Bent Hansen Sass

This paper describes a novel scheme for assessing the ability of a numerical weather prediction (NWP) model to forecast the horizontal spatial structure of local extremes, for example, when comparing accumulated precipitation to a corresponding observed field. Both local maxima and minima are considered. The quality is measured by a score function...

In the simulation of complex multi-scale flows arising in weather and climate modelling, one of the biggest challenges is to satisfy strict service requirements in terms of time to solution and to satisfy budgetary constraints in terms of energy to solution, without compromising the accuracy and stability of the application. These simulations requi...

In December 2018, the Danish Meteorological Institute organised an international meeting on the subject of crowdsourced data in numerical weather prediction (NWP) and weather forecasting. The meeting, spanning 2 days, gathered experts on crowdsourced data from both meteorological institutes and universities from Europe and the United States. Scient...

In the simulation of complex multi-scale flow problems, such as those arising in weather and climate modelling, one of the biggest challenges is to satisfy operational requirements in terms of time-to-solution and energy-to-solution yet without compromising the accuracy and stability of the calculation. These competing factors require the developme...

The Environment – High Resolution Limited Area Model (Enviro-HIRLAM) is developed as a fully online integrated numerical weather prediction (NWP) and atmospheric chemical transport (ACT) model for research and forecasting of joint meteorological, chemical and biological weather. The integrated modelling system is developed by the Danish Meteorologi...

This paper provides an overview of the HLRADIA shortwave (SW) and longwave (LW) broadband radiation schemes used in the HIRLAM numerical weather prediction (NWP) model and available in the HARMONIE-AROME mesoscale NWP model. The advantage of broadband, over spectral, schemes is that they can be called more frequently within the model, without compr...

The aim of this article is to describe the reference configuration of the convection-permitting numerical weather prediction (NWP) model HARMONIE-AROME, which is used for operational short-range weather forecasts in Denmark, Estonia, Finland, Iceland, Ireland, Lithuania, the Netherlands, Norway, Spain, and Sweden. It is developed, maintained, and v...

Abstracts of European Geosciences Union (EGU) General Assembly, 23-28 Apr 2017, Vienna, Austria; Geophysical Research Abstracts, Vol.19, EGU2017-8477-1

The Environment – HIgh Resolution Limited Area Model (Enviro-HIRLAM) is developed as a fully online integrated numerical weather prediction (NWP) and atmospheric chemical transport (ACT) model for research and forecasting of joint meteorological, chemical and biological weather. The integrated modelling system is developed by DMI in collaboration w...

Programme and Abstracts of the 1st ESCAPE Dissemination and Training Workshop on "Towards Energy-efficient Scalable Algorithms for Weather- and Climate Prediction: Status and Prospects", 21 p., 18-20 Oct 2016, Elsinore, Denmark The workshop sessions will be organized according to the following topics (with oral presentations, including keynote spea...

Covered period July 2015 – Jun 2016: Project progress report on Enviro-HIRLAM and HARMONIE models studies

Abstracts of European Geosciences Union (EGU) General Assembly, 17-22 Apr 2016, Vienna, Austria; Geophysical Research Abstracts, Vol.18, EGU2016-10130

Abstracts of European Geosciences Union (EGU) General Assembly, 17-22 Apr 2016, Vienna, Austria; Geophysical Research Abstracts, Vol.18, EGU2016-1404

Programme and Abstracts of the 3rd CRAICC-PEEX Workshop on "Climate Change for Arctic Seas and Shipping", 15 p., 24-25 Aug 2015, Copenhagen, Denmark The topics of this workshop are: --- estimating consequences of climate change for the Arctic region on seas and shipping and effects of ship emissions on the environment and climate; --- estimating fr...

At the Danish Meteorological Institute, the NWP nowcasting system has been enhanced to include assimilation of 2D precipitation rates derived from weather radar observations. The assimilation is performed using a nudging-based technique. Here the rain rates are used to estimate the changes in the vertical profile of horizontal divergence needed to...

Abstracts of European Geosciences Union (EGU) General Assembly, 12-17 Apr 2015, Vienna, Austria; Geophysical Research Abstracts, Vol.17, EGU2015-1545

A new approach for assimilation of 2D precipitation in numerical weather prediction models is presented and tested in a case with convective, heavy precipitation. In the scheme a nudging term is added to the horizontal velocity divergence tendency equation. In case of underproduction of precipitation, the strength of the nudging is proportional to...

Abstracts of European Geosciences Union (EGU) General Assembly, 27 Apr – 2 May 2014, Vienna, Austria; Geophysical Research Abstracts, Vol.16, EGU2014-5238

Abstracts of European Geosciences Union (EGU) General Assembly, 27 Apr – 2 May 2014, Vienna, Austria; Geophysical Research Abstracts, Vol.16, EGU2014-5277

Enviro-HIRLAM is developed as a fully online coupled numerical weather prediction (NWP) and Chemical Transport model for research and forecasting of joint meteorological, chemical and biological weather. The integrated modelling system is developed by DMI and other collaborators (Chenevez et al., 2004; Baklanov et al., 2008a, 2011b; Korsholm et al....

Enviro-HIRLAM is developing as a fully online-coupled numerical weather prediction (NWP) and chemistry transport model (CTM) for research and forecasting. The integrated modeling system is developed mainly by DMI as well as other collaborators and included by the HIRLAM consortium as the baseline system in the HIRLAM Chemical Branch. During the las...

The method for statistical correction of the air/ road surface temperatures forecasts was developed based on analysis of long-term time-series of meteorological observations and forecasts (from HIRLAM-SKA/ RCM models outputs) and tested for May-Aug 2012/ Oct 2012 - Mar 2013 periods. For the city weather applications, new operationalized procedure f...

The main aim of this study is to improve forecasted 2 meter air temperature from the numerical weather prediction (NWP) model (called – HIRLAM – High Resolution Limited Area Model) output. The specific objectives are: 1) study behavior in the errors (biases) for selected Danish synoptical stations, where 2m air temperature is measured; and 2) propo...

Abstracts of European Meteorological Society (EMS) Annual Meeting, 10-14 Sep 2012, Lodz, Poland, Vol.9, EMS2012-192

Abstracts of European Meteorological Society (EMS) Annual Meeting, 10-14 Sep 2012, Lodz, Poland, Vol.9, EMS2012-190

The system, which can provide operational forecasts of the road surface temperature, air temperature and dew point temperature for any road stretch in Denmark, has been developed, tested and verified. Detailed local characteristics influencing shadowing effects for road stretches were obtained from the high resolution Danish databases on terrain, o...

Abstracts of European Geosciences Union (EGU) General Assembly, 22-27 Apr 2012, Vienna, Austria; Geophysical Research Abstracts, Vol.14, EGU2012-10887 The signature of climate change on European surface ozone was studied using the online integrated climate-chemistry model for Environmental applications (EnvClimA). The EnvClimA is an environmental v...

The approach for statistical correction of the road surface temperature (Ts) for the first 5 hours forecast lengths was developed. It is based on a statistics of Ts bias variability (within three intervals: negative, ±0.1°C, and positive) considering average, median and mode values of the bias. Hierarchy of importance of forecasted meteorological p...

The vehicles measurements of the road conditions (so-called thermal mapping data, ThMD) have been used for verification of the performance of the Danish Road Weather Modelling System (RWMS) at road stretches of selected roads and compared with forecasts at selected road stations of the Danish road network. It was found that the RWMS system showed a...

The DMI has in collaboration with the Danish Road Directorate (DRD) for almost two decades used a Road Condition Model (RCM) system (based on a dense road observations network and the numerical weather prediction model - HIgh Resolution Limited Area Model, HIRLAM) to provide operational forecasts of main road conditions at selected road stations of...

Forecasting of slippery road conditions is the important product delivered by the Danish Meteorological Institute in collaboration with the Danish Road Directorate. In order to avoid accident at slippery roads preventing salting must be taken. A balance on how much and where exactly this measure should be taken have become of critical importance fo...

Many experimental studies and research simulations show that atmospheric processes (meteorological weather, including the precipitation, thunderstorms, radiation budget, cloud processes, and boundary layer structure) depend on concentrations of chemical species (especially aerosols) in the atmosphere. In order to improve the quality of daily operat...

The most serious air pollution events occur in cities where there is a combination of high population density and air pollution from vehicles. The contaminants can lead to serious human health problems, including asthma, irritation of the lungs, bronchitis, pneumonia, decreased resistance to respiratory infections, and premature death. In particula...

For the road weather season (1 October – 1 May) 2009/2010, the scores for the 3 hour forecasts of the road surface temperature with an error of less than ±1ºC is almost 83%, based on more than 473 thousand corresponding forecasts. The overall seasonal averages of the bias and mean absolute error are +0.02ºC and 0.69ºC. This is an improvement compar...

Abstracts of European Geosciences Union (EGU) General Assembly, 2-7 May 2010, Vienna, Austria; Geophysical Research Abstracts, Vol.12, EGU2010-314 The most serious air pollution events occur in cities where there is a combination of high population density and air pollution, e.g. from vehicles. The pollutants can lead to serious human health probl...

There is a balance between doing to much or too little preventing salting to avoid slippery roads. Both for environmental and economical reasons it pays off to make all possible efforts to find out if salting is necessary. For these reasons an interest for road stretch forecasts has been growing recently. The requirements to make these very accurat...

The variability of the road surface temperature (Ts) BIAS and MAE on a scale of the road weather season and on a monthly scale was analyzed applying various classifications of the road stations. These were based on: (i) positioning or placement near/at the driving lanes (in airport areas, on bridges and near the roads); (ii) urban related environme...

The DMI has in collaboration with the Danish Road Directorate (DRD) for almost two decades used a Road Condition Model (RCM) system (based on a dense road observations network and the numerical weather prediction model-HIgh Resolution Limited Area Model, HIRLAM) to provide operational forecasts of main road conditions at selected road stations of t...

The operational road weather forecasts performed by the DMI Road Weather Modelling (RWM) system is an important product for the end-user community. As input, the continuous observations from synoptic weather and road stations of the Danish national road network along with meteorological output from the DMI's numerical weather prediction High Resolu...

The DMI has in collaboration with the Danish Road Directorate (DRD) for almost two decades used a Road Condition Model (RCM) system (based on a dense road observations network and the numerical weather prediction model - HIgh Resolution Limited Area Model, HIRLAM) to provide operational forecasts of main road conditions at selected road stations of...

For the last road weather season (1 October – 1 May) 2008/2009, the scores for the 3 hour forecasts of the road surface temperature with an error of less than ±1ºC is almost 80%, based on more than 519 thousand corresponding forecasts. The overall seasonal averages of the bias and mean absolute error are -0.11ºC and 0.76ºC. This is comparable to se...

Evaluation of the road icing conditions in the Danish road network was conducted based on observational data (road surface, air and dew point temperatures) from 2003-2007 road weather seasons from the road stations. The red alert situations (representing the highest risk of icing conditions on the roads) and warning situations (representing a high...

Chemical weather is a field of increasing popularity and several institutes, such as Environment Canada and NOAA, currently forecast both chemical and meteorological weather. Following a definition (Lawrence et al., 2005), chemical weather may be given as local, regional and global distributions of trace gases and aerosols with corresponding variab...

Abstracts of 8th Annual Meeting of European Meteorological Society and European Conference on Applied Climatology, 29 Sep – 3 Oct 2008, Amsterdam, Netherlands; Vol. 5, EMS2008-A-00456

For the last road weather season (1 October – 1 May) 2007/2008, the scores for the 3 hour forecasts of the road surface temperature with an error of less than ±1ºC is almost 81%, respectively, based on more than 442 thousand corresponding forecasts. The overall seasonal averages of the bias and mean absolute error are 0.18ºC and 0.78ºC for the last...

It is an ultimate goal to deliver accurate forecasts for every locations. At the moment DMI is able to deliver accurate point forecasts for a limited number of places along the Danish road network. All these locations are equipped with measuring instruments which provide a numerical model with initial conditions for the road surface. A project at D...

The DMI is delivering accurate point forecasts for a limited number of places (i.e. road stations) along the Danish road network. All these locations are equipped with special measuring instruments which provide a numerical model with initial conditions for the road surface. DMI is developing such system in a way that it can make forecasts not only...

The prediction of mesoscale weather phenomena, such as local winds and heavy precipitation, has always been a big challenge because of their direct impact on people's lives. In recent years computer power has increased enough to make it possible to run regional numerical weather forecast models for the prediction of local weather. This paper descri...

In this study, which is a part of the VIKING-6 project, the vehicles measurements of the road conditions (road surface and air temperatures - thermal mapping data) from Ribe and Vestsjælland Communes roads (VA-4, RI-1, GR-2, and 102-KS-L) have been used for verification of performance of the Danish Road Weather Model (RWM) system. During 2006-2007...

The road weather forecasts done by the DMI RoadWeather Modelling (RWM) system is an important operational product. After each season the evaluation of the performance of the Road Conditions Model (RCM) is conducted in order to continue further development and improvement of the system and model. This system uses as input the continuous observations...

Due to increased resolution in the numerical weather prediction models, assimilation of satellite cloud related data on an hourly basis, and integration of measurements of road conditions from road maintenance vehicles allowed to improve quality and accuracy of road weather forecasting. The DMI Road Weather Modelling (RWM) system uses these changes...

Improvements in performance of the Danish Road Weather Model system due to incorporation and assimilation of cloud observations from satellites and conventional data are discussed. Both conventional observations and NOAA and MSG-1 satellite data were assimilated using a nudging technique and the results were verified for a two weeks period. Additio...

Abstracts of 6th Annual Meeting of European Meteorological Society (EMS), 3-7 Sep 2006, Ljubljana, Slovenia; Vol.3, EMS2006-A-00485

Improvements in performance of the Danish Road Weather Model system due to incorporation and assimilation of cloud observations from satellites and conventional data are discussed. Both conventional observations and NOAA and MSG-1 satellite data were assimilated using a nudging technique and the results were verified for a two weeks period. Additio...

Results of modifications and improvements in the road weather forecasting using high resolution satellite cloud data are shown. For test phase, the air temperate and dew point as well as road surface temperature are evaluated and verified during the period of 1-14 March 2005. Satellite data for cloud cover are evaluated against ground observations...

This report describes the May 2005 upgrade of DMI’s operational forecast system DMI-HIRLAM and results of numerical experiments.

Abstract The production of a realistic `Ekman pumping' in numerical models of the atmosphere poses a signi�cant problem. A method is presented to tune a turbulence scheme of a given model to improve the behaviour of the boundary layer �flow with respect to the Ekman pumping. It is shown for an idealized barotropic boundary layer that a clockwise tu...

ABSTRACTA severe cyclone with destructive effects moved across Denmark during the evening of 3 December 1999. A study, based on a numerical high-resolution limited area model simulation of this event, is presented. The development is of the frontal wave type. It can be interpreted qualitatively as an interaction between a PV wave at the tropopause,...

A severe cyclone with destructive effects moved across Denmark during the evening of 3 December1999. A study, based on a numerical high-resolution limited area model simulation of this event,is presented. The development is of the frontal wave type. It can be interpreted qualitatively as aninteraction between a PV wave at the tropopause, a surface...

This documentation covers in some parts alternativeschemes, e.g. for analysis or convective parameterisation and this has been done for completeness, as either scheme may be used by Hirlam members

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 assimil...

A numerical weather prediction system "DMI-HIRLAM" is run operationally at the Danish Meteorological Institute (DMI). The goal of the DMI weather prediction system is to provide high accuracy meteorological forecast products, with a special priority on forecasts valid for the short range, up to about two days ahead. The system provides guidance to...

Simulated time series of the total precipitable water (PW) vapor from a limited area numerical weather prediction model are compared to estimates derived from observations done with ground-based Global Positioning System (GPS) receivers. The model data examined are from the delayed-mode High Resolution Limited Area Model (HIRLAM) data assimilation...

Introduction The Road Conditions Model #RCM# is a vitally important operational product. It is therefore relevanttoevaluate the performance of the RCM. In addition, users of the system havevoiced interest in gaining access to a veri#cation report after each slippery road season. For a detailed description of the RCM, see Bent Hansen Sass's article,...

Simulated time series of the vertically integrated atmospheric water vapor (IWV) from a numerical weather prediction (NWP) HIgh Resolution Limited Area Model (HIRLAM), are compared to the data derived from measurements by the ground based global positioning system (GPS) receivers at twenty five sites in Sweden and Finland, for a four month period....

A numerical forecasting system is presented for automatic prediction of slippery road conditions at road station sites in Denmark. The system is based on a road conditions model forced by input from an operational atmospheric limited area model. Synoptic information on cloud cover and observations of temperature and humidity from the road station s...

Times Cited: 9

A numerical model for the prediction of road temperature and ice has been tested on data from a Danish road station. The model is based on the solution of the equation of heat conduction in the ground and the surface energy-balance equation.Sensitivity experiments have been carried out in order to assess the relative importance of the various activ...

Abstract The issue of analysing and predicting cloud cover accurately is considered in the con- text of the numerical road condition model ‘ROCMO’ (ROad Condition MOdel) used operationally at the Danish Meteorological Institute (DMI). A procedure for analysing cloud cover is presented. The analysis is based on the combination of information from sy...

1. The model setup At the Danish Meteorological Institute (DMI) the atmospheric limited area model DMI-HIRLAM (Sass et al. 2002) is used in a special setup to produce very short range forecasts of cloud cover, precipitation, 2m temperature, dew point and road surface temperture for many (≈ 370) road-weather stations in Denmark. New forecasts are pr...