A model evaluation approach is proposed in which weather and climate prediction models are analyzed along a Pacific Ocean cross section, from the stratocumulus regions off the coast of California, ...across the shallow convection dominated trade winds, to the deep convection regions of the ITCZ—the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/WGNE) Pacific Cross-Section Intercomparison (GPCI). The main goal of GPCI is to evaluate and help understand and improve the representation of tropical and subtropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross section from the subtropics to the tropics for the season June–July–August of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the 40-yr ECMWF Re-Analysis (ERA-40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical cross sections of cloud properties (in particular), vertical velocity, and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA-40 in the stratocumulus regions as compared to the first International Satellite Cloud Climatology Project (ISCCP) is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too early along the trade wind Lagrangian trajectory. Histograms of cloud cover along the cross section differ significantly between models. Some models exhibit a quasi-bimodal structure with cloud cover being either very large (close to 100%) or very small, while other models show a more continuous transition. The ISCCP observations suggest that reality is in-between these two extreme examples. These different patterns reflect the diverse nature of the cloud, boundary layer, and convection parameterizations in the participating weather and climate prediction models.
Precipitation simulated using the Regional Spectral Model (RSM) during the Coordinated Enhanced Observing Period (CEOP; July 1, 2001 to December 31, 2004) is evaluated by transferring the RSM to ...seven different regions of the globe and comparing the simulations with observations. These regions cover the eight Continental-Scale Experiments (CSEs) of the Global Energy and Water-cycle EXperiment (GEWEX) and encompass a broad variety of physical and dynamical meteorological processes. Gridded observations of the Global Precipitation Climatology Project (GPCP) and the Global Precipitation Climatology Center (GPCC), as well as CEOP reference site precipitation observations are compared with the RSM simulated precipitation for the first half of the CEOP Enhanced Observation Period (EOP) III (October 2002 to March 2003). After estimating the uncertainty ranges of both the model and the observations, model deficiencies were obtained for almost all model domains in terms of the amount of simulated precipitation. Although the RSM is able to accurately simulate the seasonal evolution and spatial distribution of precipitation, the RSM has an almost uniform positive bias (i.e., RSM values are greater than observed values) over almost all the domains. Most of the positive bias is associated with convection in the Intertropical Convergence Zone (ITCZ) or monsoonal convection in Southeast Asia. Predicted stratiform precipitation is also excessive over areas ofelevated topography. As the control simulations used a Relaxed Arakawa-Schubert scheme (RAS), sensitivity tests with three additional convection schemes were then carried out to assess whether the simulations could be improved. The additional convection schemes were: 1) the Simplified Arakawa-Schubert scheme (SAS); 2) the Kain-Fritsch scheme (KF); and 3) the National Centers for Atmospheric Research (NCAR) Community Climate Model (CCM) scheme. The precipitation simulation was significantly improved for almost all domains when using either the KF scheme or the SAS scheme. The best simulations of ITCZ convective precipitation and Southeast Asian monsoon convective precipitation were achieved using the SAS convection scheme.
In this study, categories, dimensions, and criteria for evaluating regional climate services are derived by a participatory approach with potential service users at the German Baltic Sea coast. The ...development is carried out within nine face-to-face interviews conducted with decision makers, working in climate sensitive sectors at the German Baltic Sea coast. Three main groups of categories were localized which seem to matter most to the considered stakeholders and which seem to be crucial evaluation categories for regional climate services: (1) credibility, (2) relevance, and (3) appropriateness. For each of these evaluation categories several dimensions emerged, indicating certain perspectives of stakeholder demands. When summarizing these evaluation categories and their dimensions, 13 evaluation criteria for regional climate services can be derived (see Table 1). The results show that stakeholders do mainly address components other than those found in the literature (e.g. inputs, process, outputs, outcomes, and impacts). This might indicate that an evaluation, following solely literature-based (non-participative) components, is not sufficient to localize deficiencies or efficiencies within a regional climate service, since it might lead to results which are not relevant for potential users.
In this article the comparability of knowledge transfer activities is discussed by accounting for external impacts. It is shown that factors which are neither part of the knowledge transfer activity ...nor part of the participating institution may have significant impact on the potential usefulness of knowledge transfer activities. Differences in the potential usefulness are leading to different initial conditions of the knowledge transfer activities. This needs to be taken into account when comparing different knowledge transfer activities, e.g., in program evaluations. This study is focusing on regional climate services at the German Baltic Sea coast. It is based on two surveys and experiences with two identical web tools applied on two regions with different spatial coverage. The results show that comparability among science based knowledge transfer activities is strongly limited through several external impacts. The potential usefulness and thus the initial condition of a particular knowledge transfer activity strongly depends on (1) the perceived priority of the focused topic, (2) the used information channels, (3) the conformity between the research agenda of service providing institutions and information demands in the public, as well as (4) on the spatial coverage of a service. It is suggested to account for the described external impacts for evaluations of knowledge transfer activities. The results show that the comparability of knowledge transfer activities is limited and challenge the adequacy of quantitative measures in this context. Moreover, as shown in this case study, in particular regional climate services should be individually evaluated on a long term perspective, by potential user groups and/or by its real users. It is further suggested that evaluation criteria should be co-developed with these stakeholder groups.
Coastal research deals with that part of the sea, which is significantly affected by the land, and the part of the land, which is significantly affected by the sea. Coasts are in most cases densely ...populated, and the activities of people are shaping and changing the land/seascape of the coast. Thus, coast encompasses the coastal sea, the coastal land, coastal flora and fauna, and people. Since peoples’ economic and political preferences change and compete, the human impact on the coast changes is contested and subject to societal decision making processes.
While some coastal research can help informing and constraining such decisions, many legitimate scientific efforts have little bearing on society. All decision making processes are political, so that scientific knowledge is not the dominant driver in such processes. Using cases from the Institute of Coastal Research of Helmholtz Zentrum Geesthacht, we describe some of these potentially useful parts of science, and discuss under which circumstances the potential usefulness transform into real utility. These cases do not span the full range of coastal science.
Important issues are the recognition of alternative knowledge claims, the inevitableness of uncertainties and incompleteness of scientific analysis, the acceptance of the political nature of decisions and the ubiquitous presence of social values. Modesty, self-reflexivity and skepticism are needed on the side of science and an organized exchange with stakeholders and public through designated “border” services.
An evaluation of the cloud parameterization scheme in the High-Resolution Regional Model (HRM) of the Deutscher Wetterdienst was conducted using data from the International Satellite Cloud ...Climatology Project (ISCCP). Uncertainties in the model and in the measurements were first quantified. Then, criteria for comparisons of simulated and measured data were chosen in order to identify model deficiencies. The simulated clouds were subsequently classified by their parameterization so model deficiencies could be easily attributed to a certain parameterization scheme. Following this evaluation, an overestimation of simulated mean cloud amount was identified as a deficiency of the HRM. The overestimation occurred mainly during the night and was due to an overprediction of subscale clouds at low-level emissivity heights. At medium-level emissivity heights during the day, the cloud amount is underpredicted. This leads to an underestimation of the diurnal cycle. These deficiencies were connected with the relative humidity parameterization used to characterize subscale cloudiness. PUBLICATION ABSTRACT
The impact of spectral nudging on cloud simulation with a regional atmospheric model was examined. Simulated cloudiness of the Regional Model (REMO) and the Spectrally Nudged REMO (SN-REMO) were ...intercompared and evaluated with satellite-derived cloudiness from the International Satellite Cloud Climatology Project (ISCCP). In general, the additional spectral nudging does not affect the mean cloud simulation. However, for particular weather regimes the introduction of spectral nudging causes notable differences in cloud simulation. Two weather conditions for these large differences in cloud simulation were derived: 1) change of the general circulation patterns, or 2) strong anticyclonic circulation within the model domain. Case studies of these weather situations indicated a better agreement of simulated and satellite-derived cloudiness when spectral nudging has been applied to the regional model. PUBLICATION ABSTRACT
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