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High resolution regional climate model simulations for Germany: Part II—projected climate changes 总被引:1,自引:1,他引:0
The projected climate change signals of a five-member high resolution ensemble, based on two global climate models (GCMs: ECHAM5 and CCCma3) and two regional climate models (RCMs: CLM and WRF) are analysed in this paper (Part II of a two part paper). In Part I the performance of the models for the control period are presented. The RCMs use a two nest procedure over Europe and Germany with a final spatial resolution of 7 km to downscale the GCM simulations for the present (1971–2000) and future A1B scenario (2021–2050) time periods. The ensemble was extended by earlier simulations with the RCM REMO (driven by ECHAM5, two realisations) at a slightly coarser resolution. The climate change signals are evaluated and tested for significance for mean values and the seasonal cycles of temperature and precipitation, as well as for the intensity distribution of precipitation and the numbers of dry days and dry periods. All GCMs project a significant warming over Europe on seasonal and annual scales and the projected warming of the GCMs is retained in both nests of the RCMs, however, with added small variations. The mean warming over Germany of all ensemble members for the fine nest is in the range of 0.8 and 1.3 K with an average of 1.1 K. For mean annual precipitation the climate change signal varies in the range of ?2 to 9 % over Germany within the ensemble. Changes in the number of wet days are projected in the range of ±4 % on the annual scale for the future time period. For the probability distribution of precipitation intensity, a decrease of lower intensities and an increase of moderate and higher intensities is projected by most ensemble members. For the mean values, the results indicate that the projected temperature change signal is caused mainly by the GCM and its initial condition (realisation), with little impact from the RCM. For precipitation, in addition, the RCM affects the climate change signal significantly. 相似文献
75.
Abstract The purpose of this article is to analyse whether the presence of surplus emission allowance trading jeopardizes the environmental target of an international environmental agreement. We argue that surplus emission allowance trading can be used as an implicit side-payment mechanism to actually bring about higher environmental protection compared with the situation without the trade option. We point to the existence of a fundamental trade-off between costs of compliance and the creation of dynamic incentives to develop cheaper reduction technologies. Implicit side payments, in terms of surplus emission allocations, may be needed in order to establish a compromise between these opposing demands. We identify the shortcomings and benefits of allowing fully flexible permit trading, including the allocation rule of grandfathering. 相似文献
76.
Gamma-ray background counting rates encountered in astronomy observations are calculated for a double Compton scatter telescope. Backgrounds not eliminated by the usual growth curve could be produced by albedo neutrons and/or cosmic ray protons interacting with the carbon and/or hydrogen of the detector. They are the albedo neutron-carbon interaction gamma-rays, cosmic ray proton interaction delayed gamma rays and the moderated albedo neutron-proton photocapture gamma rays. It is decisive to know the contribution of these backgrounds, because they must be subtracted before the cosmic diffuse flux can be determined. Estimates of the neutron induced background events in a Compton telescope show that they might contribute a considerable fraction of the counting rate. In the near future the calculations will be checked with a calibrated neutron beam. 相似文献
77.
78.
Gabriella Sch?ll-Barna Attila Demény Gábor Serlegi Szilvia Fábián Pál Sümegi István Fórizs Bernadett Bajnóczi 《Journal of Paleolimnology》2012,47(1):87-100
Geochemical records of bivalve shells have been increasingly studied in the last decade to obtain information on climate conditions.
In this paper we present stable isotope compositions of living and prehistoric shells of freshwater mussels (Unionidae) and
their relationships with climate conditions in a shallow lake environment of Lake Balaton, West-Central Hungary. Physical
conditions and stable oxygen isotope compositions of lake water samples were monitored where living bivalves were collected.
Comparisons between seasonal variations in ambient temperature, water composition and within-shell isotopic variations indicate
that the shells of Unio pictorum do reflect local changes at high resolution and thus can be used to study past conditions. Additionally, shells covering
the last two decades were gathered at several locations along the lake in order to determine spatial and temporal variations
in the shells’ isotopic compositions as a function of weather conditions. As an application, prehistoric shells collected
in archaeological excavations were analysed in order to study past environmental variations. Climate variations during the
Late Copper Age (5460–4870 cal. yr BP) have been assumed on the basis of geomorphological and archaeozoological observations
at the site Balatonkeresztúr-Réti-dűlő (south of Lake Balaton), that suggested increasing humidity as a cause of changes in
settlement location and domestic livestock husbandry. Stable carbon and oxygen isotope compositions of prehistoric bivalve
shells were analyzed from excavations representing five archaeological subphases (Boleráz subphase, 5460–5310 cal. yr BP;
two transitional subphases around 5310 cal. yr BP; Early Classic subphase, 5310–5060 cal. yr BP; Late Classic subphase, 5040–4870 cal.
yr BP). The analyses revealed significant negative C and O isotope shifts in the transitional subphases relative to the earlier
and later subphases. The isotopic variations indicate that the local climate became relatively wet and possibly cold around
5310 cal. yr BP, then it returned to drier (and likely warmer) conditions during the Classic subphases. This interpretation
is in agreement with previous studies on climate changes related to the “5.3 ky event” in the European continental area and
the North Atlantic Region, indicating an Atlantic influence in the Carpathian Basin. 相似文献
79.
Elevation gradients of European climate change in the regional climate model COSMO-CLM 总被引:1,自引:0,他引:1
A transient climate scenario experiment of the regional climate model COSMO-CLM is analyzed to assess the elevation dependency
of 21st century European climate change. A focus is put on near-surface conditions. Model evaluation reveals that COSMO-CLM
is able to approximately reproduce the observed altitudinal variation of 2 m temperature and precipitation in most regions
and most seasons. The analysis of climate change signals suggests that 21st century climate change might considerably depend
on elevation. Over most parts of Europe and in most seasons, near-surface warming significantly increases with elevation.
This is consistent with the simulated changes of the free-tropospheric air temperature, but can only be fully explained by
taking into account regional-scale processes involving the land surface. In winter and spring, the anomalous high-elevation
warming is typically connected to a decrease in the number of snow days and the snow-albedo feedback. Further factors are
changes in cloud cover and soil moisture and the proximity of low-elevation regions to the sea. The amplified warming at high
elevations becomes apparent during the first half of the 21st century and results in a general decrease of near-surface lapse
rates. It does not imply an early detection potential of large-scale temperature changes. For precipitation, only few consistent
signals arise. In many regions precipitation changes show a pronounced elevation dependency but the details strongly depend
on the season and the region under consideration. There is a tendency towards a larger relative decrease of summer precipitation
at low elevations, but there are exceptions to this as well. 相似文献
80.
We derive a conceptual model of the flow over heterogeneous terrain consisting of patches with contrasting Bowen ratios. Upward
moving eddies are assumed to carry heterogeneous properties, whereas downward moving eddies carry homogeneous properties.
This results in a decorrelation of temperature and humidity as the contrast between the patches increases. We show that this
model is able to reproduce the relationship developed by Lamaud and Irvine (Boundary-Layer Meteorol. 120:87–109, 2006). Some
details differ from their expression but are in accordance with data obtained over African savannah. We extend the conceptual
model to a combination of any scalars, not necessarily linked through the surface energy balance (as is the case for temperature
and humidity). To this end we introduce a new parameter that describes the surface heterogeneity in surface fluxes. The results
of the current model can be used to predict the discrepancy between similarity relationships for different scalars over heterogeneous
terrain. 相似文献