spring, the rising trend of temperature was concentrated in Northeast China and North China while there was a declining
temperature trend of −0.13 °C/10 yr in the upper Yangtze River. In summer, the declining trend of temperature was only concentrated
in the mid-low valley of the Yangtze and Yellow Rivers while surrounding this valley there were increasing trends in South
China, Southwest China, Northwest China, and Northeast China.
Rapid changes in temperature in various regions were detected by the multiple timescale t-test method. The year 1969 was a rapid change point from a high temperature to a low temperature along the Yangtze River
and South China. In the years 1977–1979, temperature significantly increased from a lower level to a higher level in many
places except for regions in North China and the Yangtze River. Another rapid increasing temperature trend was observed in
1987. In the years 1976–1979, a positive rapid change of summer temperature occurred in northwestern China and southwestern
China while a decreasing temperature was found between the Yellow River and the Yangtze River. A rapid increase of winter
temperature was found for 1977–1979 and 1985–1986 in many places.
There were increasing events of extreme temperature in broad areas except in the north part of Northeast China and the north
part of the Xinjiang region. In winter, increasing temperature of the climate state and weakening temperature extremes are
observed in northern China. In summer, both increasing temperature of the climate state and enhancing temperature extremes
were commonly exhibited in northern China.
Present address: Linfen Meteorological Office, Linfen 041000, Shanxi Province, China. 相似文献
16.
Summary Near surface climate was observed through temperature profiling from the surface to 2.47 m height in an urban vegetated park
and its surroundings in central Stockholm, Sweden. Measurements were conducted during three summer days by mobile traverses.
Air temperature differences between the built-up area and the park were in the range of 0.5–0.8 °C during the day and reached
a maximum of 2 °C at sunset. The thermal stratification of the air was mainly stable in the park and unstable in the built-up
area. Inverse air temperature profiles in the park were less stable in open than in shady areas, and close to neutral at midday.
The most unstable air was found in the north–south orientated canyons in the early afternoon. Possible heat advection from
the surroundings, and thus uncoupling between the surface and the air, was identified through temperature gradients pointing
at different directions within the 2.47 m profile. Examples at midday indicated that warm air advected as far as 150 m into
the park. 相似文献
17.
Modelling the response of glaciers to climate change by applying volume-area scaling in combination with a high resolution GCM 总被引:4,自引:0,他引:4
A seasonally and regionally differentiated glacier model is used to estimate the contribution that glaciers are likely to
make to global sea level rise over a period of 70 years. A high resolution general circulation model (ECHAM4 T106) is used
to estimate temperature and precipitation changes for a doubled CO2 climate and serves as input for the glacier model. Volume-area relations are used to take into account the reduction of glacier
area resulting from greenhouse warming. Each glacieriated region has a specified glacier size distribution, defined by the
number of glaciers in a size class and a mean area. Changes in glacier volume are calculated by a precipitation dependent
mass balance sensitivity. The model predicts a global sea level rise of 57 mm over a period of 70 years. This corresponds
to a sensitivity of 0.86 mm yr−1K−1. Assuming a constant glacier area as done in earlier work leads to an overestimation of 19% for the contribution to sea level
rise.
Received: 16 August 2000 / Accepted: 21 May 2001 相似文献
18.
Variations in the Temperature Regime Across the Mediterranean During the Last Century and their Relationship with Circulation Indices 总被引:2,自引:2,他引:0
Summary Circulation types were identified by means of zonal and meridional indices calculated separately over ten different regions
of 20°×20° over the Mediterranean and Europe. Seasonal temperature trends in 22 grid boxes of 5°×5° covering the entire Mediterranean,
and at six stations Lisbon, Madrid, Florence, Luqa (Malta), Athens and Jerusalem, were calculated.
A warming trend in the period 1873–1989 was detected. The warming is more evident in the western Mediterranean with an average
rate of about 0.4 [°C/100 yr], than in the eastern Mediterranean with an increase of only 0.2 [°C/100 yr]. A cooling trend
in autumn in the eastern Mediterranean with an average rate of −0.5 [°C/100 yr] was detected and attributed to an increase
in northerly meridional circulation in that region.
Warming trends at Lisbon, Madrid, Florence, Athens and Jerusalem, were more important than the trends in the grid boxes containing
these stations. This rapid warming was attributed to urban effects. No such effects were found in Luqa due to its location
and the lack of urban effects there.
Temperatures at Luqa, Athens and Jerusalem are highly positively correlated. Likewise, temperatures at Lisbon and Madrid.
Temperatures at Florence are either correlated with Madrid or with Luqa. Negative or no correlations were found between Lisbon
or Madrid with Athens or Jerusalem, except during the winter. This was attributed to the fact that favourable circulation
for high temperatures in the eastern stations was opposite to the favourable circulation for high temperatures in the western
stations and vice versa.
Finally, the above reinforces the concept of a Mediterranean Oscillation between the western and eastern basins.
Received November 14, 1997 Revised June 2, 1998 相似文献
19.
Alpine ecosystems in permafrost region are extremely sensitive to climate change. The headwater regions of Yangtze River and
Yellow River of the Qinghai-Tibet plateau permafrost area were selected. Spatial-temporal shifts in the extent and distribution
of tundra ecosystems were investigated for the period 1967–2000 by landscape ecological method and aerial photographs for
1967, and satellite remote sensing data (the Landsat’s TM) for 1986 and 2000. The relationships were analyzed between climate
change and the distribution area variation of tundra ecosystems and between the permafrost change and tundra ecosystems. The
responding model of tundra ecosystem to the combined effects of climate and permafrost changes was established by using statistic
regression method, and the contribution of climate changes and permafrost variation to the degradation of tundra ecosystems
was estimated. The regional climate exhibited a tendency towards significant warming and desiccation with the air temperature
increased by 0.4–0.67°C/10a and relative stable precipitation over the last 45 years. Owing to the climate continuous warming,
the intensity of surface heat source (HI) increased at the average of 0.45 W/m2 per year, the difference of surface soil temperature and air temperature (DT) increased at the range of 4.1°C–4.5°C, and
the 20-cm depth soil temperature within the active layer increased at the range of 1.1°C–1.4°C. The alpine meadow and alpine
swamp meadow were more sensitive to permafrost changes than alpine steppe. The area of alpine swamp meadow decreased by 13.6–28.9%,
while the alpine meadow area decreased by 13.5–21.3% from 1967 to 2000. The contributions of climate change to the degradation
of the alpine meadow and alpine swamp was 58–68% and 59–65% between 1967 and 2000. The synergic effects of climate change
and permafrost variation were the major drivers for the observed degradation in tundra ecosystems of the Qinghai-Tibet plateau. 相似文献
20.
The Urban Heat Island Effect at Fairbanks, Alaska 总被引:13,自引:0,他引:13
Summary Using climatic data from Fairbanks and rurally situated Eielson Air Force Base in Interior Alaska, the growth of the Fairbanks
heat island was studied for the time period 1949 – 1997. The climate records were examined to distinguish between a general
warming trend and the changes due to an increasing heat island effect. Over the 49-year period, the population of Fairbanks
grew by more than 500%, while the population of Eielson remained relatively constant. The mean annual heat island observed
at the Fairbanks International Airport grew by 0.4 °C, with the winter months experiencing a more significant increase of
1.0 °C. Primary focus was directed toward long-term heat island characterization based on season, wind speed, cloud cover,
and time of day. In all cases, the minima temperatures were affected more than maxima and periods of calm or low wind speeds,
clear winter sky conditions, and nighttime exhibited the largest heat island effects.
Received August 17, 1998 Revised March 26, 1999 相似文献