105 research outputs found
RACMO regional climate model data, postprocessed for winter precipitation and winter temperature
No full textThis contains statistics of winter precipitation and winter temperature derived from the 16 model ensemble by RACMO2. In addition to the GCM driven runs, also a PGW (pseudo global warming) set is given. Data is used for a paper to be submitted.
Reference on the RACMO2 runs: Aalbers EE, Lenderink G, van Meijgaard E, van den Hurk BJJM (2018) Local-scale changes in mean and heavy precipitation in Western Europe, climate change or internal variability? Climate Dynamics 50:4745–4766. https://doi.org/10.1007/s00382-017-3901-
(Table 2) Mass balance of different sectors in Antarctica in 1996 and 2006
No full textMass balance (net) calculated as input (accumulation) minus outflow (discharge). Net+: mass balance scaled on the basis of total area versus area surveyed
(Table 1) Mass balance of different sectors in Antarctica in 2000
No full textArea: area surveyed. Glacier discharge: grounding-line ice flux of surveyed area. Mass balance (net) calculated as input (accumulation) minus outflow (discharge). Net+: mass balance scaled on the basis of total area (area+) versus area surveyed (area), except for basin II''. Input: snow accumulation of surveyed area, input+: total snowfall in area+
Excessive rainfall over the Belgian Ardennes in December 1993: Evaluation of model predictions
No full text
Evaluation of a regional atmospheric model for January 1993, using in situ measurements from the Antarctic
No full textThe performance of a regional atmospheric climate model (RACMO) with a
horizontal resolution of 55 km X 55 km is evaluated using measured temperature and
humidity profiles. Parameterisations of the physical processes are taken from the
EC-HAM4 general circulation model (GCM). Sea-surface temperatures and sea-ice mask
in the model are prescribed from observations. The model is forced by re-analyses
of the European Centre for Medium-range Weather Forecasts (ECMWF) at the lateral
boundaries.
We compared simulations for January 1993 with boundary-layer profiles
measured at the Swedish research station Svca (Dronning Maud Land, Antarctica) and
with radiosonde measurements made at the Georg von Neumayer (GvN) and South Polar
stations for the same period. This comparison was performed in order to study some
model characteristics before the model is used for mass-balance calculations. The
vertical temperature gradient at Svea during the night is overestimated by RACMO,
but corresponds much more closely to the observations than do the ECMWF
re-analyses. in the re-analyses a decoupling of the lowest model layer from the
higher atmosphere occurs. The differences between the absolute temperatures at the
GvN and SP stations and the absolute temperatures at the model gridpoints
corresponding most closely to these sites are less than 5°C. The humidity profiles
indicate that the model generally underestimates the turbulent transport of
moisture from the surface to higher levels.</jats:p
Evaluation of Model-Predicted Top-of-Atmosphere Radiation and Cloud Parameters over Africa with Observations from GERB and SEVIRI
No full textAbstract
This study compared the Regional Atmospheric Climate Model version 2 (RACMO) with satellite data by simultaneously looking at cloud properties and top-of-atmosphere (TOA) fluxes. This study used cloud properties retrieved from Spinning Enhanced Visible and Infrared Imager (SEVIRI) data and TOA shortwave and longwave outgoing radiative fluxes measured by one of the Geostationary Earth Radiation Budget (GERB) sensors. Both SEVIRI and GERB resolve the diurnal cycle extremely well with 96 images per day. To test the physical parameterizations of the model, RACMO was run for a domain-enclosing Africa and part of the surrounding oceans. Simulations for July 2006, forced at the lateral boundaries by ERA-Interim reanalyses, show generally accurate positioning of the various cloud regimes but also some important model–observation differences, which the authors tried to reduce by altering model parameterizations. These differences are as follows: 1) TOA albedo differences in clear-sky regions like the Sahara and southern Africa. These differences were considerably reduced by prescribing the surface albedo from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. 2) A considerable overestimation of outgoing longwave radiation within the continental ITCZ caused by the fact that modeled cirrus clouds are far too thin. 3) Underestimation by the model of cloud cover, condensed water path and albedo of the stratocumulus fields off the coast of Angola. The authors reduced these underestimations by suppressing the amount of turbulent mixing above the boundary layer, by prescribing droplet radii derived from SEVIRI data, and by assuming in-cloud horizontal homogeneity for the radiation calculations. 4) Overestimation by the model of the albedo of the trade wind cumulus fields over the Atlantic Ocean. This study argues that this overestimation is likely caused by a model overestimation of condensed water path. In general, the analyses demonstrate the power of the simultaneous evaluation of the TOA fluxes and cloud properties.</jats:p
Weather Forecasting Using GPU-Based Large-Eddy Simulations
No full textSince the advent of computers midway through the twentieth century, computational resources have increased exponentially. It is likely they will continue to do so, especially when accounting for recent trends in multicore processors. History has shown that such an increase tends to directly lead to weather and climate models that readily exploit the extra resources, improving model quality and resolution. We show that Large-Eddy Simulation (LES) models that utilize modern, accelerated (e.g., by GPU or coprocessor), parallel hardware systems can now provide turbulence-resolving numerical weather forecasts over a region the size of the Netherlands at 100-m resolution. This approach has the potential to speed the development of turbulence-resolving numerical weather prediction models.Geoscience and Remote SensingCivil Engineering and Geoscience
Response of hourly precipitation extremes to temperature and moisture perturbations: Results from a mesoscale model
No full textGeoscience & Remote SensingCivil Engineering and Geoscience
RACMO2.3p1 annual surface mass balance Antarctica (1979-2014)
No full textAnnual (1979-2014) gridded surface mass balance data for Antarctic ice sheet from the regional atmospheric climate model RACMO2.3, version p
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