Kooperativer Bibliotheksverbund

Berlin Brandenburg

and
and

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Language
Year
  • 1
    Language: English
    In: Meteorology and Atmospheric Physics, 2009, Vol.104(3), pp.135-162
    Description: The representation of a simulated synoptic-scale weather system is compared with observations. To force the model to the observed state, the so-called Newtonian relaxation technique (nudging) is applied to relax vorticity, divergence, temperature, and the logarithm of surface pressure to the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis fields. The development of an extraordinary strong cyclone along the East Coast of the USA during 12–14 March 1993 was chosen as the case study. The synoptic-scale features were well represented in the model simulation. However, systematic differences to observations of the International Satellite Cloud Climatology Project (ISCCP) occurred. The model underestimated clouds in lower and middle levels of the troposphere. Low-level clouds were mainly underestimated behind the cold front of the developing cyclone, while the underestimation of mid-level clouds seems to be a more general feature. The reason for the latter is the fact that the relative humidity has to exceed a critical threshold before clouds can develop. In contrast, thin upper-level cirrus clouds in pre-frontal regions were systematically overestimated by the model. Therefore, we investigated the effects of changed physical parameterizations with two sensitivity studies. In the PCI experiment, the standard cloud scheme operated in ECHAM4 was replaced by a more sophisticated one which defines separate prognostic equations for cloud liquid water and cloud ice. The second experiment, RHCRIT, changed the profile of the critical relative humidity threshold for the development of clouds in the standard scheme. Both experiments showed positive changes in the representation of clouds during the development of the cyclone as compared to the ISCCP. PCI clearly reduced the upper-level cloud amounts by intensifying the precipitation flux in the middle troposphere. The changed condensation threshold in the RHCRIT experiment led to a sharper represented cold front and a better represented cloudiness on its rear side as compared to the PCI and the CONTROL simulations.
    Keywords: Humidity -- Case Studies ; Humidity -- Models ; Humidity -- Methods ; Humidity -- Analysis ; Rain -- Case Studies ; Rain -- Models ; Rain -- Methods ; Rain -- Analysis ; Weather -- Case Studies ; Weather -- Models ; Weather -- Methods ; Weather -- Analysis ; Cirrus Clouds -- Case Studies ; Cirrus Clouds -- Models ; Cirrus Clouds -- Methods ; Cirrus Clouds -- Analysis ; Relaxation Techniques (Psychology) -- Case Studies ; Relaxation Techniques (Psychology) -- Models ; Relaxation Techniques (Psychology) -- Methods ; Relaxation Techniques (Psychology) -- Analysis ; Biogeochemical Cycles -- Case Studies ; Biogeochemical Cycles -- Models ; Biogeochemical Cycles -- Methods ; Biogeochemical Cycles -- Analysis ; Water Cycle -- Case Studies ; Water Cycle -- Models ; Water Cycle -- Methods ; Water Cycle -- Analysis ; Troposphere -- Case Studies ; Troposphere -- Models ; Troposphere -- Methods ; Troposphere -- Analysis;
    ISSN: 0177-7971
    E-ISSN: 1436-5065
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Language: English
    In: PLoS ONE, 01 January 2015, Vol.10(4), p.e0123811
    Description: To achieve more realistic simulations, meteorologists develop and use models with increasing spatial and temporal resolution. The analyzing, comparing, and visualizing of resulting simulations becomes more and more challenging due to the growing amounts and multifaceted character of the data. Various data sources, numerous variables and multiple simulations lead to a complex database. Although a variety of software exists suited for the visualization of meteorological data, none of them fulfills all of the typical domain-specific requirements: support for quasi-standard data formats and different grid types, standard visualization techniques for scalar and vector data, visualization of the context (e.g., topography) and other static data, support for multiple presentation devices used in modern sciences (e.g., virtual reality), a user-friendly interface, and suitability for cooperative work.Instead of attempting to develop yet another new visualization system to fulfill all possible needs in this application domain, our approach is to provide a flexible workflow that combines different existing state-of-the-art visualization software components in order to hide the complexity of 3D data visualization tools from the end user. To complete the workflow and to enable the domain scientists to interactively visualize their data without advanced skills in 3D visualization systems, we developed a lightweight custom visualization application (MEVA - multifaceted environmental data visualization application) that supports the most relevant visualization and interaction techniques and can be easily deployed. Specifically, our workflow combines a variety of different data abstraction methods provided by a state-of-the-art 3D visualization application with the interaction and presentation features of a computer-games engine. Our customized application includes solutions for the analysis of multirun data, specifically with respect to data uncertainty and differences between simulation runs. In an iterative development process, our easy-to-use application was developed in close cooperation with meteorologists and visualization experts. The usability of the application has been validated with user tests. We report on how this application supports the users to prove and disprove existing hypotheses and discover new insights. In addition, the application has been used at public events to communicate research results.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Language: English
    In: Climate Dynamics, 2013, Vol.41(3), pp.755-774
    Description: The Weather Research and Forecast (WRF) model with its land surface model NOAH was set up and applied as regional climate model over Europe. It was forced with the latest ERA-interim reanalysis data from 1989 to 2008 and operated with 0.33° and 0.11° resolution. This study focuses on the verification of monthly and seasonal mean precipitation over Germany, where a high quality precipitation dataset of the German Weather Service is available. In particular, the precipitation is studied in the orographic terrain of southwestern Germany and the dry lowlands of northeastern Germany. In both regions precipitation data is very important for end users such as hydrologists and farmers. Both WRF simulations show a systematic positive precipitation bias not apparent in ERA-interim and an overestimation of wet day frequency. The downscaling experiment improved the annual cycle of the precipitation intensity, which is underestimated by ERA-interim. Normalized Taylor diagrams, i.e., those discarding the systematic bias by normalizing the quantities, demonstrate that downscaling with WRF provides a better spatial distribution than the ERA interim precipitation analyses in southwestern Germany and most of the whole of Germany but degrades the results for northeastern Germany. At the applied model resolution of 0.11°, WRF shows typical systematic errors of RCMs in orographic terrain such as the windward–lee effect. A convection permitting case study set up for summer 2007 improved the precipitation simulations with respect to the location of precipitation maxima in the mountainous regions and the spatial correlation of precipitation. This result indicates the high value of regional climate simulations on the convection-permitting scale.
    Keywords: Regional climate model ; Germany ; Precipitation ; Convection-permitting simulation
    ISSN: 0930-7575
    E-ISSN: 1432-0894
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Language: English
    In: Quarterly Journal of the Royal Meteorological Society, 01/2011, Vol.137(S1), pp.156-175
    Description: The impact of assimilating conventional and Global Positioning System (GPS) Zenith Total Delay (ZTD) data over France into the Weather Research and Forecasting (WRF) model is investigated during COPS IOP 9c. A convection-permitting horizontal resolution of 3.6 km covering the whole of central Europe was chosen. Four different simulations were conducted to show the influence of assimilating different observation types on the forecast. Additionally, a comparison with the models COSMO-DE and COSMO-EU from the German Meteorological Service (DWD) was performed. The results show a clear positive impact of assimilating data into a convection-permitting configuration of the WRF model over Europe. The additional assimilation of GPS-ZTD data shows a further improvement of integrated water vapour (IWV) correlation, but the influence on prediction of precipitation was not necessarily clear. A comparison with radiosonde data shows a positive impact on the humidity structure after 12 hours, while an overestimation of precipitation still remains. A further comparison with the operational high-resolution models of DWD during this COPS IOP reveals a strong dependence on the initial boundary-layer wind field especially as the near-surface wind field is better represented in the ECMWF analysis than in the COSMO analysis. As this is, to our knowledge, the first study applying a convection-permitting configuration of WRF over Europe, it can be used as a guidance for further studies.
    Keywords: Numerical Simulations ; German Meteorological Service ; European Centre for Medium-Range Weather Forecasts ; Humidity ; Global Positioning System (Gps) Satellite ; Radiosonde Data ; Precipitation ; Wind Fields ; Data Assimilation ; France ; Forecasting (551.509.1/.5);
    ISSN: Quarterly Journal of the Royal Meteorological Society
    ISSN: 1477870X
    E-ISSN: 00359009
    E-ISSN: 1477870X
    Source: Wiley (via CrossRef)
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Language: English
    In: Journal of Applied Meteorology and Climatology, 2014, Vol.53(5), pp.1143-1169
    Description: ABSTRACT Recent advances in technology permit the irrigation of dry, coastal areas, avoiding the use of fossil water and conflicts with other land use (e.g., for food production). Consequently, it becomes reasonable to consider large-scale plantations for mitigating increases in atmospheric concentrations by carbon sequestration and to study local modifications of weather and climate. This work investigates the impact of plantations in Oman and the Sonora Desert in Mexico assuming an area of about 100km × 100 km. For this purpose, an advanced land surface–atmosphere model was adapted to the local changes of land cover and operated on the convection-permitting scale. Explicit simulations of the impact of the plantation on soil–vegetation–atmosphere feedback were performed for a duration of 1 yr. A strong modification of diurnal cycles of variables such as surface fluxes, temperature, and boundary layer depth was found. Over the plantations, the mean temperature decreased as a result of nonlinear changes of the diurnal cycle caused by less warming during the day than cooling during the night. Moreover, the plantations caused an increase in vertical instability and a modification of the horizontal flow leading to the development of convergence zones. During several isolated cases in summer, this process led to convection initiation and precipitation with an enhancement of about 30mmin both areas, respectively. These convection-permitting simulations lend confidence that an increase in precipitation could be induced at the mesoscale by the introduction of vegetation in desert regions. Furthermore, this effect should be included in a quantitative assessment of climate engineering by afforestation.
    Keywords: Meteorology ; Climate Change ; Plantations ; Geoengineering ; Hydrologic Cycle;
    ISSN: 15588424
    E-ISSN: 15588432
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Language: English
    In: Journal of the Meteorological Society of Japan. Ser. II, 2018, Vol.96A(0), pp.157-174
    Description: 〈p〉 In the preparation for polarimetric radar data assimilation, it is essential to examine the accuracy of forward operators based on different formulations. For this purpose, four forward operators that focus on warm rain conditions are compared both with each other and actual observations with respect to their performance for C-band dual polarimetric radars. These operators mutually consider radar beam broadening and climatological beam bending. The first operator derives polarimetric parameters assuming an exponential raindrop size distribution obtained by the models and is based on fitting functions against scattering amplitudes. The other three converters estimate the mixing ratio of rainwater from the measured polarimetric parameters. The second converter uses both the horizontal reflectivity (〈i〉Z〈/i〉〈sub〉H〈/sub〉) and the differential reflectivity (〈i〉Z〈/i〉〈sub〉DR〈/sub〉), the third uses the specific differential phase (〈i〉K〈/i〉〈sub〉DP〈/sub〉), and the fourth uses both 〈i〉K〈/i〉〈sub〉DP〈/sub〉 and 〈i〉Z〈/i〉〈sub〉DR〈/sub〉, respectively. Comparisons with modeled measurements show that the accuracy of the third converter is superior to the other two. Another evaluation with actual observations shows that the first converter has slightly higher fractions skill scores than the other three. Considering the attenuation effect, the fitting function and the operator only with 〈i〉K〈/i〉〈sub〉DP〈/sub〉 are found to be the most suitable for data assimilation at C-band.〈/p〉
    Keywords: Data Assimilation ; Polarimetric Radar ; Evaluation
    ISSN: 0026-1165
    E-ISSN: 21869057
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    In: Tellus A, 03/2011
    ISSN: 0280-6495
    E-ISSN: 1600-0870
    Source: CrossRef
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Language: English
    In: Geoscientific Model Development Discussions, 08/29/2016, pp.1-46
    Description: The impact of a convection permitting (CP) northern hemisphere latitude-belt simulation with the Weather Research and Forecasting (WRF) model was investigated during the July and August 2013. For this application, the WRF model together with the NOAH land-surface model (LSM) was applied at two different horizontal resolutions, 0.03° (HIRES) and 0.12° (LOWRES). The set-up as a latitude-belt domain avoids disturbances that originate from the western and eastern boundaries and therefore allows to study the impact of model resolution and physical parameterizations on the results. Both simulations were forced by ECMWF operational analysis data at the northern and southern domain boundaries and the high-resolution Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) data at the sea surface. The simulations are compared to the operational ECMWF analysis for the representation of large scale features. To compare the simulated precipitation, the operational ECMWF forecast, the CPC MORPHing (CMORPH), and the ENSEMBLES gridded observation precipitation data set (E-OBS) were used.〈br〉〈br〉 Compared to the operational high-resolution ECMWF analysis, both simulations are able to capture the large scale circulation pattern though the strength of the Pacific high is considerably overestimated in the LOWRES simulation. Major differences between ECMWF and WRF occur during July 2013 when the lower resolution simulation shows a significant negative bias over the North Atlantic which is not observed in the CP simulation. The analysis indicates deficiencies in the applied combinations of cloud microphysics and convection parametrization on the coarser grid scale in subpolar regions. The overall representation of the 500 hPa geopotential height surface is also improved by the CP simulation compared to the LOWRES simulation apart across Newfoundland where the geopotential height is higher than in the LOWRES simulation due to a northward shift of the location of the Atlantic high pressure system.〈br〉〈br〉 Both simulations show higher wind speeds in the boundary layer by about 1.5 m s〈sup〉−1〈/sup〉 compared to the the ECMWF analysis. Due to the higher surface evaporation, this results in a moist bias of 0.5 g kg〈sup〉−1〈/sup〉 at 925 hPa in the planetary boundary layer compared to the ECMWF analysis. Major differences between ECMWF and WRF occur in the simulation of the 2-m temperatures over the Asian desert and steppe regions. They are significantly higher in WRF by about 5 K both during day- and night-time presumably as a result of different soil hydraulic parameters used in the NOAH land surface model for steppe regions.〈br〉〈br〉 The precipitation of the HIRES simulation shows a better spatial agreement with CMORPH especially over mountainous terrain. The overall bias reduces from 80 mm at the coarser resolution to 50 mm in the HIRES simulation and the root mean square error is reduced by about 35 % when compared to the CMORPH precipitation analysis. The precipitation distribution agrees much better with the CMORPH data than the LOWRES simulation which tends to overestimate precipitation, mainly caused by the convection parametrization. Especially over Europe the CP resolution reduces the precipitation bias by about 30 % to 20 mm as a result of a better terrain representation and due to the avoidance of the convection parameterization.
    Keywords: Geology;
    ISSN: Geoscientific Model Development Discussions
    E-ISSN: 1991-962X
    Source: CrossRef
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Language: English
    In: Geoscientific Model Development, May 31, 2017, Vol.10(5), p.2031
    Description: Increasing computational resources and the demands of impact modelers, stake holders, and society envision seasonal and climate simulations with the convection-permitting resolution. So far such a resolution is only achieved with a limited-area model whose results are impacted by zonal and meridional boundaries. Here, we present the setup of a latitude-belt domain that reduces disturbances originating from the western and eastern boundaries and therefore allows for studying the impact of model resolution and physical parameterization. The Weather Research and Forecasting (WRF) model coupled to the NOAH land-surface model was operated during July and August 2013 at two different horizontal resolutions, namely 0.03 (HIRES) and 0.12#xB0; (LOWRES). Both simulations were forced by the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis data at the northern and southern domain boundaries, and the high-resolution Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) data at the sea surface.The simulations are compared to the operational ECMWF analysis for the representation of large-scale features. To analyze the simulated precipitation, the operational ECMWF forecast, the CPC MORPHing (CMORPH), and the ENSEMBLES gridded observation precipitation data set (E-OBS) were used as references.Analyzing pressure, geopotential height, wind, and temperature fields as well as precipitation revealed (1)#xC2;#xA0;a benefit from the higher resolution concerning the reduction of monthly biases, root mean square error, and an improved Pearson skill score, and (2)#xC2;#xA0;deficiencies in the physical parameterizations leading to notable biases in distinct regions like the polar Atlantic for the LOWRES simulation, the North Pacific, and Inner Mongolia for both resolutions.In summary, the application of a latitude belt on a convection-permitting resolution shows promising results that are beneficial for future seasonal forecasting.
    Keywords: Climate Models – Usage ; Atmospheric Circulation – Models ; Precipitation (Meteorology) – Models
    ISSN: 1991-959X
    ISSN: 19919603
    E-ISSN: 19919603
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Language: English
    In: Tellus A: Dynamic Meteorology and Oceanography, 01 January 2011, Vol.63(2), pp.263-282
    Description: A forward operator for Global Positioning System (GPS) slant total delay (STD) data and its adjoint were implemented into the Mesoscale Model version 5 (MM5) 4DVAR system to investigate its impact on quantitative precipitation forecasting (QPF)....
    Keywords: Meteorology & Climatology
    E-ISSN: 1600-0870
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. Further information can be found on the KOBV privacy pages