A comprehensive model inter-comparison study investigating the water budget during the BALTEX-PIDCAP period

Summary A comparison of 8 regional atmospheric model systems was carried out for a three-month late summer/early autumn period in 1995 over the Baltic Sea and its catchment area. All models were configured on a common grid using similar surface and lateral boundary conditions, and ran in either data assimilation mode (short term forecasts plus data assimilation), forecast mode (short term forecasts initialised daily with analyses) or climate mode (no re-initialisation of model interior during entire simulation period). Model results presented in this paper were generally post processed as daily averaged quantities, separate for land and sea areas when relevant. Post processed output was compared against available analyses or observations of cloud cover, precipitation, vertically integrated atmospheric specific humidity, runoff, surface radiation and near surface synoptic observations. The definition of a common grid and lateral forcing resulted in a high degree of agreement among the participating model results for most cases. Models operated in climate mode generally displayed slightly larger deviations from the observations than the data assimilation or forecast mode integration, but in all cases synoptic events were well captured. Correspondence to near surface synoptic quantities was good. Significant disagreement between model results was shown in particular for cloud cover and the radiative properties, average precipitation and runoff. Problems with choosing appropriate initial soil moisture conditions from a common initial soil moisture field resulted in a wide range of evaporation and sensible heat flux values during the first few weeks of the simulations, but better agreement was shown at later times. Received September 8, 2000 Revised April 3, 2001     

Application of remote sensing and multivariate analysis to the agroclimatic characterization of a Mediterranean region

Summary This paper presents a climatological application of the combination of remote sensing data and multivariate analysis. It proposes a methodology to perform an agroclimatic characterization of a region with the aim of determining homogeneous areas. This methodology is applied to Catalonia, in the northwest of the Mediterranean Sea, in the Iberian Peninsula. To this end various multivariate analysis techniques have been applied to data from 107 meteorological stations and to digitally processed AVHRR images from a NOAA satellite (ground surface temperature and thermal inertia). Values of emissivity and albedo for different land uses and phenomenological states, in addition to the most suitable algorithms for the soil surface temperature, have been obtained. Combining this information with orographic characteristics and the Papadakis classification, a final map is obtained with 68 homogeneous zones for the period between April and October, the most important for the agriculture of the area studied.With 5 Figures     

GNSS remote sensing of the Australian tropopause

Radio occultation (RO) techniques that use signals transmitted by Global Navigation Satellite Systems (GNSS) have emerged over the past decade as an important tool for measuring global changes in tropopause temperature and height, a valuable capacity given the tropopause??s sensitivity to temperature variations. This study uses 45,091 RO data from the CHAMP (CHAllenging Minisatellite Payload, 80 months), GRACE (Gravity Recovery And Climate Experiment, 23 months) and COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate, 20 months) satellites to analyse the variability of the tropopause??s height and temperature over Australia. GNSS RO temperature profiles from CHAMP, GRACE, and COSMIC are first validated using radiosonde observations provided by the Bureau of Meteorology (Australia). These are compared to RO soundings from between 2001 and 2007 that occurred within 3 h and 100 km of a radiosonde. The results indicate that RO soundings provide data of a comparable quality to radiosonde observations in the tropopause region, with temperature deviations of less than 0.5 ± 1.5 K. An analysis of tropopause height and temperature anomalies indicates a height increase over Australia as a whole of ca. 4.8 ± 1.3 m between September 2001 and April 2008, with a corresponding temperature decrease of ?0.019 ± 0.007 K. A similar pattern of increasing height/decreasing temperature was generally observed when determining the spatial distribution of the tropopause height and temperature rate of change over Australia. Although only a short period has been considered in this study, a function of the operating time of these satellites, the results nonetheless show an increase in the height of the tropopause over Australia during this period and thus may indicate regional warming. Several mechanisms could be responsible for these changes, such as an increase in the concentration of greenhouse gases in the atmosphere, and lower stratospheric cooling due to ozone loss, both of which have been observed during the last decades.     

SL-AV atmospheric model version using σ-<Emphasis Type="Italic">p</Emphasis> hybrid vertical coordinates

The SL-AV atmospheric model version using hybrid vertical coordinates combies the advantages of sigma and isobaric coordinates. The formulation and discretization of model equations maintain the equivalency of the new model version to the basic sigma version in the special case, when hybrid coordinates coincide with sigma coordinates. The SL-AV model version with hybrid vertical coordinate is verified with medium-range weather forecasts. The decrease in the errors of predicted geopotential height and wind as compared to the sigma model version is demonstrated. The use of hybrid coordinates also leads to a certain increase in forecast skill scores for some meteorological parameters characterizing aviation significant weather.     

Projected impact of deep ocean carbon dioxide discharge on atmospheric CO2 concentrations

An evaluation of oceanic containment strategies for anthropogenic carbon dioxide is presented. Energy conservation is also addressed through an input hydrocarbon-fuel consumption function. The effectiveness of the proposed countermeasures is determined from atmospheric CO₂ concentration predictions. A previous box model with a diffusive deep ocean is adapted and applied to the concept of fractional CO₂ injection in 500 m deep waters. Next, the contributions of oceanic calcium carbonate sediment dissolution, and of deep seawater renewal, are included. Numerical results show that for CO₂ direct removal measures to be effective, large fractions of anthropogenic carbon dioxide have to be processed. This point favors fuel pre-processing concepts. The global model also indicates that energy conservation, i.e. a hydrocarbon-fuel consumption slowdown, remains the most effective way to mitigate the greenhouse effect, because it offers mankind a substantial time delay to implement new energy production alternatives.     

荒漠化,干旱与植被—以西非萨赫勒为例

关于西非荒漠化的本质和特征存在着许多看法。该文将追溯其历史，回顾荒漠化对气候影响的研究现状，并介绍一些有关研究结果。对荒漠化的认识通常为“沙漠”的扩张，是一个总体上不可逆转的人为过程。其过程与地表反照率增强，风沙加大以及土地生产力下降相联系。研究表明，在最近１６年里撒哈拉沙漠的边界和萨赫勒植被均变化不大，从植被水分有效利用率来看，“生产力”没有系统性降低，地表反照率也没有多少改变。自２０世纪５０年     

Computation of maximum water temperature in the Beloyarskoe Reservoir

Presented is a three-dimensional model for computing hydrothermodynamic processes in the Beloyarskoe Reservoir used as a basin-cooler of the Beloyarskaya nuclear power plant. In view of the designing of new power units for the station and due to the absence of reliable reservoir-analogs in the region under consideration, the computation is carried out of the distribution of maximum water temperature in the reservoir for natural conditions. The results of these computations are subsequently used as background parameters for designing a system of technical water supply of NPP and for the ecological feasibility report.     

震后快速钻探:历史、现状与未来

大地震发生后立即在断层带上进行钻探可以帮助我们获取更多的地震信息,尤其是可获得决定断层动态破裂的摩擦水平和强度,观测断层的愈合过程及可能触发余震的应力变化,并可获取控制破裂过程的重要的物理和化学属性。在2008年11月由国际大陆科学钻探项目（ICDP）和南加州地震中心（SCEC）联合在日本东京举办的为期3天的“震后快速钻探：历史、现状与未来”研讨会上,     

Petrologic evolution of Krakatau (Indonesia): Implications for a future activity

Krakatau Volcano is located along a N35E volcanic lineament running through the Sunda straits (Indonesia). Its last activity has been characterized by successive phases, each beginning with the construction of a cone, and ending with its destruction and the formation of a caldera. The two last (pre- and post-1883) cycles are well known, but the more ancient ones are not so clearly defined.Lavas of Krakatau belong to an andesitic series, in which fractional crystallization plays the most important role. The petrologic evolution is characterized by a cyclicity in good agreement with the structural evolution: the succession is regular: basalts, basic andesites, acid andesites, dacites. A gap between acid and basic andesites occurs in each cycle. The destructive stages correspond to the occurrence of dacitic terms.The Anak cycle was characterized from 1927 to 1979 by basalts and basic andesites; the 1981 eruption involved a more differentiated magma (close to dacitic). Detailed study of the petrologic evolution since 1883 emphasizes the predominant role of fractional crystallization. This process occurred during a very short period, between 1979 and 1981. Separation of labradorite, augite, olivine and magnetite from parental basic andesite may generate the dacitic descendant, in a shallow reservoir (P_H2O estimated about 0.5 kbar). Implications for a future activity are considered.     

Surface Synoptic Circulation and Daily Precipitation in Catalonia

Summary Catalonian daily precipitation patterns were obtained by means of S-mode Principal Component Analysis (PCA) applied to subsets built up according to synoptic surface airflow. Daily data from November to April 1990–1994 from 45 raingauge sites in Catalonia without missing data were used. Eight circulation classes for days in this period were considered. A Precipitation Activity Index (PAI) was calculated for each station and class, leading to the determination of the highest activity regions for each subset. In addition, we determined which circulation type produced most precipitation at each station of the network. Separate PCAs were performed for each of the eight classes considered and the first four Varimax rotated solutions were interpreted for each circulation type. The physical meaning of the rest of the factors were omitted as they were associated with local behaviour. Finally, some concluding remarks on the cyclogenic properties of the Western Mediterranean Basin and the diversity of the extracted patterns are presented and supported by the authors experience in forecasting in Catalonia. Received February, 11, 1997 Revised May 23, 1997