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1.
Daily and sub-daily weather data are often required for hydrological and environmental modeling. Various weather generator programs have been used to generate synthetic climate data where observed climate data are limited. In this study, a weather data generator, ClimGen, was evaluated for generating information on daily precipitation, temperature, and wind speed at four tropical watersheds located in Hawai??i, USA. We also evaluated different daily to sub-daily weather data disaggregation methods for precipitation, air temperature, dew point temperature, and wind speed at M??kaha watershed. The hydrologic significance values of the different disaggregation methods were evaluated using Distributed Hydrology Soil Vegetation Model. MuDRain and diurnal method performed well over uniform distribution in disaggregating daily precipitation. However, the diurnal method is more consistent if accurate estimates of hourly precipitation intensities are desired. All of the air temperature disaggregation methods performed reasonably well, but goodness-of-fit statistics were slightly better for sine curve model with 2?h lag. Cosine model performed better than random model in disaggregating daily wind speed. The largest differences in annual water balance were related to wind speed followed by precipitation and dew point temperature. Simulated hourly streamflow, evapotranspiration, and groundwater recharge were less sensitive to the method of disaggregating daily air temperature. ClimGen performed well in generating the minimum and maximum temperature and wind speed. However, for precipitation, it clearly underestimated the number of extreme rainfall events with an intensity of >100 mm/day in all four locations. ClimGen was unable to replicate the distribution of observed precipitation at three locations (Honolulu, Kahului, and Hilo). ClimGen was able to reproduce the distributions of observed minimum temperature at Kahului and wind speed at Kahului and Hilo. Although the weather data generation and disaggregation methods were concentrated in a few Hawaiian watersheds, the results presented can be used to similar mountainous location settings, as well as any specific locations aimed at furthering the site-specific performance evaluation of these tested models. 相似文献
2.
Modelling climate change impacts on maize growth and development in the Czech Republic 总被引:5,自引:0,他引:5
Summary The crop growth model CERES-Maize is used to estimate the direct (through enhanced fertilisation effect of ambient CO2) and indirect (through changed climate conditions) effects of increased concentration of atmospheric CO2 on maize yields. The analysis is based on multi-year crop model simulations run with daily weather series obtained alternatively
by a direct modification of observed weather series and by a stochastic weather generator. The crop model is run in two settings:
stressed yields are simulated in water and nutrient limited conditions, potential yields in water and nutrient unlimited conditions.
The climate change scenario was constructed using the output from the ECHAM3/T42 model (temperature), regression relationships
between temperature and solar radiation, and an expert judgement (precipitation).
Results: (i) After omitting the two most extreme misfits, the standard error between the observed and modelled yields is 11%.
(ii) The direct effect of doubled CO2: The stressed yields would increase by 36–41% in the present climate and by 61–66% in the 2 × CO2 climate. The potential yields would increase only by 9–10% as the improved water use efficiency does not apply. (iii) The
indirect effect of doubled CO2: The stressed yields would decrease by 27–29% (14–16%) at present (doubled) ambient CO2 concentration. The increased temperature shortens the phenological phases and does not allow for the optimal development
of the crop. The simultaneous decrease of precipitation and increase of temperature and solar radiation deepen the water stress,
thereby reducing the yields. The reduction of the potential yields is significantly smaller as the effect of the increased
water stress does not apply. (iv) If both direct and indirect effects of doubled CO2 are considered, the stressed yields should increase by 17–18%, and the potential yields by 5–14%. (v) The decrease of the
stressed yields due to the indirect effect may be reduced by applying earlier planting dates.
Received March 9, 2001 Revised September 25, 2001 相似文献
3.
Summary Estimates of spring precipitation for the inner Alpine dry valley of the upper Inn (Tyrol, Austria) are made back to A.D.
1724 using a ring width chronology of Scots pine (Pinus sylvestris L.) as predictor. A highly significant agreement in year-to-year ring width changes exists between several chronologies along
the dry valley. The dendroclimatic model used for climate reconstruction is a simple linear transfer function that estimates
April–June precipitation from current tree-ring width. All verification statistics commonly used in dendroclimatological research
are significant ( p < 0.01) and indicate that the reconstructed time series provides valuable information on past spring precipitation variability.
Reconstructed spring rainfall deficiencies and surpluses ≥ 20% compared to the long-term mean in 1819, 1832, 1834, 1865, 1885,
and in 1780, 1782, 1821, 1853, 1910, respectively, are also documented by local historical records. Furthermore, a comparison
is made with an independent climate reconstruction based on historical weather indices valid for the northern side of the
Swiss Alps. A fairly good agreement is found between both spring rainfall reconstructions at low frequency intervals during
1755–1862 and 1919–1981. This preliminary study shows that tree-rings can be used to reconstruct spring rainfall variability
for inner Alpine dry valleys.
Received December 18, 2000 Revised May 28, 2001 相似文献
4.
T. Halenka J. Kalvová Z. Chládová A. Demeterová K. Zemánková M. Belda 《Theoretical and Applied Climatology》2006,86(1-4):125-145
Summary We analyze daily precipitation and temperature extremes over the Czech Republic in a regional climate simulation for the 40-year
period of 1961–2000 carried out with the RegCM3 regional climate model. The model is run at 45 km grid interval and is driven
by NCEP/NCAR reanalysis lateral boundary conditions. Comparison with station data shows that the model performs reasonably
well in simulating the frequency of daily precipitation events of medium to high intensity as well as the precipitation intensities
(return levels) of long return periods, with the exception of mountain stations. While this is attributed mainly to the relatively
coarse representation of topography across the area of the Czech Republic, the parameterization of convection can be another
reason. The model underestimates daily maximum temperature (especially in the warm seasons) and as a result the occurrence
of heat waves (high temperature episodes). The performance of the model improves in the simulation of daily minimum temperature
and cold wave events. In order to apply this regional model to the simulation of extreme events over the complex terrain as
for Czech Republic we recommend that a higher resolution is used in order to better describe the topography of the Czech Republic
and that the daily maximum temperature bias is reduced. 相似文献
5.
Vulnerability and adaptation assessments of agriculturalcrops under climate change in the Southeastern USA 总被引:1,自引:0,他引:1
Summary It is expected that a change in climatic conditions due to global warming will directly impact agricultural production. Most
climate change studies have been applied at very large scales, in which regions were represented by only one or two weather
stations, which were mainly located at airports of major cities. The objective of this study was to determine the potential
impact of climate change at a local level, taking into account weather data recorded at remote locations. Daily weather data
for a 30-year period were obtained for more than 500 sites, representing the southeastern region of the USA. Climate change
scenarios, using transient and equilibrium global circulation models (GCM), were defined, created and applied to the daily
historical weather data. The modified temperature, precipitation and solar radiation databases corresponding to each of the
climate change scenarios were used to run the CERES v.3.5 simulation model for maize and winter wheat and the CROPGRO v.3.5
model for soybean and peanut. The GCM scenarios projected a shorter duration of the crop-growing season. Under the current
level of CO2, the GCM scenarios projected a decrease of crop yields in the 2020s. When the direct effects of CO2 were assumed in the study, the scenarios resulted in an increase in soybean and peanut yield. Under equilibrium , the GCM climate change scenarios projected a decrease of maize and winter wheat yield. The indirect effects of climate change
also tended to decrease soybean and peanut yield. However, when the direct effects of CO2 were included, most of the scenarios resulted in an increase in legume yields. Possible changes in sowing data, hybrids and
cultivar selection, and fertilization were considered as adaptation options to mitigate the potential negative impact of potential
warming.
Received July 20, 1999/Revised April 18, 2000 相似文献
6.
Z. Yan S. Bate R. E. Chandler V. Isham H. Wheater 《Theoretical and Applied Climatology》2006,83(1-4):121-137
Summary We investigate the capability of generalized linear models (GLMs) to simulate sequences of daily maximum wind speed (DMWS),
at a selection of locations in NW Europe. Models involving both the gamma and Weibull distributions have been fitted to the
NCEP reanalysis data for the period 1958–1998. In simulations, these models successfully reproduce the observed increasing
trends up to 0.3 m/s per decade in coastal or oceanic locations for the wintertime and the decreasing trends down to –0.2 m/s
per decade in inland Europe for the summertime. Annually extreme winds exhibit an increasing tendency (with median estimates
up to 0.6 m/s per decade) at the studied locations. The gamma model slightly overestimates the upper percentiles of the wind
speed distribution, but reproduces trends better than the Weibull model. In both the NCEP data and GLM simulations, local
extreme DMWS events (defined in terms of threshold exceedances) have increased dramatically in frequency during winter; decreasing
trends are more common in summer. The NCEP data indicate similar trends in the frequencies of large-scale windy events (defined
via simultaneous exceedances at 2 or more locations). Overall, these events have increased in number; at the scale of the
North Sea basin, their number may have changed from 3–5 days per year during the earlier decades, to 5–7 days per year during
later decades based on observational estimates. An increase in the frequency of large-scale extreme winter storms is implied.
The GLMs underestimate these large-scale event frequencies, and provide imprecise estimates of the corresponding secular trends.
These problems could be rectified by using a better representation of spatial dependence. The present results suggest that
GLMs offer a useful tool to study local climate extremes in the context of changing climate distributions; they also provide
some pointers towards improving the representation of extremes at a regional scale. 相似文献
7.
Xavier Fettweis Hubert Gallée Filip Lefebre Jean-Pascal van Ypersele 《Climate Dynamics》2005,24(6):623-640
The 1990 and 1991 ablation seasons over Greenland are simulated with a coupled atmosphere-snow regional climate model with
a 25-km horizontal resolution. The simulated snow water content allows a direct comparison with the satellite-derived melt
signal. The model is forced with 6-hourly ERA-40 reanalysis at its boundaries. An evaluation of the simulated precipitation
and a comparison of the modelled melt zone and the surface albedo with remote sensing observations are presented. Both the
distribution and quantity of the simulated precipitation agree with observations from coastal weather stations, estimates
from other models and the ERA-40 reanalysis. There are overestimations along the steep eastern coast, which are most likely
due to the “topographic barrier effect”. The simulated extent and time evolution of the wet snow zone compare generally well
with satellite-derived data, except during rainfall events on the ice sheet and because of a bias in the passive microwave
retrieved melt signal. Although satellite-based surface albedo retrieval is only valid in the case of clear sky, the interpolation
and the correction of these data enable us to validate the simulated albedo on the scale of the whole Greenland. These two
comparisons highlight a large sensitivity of the remote sensing observations to weather conditions. Our high-resolution climate
model was used to improve the retrieval algorithms by taking more fully into account the atmosphere variability. Finally,
the good agreement of the simulated melting surface with the improved satellite signal allows a detailed estimation of the
melting volume from the simulation. 相似文献
8.
This paper reviews recent progress in climate change attribution studies. The focus is on the attribution of observed long-term changes in surface temperature, precipitation, circulation, and extremes, as well as that of specific extreme weather and climate events. Based on new methods and better models and observations, the latest studies further verify the conclusions on climate change attribution in the IPCC AR5, and enrich the evidence for anthropogenic influences on weather and climate variables and extremes. The uncertainty of global temperature change attributable to anthropogenic forcings lies in the considerable uncertainty of estimated total radiative forcing due to aerosols, while the uncertainty of precipitation change attribution arises from the limitations of observation and model simulations along with influences from large internal variability. In terms of extreme weather and climate events, it is clear that attribution studies have provided important new insights into the changes in the intensity or frequency of some of these events caused by anthropogenic climate change. The framing of the research question, the methods selected, and the model and statistical methods used all have influences on the results and conclusions drawn in an event attribution study. Overall, attribution studies in China remain inadequate because of limited research focus and the complexity of the monsoon climate in East Asia. Attribution research in China has focused mainly on changes or events related to temperature, such as the attribution of changes in mean and extreme temperature and individual heat wave events. Some progress has also been made regarding the pattern of changes in precipitation and individual extreme rainfall events in China. Nonetheless, gaps remain with respect to the attribution of changes in extreme precipitation, circulation, and drought, as well as to the event attribution such as those related to drought and tropical cyclones. It can be expected that, with the continual development of climate models, ongoing improvements to data, and the introduction of new methods in the future, climate change attribution research will develop accordingly. Additionally, further improvement in climate change attribution will facilitate the development of operational attribution systems for extreme events, as well as attribution studies of climate change impacts. 相似文献
9.
Scott C. Sheridan Cameron C. Lee Michael J. Allen Laurence S. Kalkstein 《Climatic change》2012,115(2):291-309
Excessive heat significantly impacts the health of Californians during irregular but intense heat events. Through the 21st century, a significant increase in impact is likely, as the state experiences a changing climate as well as an aging population. To assess this impact, future heat-related mortality estimates were derived for nine metropolitan areas in the state for the remainder of the century. Here in Part I, changes in oppressive weather days and consecutive-day events are projected for future years by a synoptic climatological method. First, historical surface weather types are related to circulation patterns at 500mb and 700mb, and temperature patterns at 850mb. GCM output is then utilized to classify future circulation patterns via discriminant function analysis, and multinomial logistic regression is used to derive future surface weather type at each of six stations in California. Five different climate model-scenarios are examined. Results show a significant increase in heat events over the 21st century, with oppressive weather types potentially more than doubling in frequency, and with heat events of 2?weeks or longer becoming up to ten times more common at coastal locations. 相似文献
10.
Impact of soil moisture initialisation and lateral boundary conditions on regional climate model simulations of the West African Monsoon 总被引:3,自引:3,他引:0
In this study, we use the Met Office Hadley Centre regional climate model HadRM3P to investigate the relative impact of initial
soil moisture (SM) and lateral boundary conditions (LBC) on simulations of the West African Monsoon. Soil moisture data that
are in balance with our particular model are generated using a 10-year (1997–2007) simulation of HadRM3P nested within the
NCEP-R2 reanalyses. Three sets of experiments are then performed for six April–October seasons (2000 and 2003–2007) to assess
the sensitivity to different sources of initial SM data and lateral boundary data. The results show that the only impact of
the initial SM anomalies on precipitation is to generate small random intraseasonal, interannual and spatial variations. In
comparison, the influence of the LBC dominates both in terms of magnitude and spatial coherency. Nevertheless, other sources
of initial SM data or other models may respond differently, so it is recommended that the robustness of this conclusion is
established using other model configurations. 相似文献
11.
Potential for added value to downscaled climate extremes over Korea by increased resolution of a regional climate model 总被引:1,自引:0,他引:1
This study estimates the potential for added value in dynamical downscaling by increasing the spatial resolution of the regional climate model (RCM) over Korea. The Global/Regional Integrated Model System—Regional Model Program with two different resolutions is employed as the RCM. Large-scale forcing is given by a historical simulation of a global climate model, namely the Hadley Center Global Environmental Model version 2. As a standard procedure, the reproducibility of the RCM results for the present climate is evaluated against the reanalysis and observation datasets. It is confirmed that the RCM adequately reproduces the major characteristics of the observed atmospheric conditions and the increased resolution of the RCM contributes to the improvement of simulated surface variables including precipitation and temperature. For the added-value assessment, the interannual and daily variabilities of precipitation, temperature are compared between the different resolution RCM experiments. It is distinctly shown that variabilities are additionally described as the spatial resolution becomes higher. The increased resolution also contributes to capture the extreme weather conditions, such as heavy rainfall events and sweltering days. The enhanced added value is more evident for the precipitation than for the temperature, which stands for a usefulness of the high-resolution RCM especially for diagnosing potential hazard related to heavy rainfall. The results of this study assure the effectiveness of increasing spatial resolution of the RCM for detecting climate extremes and also provide credibility to the current climate simulation for future projection studies. 相似文献
12.
Future change of climate in South America in the late twenty-first century: intercomparison of scenarios from three regional climate models 总被引:2,自引:1,他引:1
Jose A. Marengo Tercio Ambrizzi Rosmeri P. da Rocha Lincoln M. Alves Santiago V. Cuadra Maria C. Valverde Roger R. Torres Daniel C. Santos Simone E. T. Ferraz 《Climate Dynamics》2010,35(6):1073-1097
Regional climate change projections for the last half of the twenty-first century have been produced for South America, as
part of the CREAS (Cenarios REgionalizados de Clima Futuro da America do Sul) regional project. Three regional climate models
RCMs (Eta CCS, RegCM3 and HadRM3P) were nested within the HadAM3P global model. The simulations cover a 30-year period representing
present climate (1961–1990) and projections for the IPCC A2 high emission scenario for 2071–2100. The focus was on the changes
in the mean circulation and surface variables, in particular, surface air temperature and precipitation. There is a consistent
pattern of changes in circulation, rainfall and temperatures as depicted by the three models. The HadRM3P shows intensification
and a more southward position of the subtropical Pacific high, while a pattern of intensification/weakening during summer/winter
is projected by the Eta CCS/RegCM3. There is a tendency for a weakening of the subtropical westerly jet from the Eta CCS and
HadRM3P, consistent with other studies. There are indications that regions such of Northeast Brazil and central-eastern and
southern Amazonia may experience rainfall deficiency in the future, while the Northwest coast of Peru-Ecuador and northern
Argentina may experience rainfall excesses in a warmer future, and these changes may vary with the seasons. The three models
show warming in the A2 scenario stronger in the tropical region, especially in the 5°N–15°S band, both in summer and especially
in winter, reaching up to 6–8°C warmer than in the present. In southern South America, the warming in summer varies between
2 and 4°C and in winter between 3 and 5°C in the same region from the 3 models. These changes are consistent with changes
in low level circulation from the models, and they are comparable with changes in rainfall and temperature extremes reported
elsewhere. In summary, some aspects of projected future climate change are quite robust across this set of model runs for
some regions, as the Northwest coast of Peru-Ecuador, northern Argentina, Eastern Amazonia and Northeast Brazil, whereas for
other regions they are less robust as in Pantanal region of West Central and southeastern Brazil. 相似文献
13.
Summary The increasing use of weather radar quantitative precipitation estimates, particularly in automatic applications such as operational
hydrometeorological modelling or assimilation in numerical weather prediction (NWP) models, has promoted the development of
quality control procedures on radar data.
Anomalous propagation (AP) of the radar beam due to deviation from the standard refractivity vertical profile, is one of the
factors that may affect seriously the quality of radar observations because of the increase in quantity and intensity of non-precipitating
clutter echoes and consequent contamination of the estimated rainfall field. Another undesired effect of AP is the change
in the expected radar echo height, which may be relevant when correcting for beam blockage in radar rainfall estimation in
complex terrain. The aim of this paper is to study the use of NWP mesoscale forecasts to predict and monitor AP events.
A nested 15-km grid resolution version of the MASS model has been used to retrieve refractivity profiles in the coastal area
of Barcelona, near a weather radar and a radiosonde station. Using the refractivity profiles two different magnitudes were
computed: the vertical refractivity profile of the lowest 1000 m layer and a ducting index which describes the existence and
intensity of the most super-refractive layer contained in the lowest 3-km layer. A comparison between model forecasts and
radiosonde diagnostics during a six-month period showed that the model tended to underestimate the degree of super-refraction,
with a bias of 4 km−1 and RMSE of 11 km−1 in the 1-km vertical refractivity gradient. Further analysis of the data showed that a combination of previous observations
and forecasts allowed to produce modified forecasts improving the original direct model output, decreasing substantially the
bias, reducing the RMSE by 20% and improving the skill by 40%, beating also radiosonde observations persistence. 相似文献
14.
Assessing the impact of climate changes on the potential yields of maize and paddy rice in Northeast China by 2050 总被引:1,自引:0,他引:1
Luoman Pu Shuwen Zhang Jiuchun Yang Liping Chang Xiangming Xiao 《Theoretical and Applied Climatology》2020,140(1):167-182
Northeast China is the main crop production region in China, and future climate change will directly impact crop potential yields, so exploring crop potential yields under future climate scenarios in Northeast China is extremely critical for ensuring future food security. Here, this study projected the climate changes using 12 general circulation models (GCMs) under two moderate Representative Concentration Pathway (RCP) scenarios (RCP 4.5 and 6.0) from 2015 to 2050. Then, based on the Global Agro-ecological Zones (GAEZ) model, we explored the effect of climate change on the potential yields of maize and paddy rice in Northeast China during 2015–2050. The annual relative humidity increased almost throughout the Northeast China under two RCPs. The annual precipitation increased more than 400 mm in some west, east, and south areas under RCP 4.5, but decreased slightly in some areas under RCP 6.0. The annual wind speed increased over 2 m/s in the west region. The annual net solar radiation changes varied significantly with latitude, but the changes of annual maximum temperature and minimum temperature were closely related to the terrain. Under RCP 4.5, the average maize potential yield increased by 34.31% under the influence of climate changes from 2015 to 2050. The average rice potential yield increased by 16.82% from 2015 to 2050. Under RCP 6.0, the average maize and rice potential yields increased by 25.65% and 6.34% respectively. The changes of maize potential yields were positively correlated with the changes of precipitation, wind speed, and net solar radiation (the correlation coefficients were > 0.2), and negatively correlated with the changes of relative humidity, minimum and maximum temperature under two RCPs. The changes of rice potential yields were positively correlated with the changes of precipitation (correlation coefficient = 0.15) under RCP 4.5. Under RCP 6.0, it had a slight positive correlation with net solar radiation, relative humidity, and wind speed. 相似文献
15.
Present climate simulation over Korea with a regional climate model using a one-way double-nested system 总被引:1,自引:0,他引:1
Summary This study investigates the capability of the regional climate model RegCM3 to simulate surface air temperature and precipitation
over the Korean Peninsula. The model is run in one-way double nested mode, with a 60 km grid point spacing “mother” domain
encompassing the eastern regions of Asia and a 20 km grid point spacing nested domain covering the Korean Peninsula. The simulation
spans the three-year period of 1 October 2000 through 30 September 2003 and the boundary conditions needed to run the mother
domain experiment are provided from the NCEP reanalysis of observations. The model results are compared with a high density
station observation dataset to examine the fine scale structure of the surface climate signal. The model shows a good performance
in capturing both the sign and magnitude of the seasonal and inter-annual variations of the surface variables both over East
Asia as a whole and over the Korean Peninsula in the nested system. Some persistent biases are however present. Surface temperature
is systematically underestimated, especially over mountainous regions in the warm season. This feature may be due to the relatively
coarse representation of the Korean topography. The simulated precipitation over the mother domain successfully reproduces
the broad spatial pattern of observed precipitation over East Asia along with its seasonal evolution. On the other hand, fine
scale details from the nested results show a varying level of quality for the different individual years. Because of the better
resolved topographic forcing, the increased resolution of the nested model improves the spatial agreement with the fine scale
observation fields for temperature and cold season precipitation. For summer monsoon precipitation the simulation of individual
monsoon convective events and tropical storms is however more important than the topographic forcing, and therefore the performance
of the nested system is more case-dependent. 相似文献
16.
Decreasing teleconnections with inter-site distance in monthly climatic data and tree-ring width networks in a mountainous Alpine area 总被引:3,自引:0,他引:3
C. Rolland 《Theoretical and Applied Climatology》2002,71(1-2):63-75
Summary The similarities in time series recorded at sites which are distant from each other are called teleconnections. In this paper,
the loss of such correlations with inter-site distance was investigated for both climatic and dendrochronological data sets,
with 70 tree-ring chronologies. A dense network of weather stations was studied in the southeastern French Alps, covering
complex climatic gradients over three departments. 78 sites with precipitation data (with a total of 48 756 monthly values),
and 48 stations that recorded temperature (with 20 722 monthly mean values) were analysed. In the same area, four coniferous
species (mountain pine and stone pine, European larch and Norway spruce) provided 37 ring-width chronologies for high elevation
sites near the timberline. Both silver fir and Norway spruce provided a second tree-ring chronology network for 33 different
sites at lower elevations.
The teleconnections between precipitation series were found to be higher than those observed for temperature over short distances,
but the maximum threshold distance was lower (193 km) compared to a positive correlation distance that exceeds 500 km for
temperature. The maximum temperatures had stronger teleconnections than minimum values (522 km versus 476 km), since the latter
are linked more with other site factors, such as slope, exposure and local topography.
As expected, the tree-ring chronologies showed weaker teleconnections than the climatic series, with a threshold distance
of 374 km obtained for all high elevation forests. The coniferous species with high intra-specific teleconnections over large
distances were, in decreasing importance, Pinus uncinata (> 500 km), Picea abies (477 km), Pinus cembra (over 254 km) and Larix decidua (over 189 km only). The two former species showed the highest intra-specific correlations (with mean correlation R=0.625 and 0.666). The dendrochronological teleconnections were found to have a extent lesser for trees species that depend
on rainfall (such as larch, and stone pine). They are enhanced, however, for temperature sensitive species such as spruce
and mountain pine (a drought resistant tree). Therefore, these two latter conifers appear to be especially suitable for climatic
reconstruction over large distances in mountainous areas. However, teleconnections within silver fir (Abies alba) and spruce chronologies were sharply reduced (over 131 km and 135 km) in lower elevation forests, underlining the interest
of timberline forests for dendroclimatology.
A better knowledge of the spatial correlations in climatic series and ring-width data may enable the optimisation of weather
station networks. It may also permit a better choice of weather stations used for dendroclimatology, either for tree-ring
and climate relationship calibration or for climate reconstructions. In dendrochronology, wood dating also requires the knowledge
of to what extent remote ring-width chronologies can be used.
Received September 11, 2000 Revised March 26, 2001 相似文献
17.
Statistical downscaling of daily mean temperature, pan evaporation and precipitation for climate change scenarios in Haihe River, China 总被引:6,自引:1,他引:5
A statistical downscaling method (SDSM) was evaluated by simultaneously downscaling air temperature, evaporation, and precipitation in Haihe River basin, China. The data used for evaluation were large-scale atmospheric data encompassing daily NCEP/NCAR reanalysis data and the daily mean climate model results for scenarios A2 and B2 of the HadCM3 model. Selected as climate variables for downscaling were measured daily mean air temperature, pan evaporation, and precipitation data (1961–2000) from 11 weather stations in the Haihe River basin. The results obtained from SDSM showed that: (1) the pattern of change in and numerical values of the climate variables can be reasonably simulated, with the coefficients of determination between observed and downscaled mean temperature, pan evaporation, and precipitation being 99%, 93%, and 73%, respectively; (2) systematic errors existed in simulating extreme events, but the results were acceptable for practical applications; and (3) the mean air temperature would increase by about 0.7°C during 2011~2040; the total annual precipitation would decrease by about 7% in A2 scenario but increase by about 4% in B2 scenario; and there were no apparent changes in pan evaporation. It was concluded that in the next 30 years, climate would be warmer and drier, extreme events could be more intense, and autumn might be the most distinct season among all the changes. 相似文献
18.
Michelle T. H. van Vliet Stephen Blenkinsop Aidan Burton Colin Harpham Hans Peter Broers Hayley J. Fowler 《Climatic change》2012,111(2):249-277
Regional or local scale hydrological impact studies require high resolution climate change scenarios which should incorporate
some assessment of uncertainties in future climate projections. This paper describes a method used to produce a multi-model
ensemble of multivariate weather simulations including spatial–temporal rainfall scenarios and single-site temperature and
potential evapotranspiration scenarios for hydrological impact assessment in the Dommel catchment (1,350 km2) in The Netherlands and Belgium. A multi-site stochastic rainfall model combined with a rainfall conditioned weather generator
have been used for the first time with the change factor approach to downscale projections of change derived from eight Regional
Climate Model (RCM) experiments for the SRES A2 emission scenario for the period 2071–2100. For winter, all downscaled scenarios
show an increase in mean daily precipitation (catchment average change of +9% to +40%) and typically an increase in the proportion
of wet days, while for summer a decrease in mean daily precipitation (−16% to −57%) and proportion of wet days is projected.
The range of projected mean temperature is 7.7°C to 9.1°C for winter and 19.9°C to 23.3°C for summer, relative to means for
the control period (1961–1990) of 3.8°C and 16.8°C, respectively. Mean annual potential evapotranspiration is projected to
increase by between +17% and +36%. The magnitude and seasonal distribution of changes in the downscaled climate change projections
are strongly influenced by the General Circulation Model (GCM) providing boundary conditions for the RCM experiments. Therefore,
a multi-model ensemble of climate change scenarios based on different RCMs and GCMs provides more robust estimates of precipitation,
temperature and evapotranspiration for hydrological impact assessments, at both regional and local scale. 相似文献
19.
S. Hofinger G. J. Mayr E. Dreiseitl M. Kuhn 《Meteorology and Atmospheric Physics》2000,72(2-4):175-184
Summary ?Intra-mountain summertime precipitation was studied in the Alps in a 40×20 km2 area centered around Innsbruck, Austria, from June through September 1997. An observational network with a mean separation
distance of 9 km and forecasts from the ECMWF model were used to examine the role the strong forcing from the lower boundary
plays in creating “hot spots” for the formation of thunderstorms and the location of heavy precipitation as well as systematic
precipitation patterns for different weather situations, which can be used to downscale forecasts from global scale routine
numerical weather prediction models.
Received March 16, 1999/Revised August 20, 1999 相似文献
20.
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
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