Abstract. Radiative transfer calculations in numerical weather prediction (NWP) and climate models require reliable information about aerosol concentration in the atmosphere, combined with data on aerosol optical properties. Replacement of the default input data on vertically integrated climatological aerosol optical depth at 550 nm (AOD550, Tegen climatology) with newer data, based on those available from Copernicus atmosphere monitoring service (CAMS), led to minor differences in the simulated solar irradiance and screen-level temperature in the regional climate model HCLIM-ALARO simulations over Scandinavia and in a clear-sky case study using HARMONIE-AROME NWP model over the Iberian peninsula. In the case study, replacement of the climatological AOD550 with that based on three-dimensional near-real-time aerosol mass mixing ratio resulted in a maximum reduction of the order of 150 W m−2 in the simulated local solar irradiance at noon. Corresponding maximum reduction of the screen-level temperature by almost two degrees was found. The large differences were due to a dust intrusion from Sahara, which is obviously not represented in the average climatological distribution of dust aerosol. Further studies are needed in order to introdude updated aerosol optical properties of all available aerosol types at different wavelengths, make them available for the radiation schemes of ALADIN-HIRLAM and test the impact on the predicted radiation fluxes.

The direct radiative effect of aerosols is taken into account in many limited-area numerical weather prediction models using wavelength-dependent aerosol optical depths of a range of aerosol species. We studied the impact of aerosol distribution and optical properties on radiative transfer, based on climatological and more realistic near real-time aerosol data. Sensitivity tests were carried out using the single-column version of the ALADIN-HIRLAM numerical weather prediction system, set up to use the HLRADIA simple broadband radiation scheme. The tests were restricted to clear-sky cases to avoid the complication of cloud-radiation-aerosol interactions. The largest differences in radiative fluxes and heating rates were found to be due to different aerosol loads. When the loads are large, the radiative fluxes and heating rates are sensitive to the aerosol inherent optical properties and the vertical distribution of the aerosol species. In such cases, regional weather models should use external real-time aerosol data for radiation parametrizations. Impacts of aerosols on shortwave radiation dominate longwave impacts. Sensitivity experiments indicated the important effects of highly absorbing black carbon aerosols and strongly scattering desert dust.Atmosphere 2020, 11, 205 2 of 27 life cycle of aerosols from their formation to their deposition and their dispersion in the atmosphere at timescales of the order of several days. In such models the physicochemical processes evolve in an environment controlled by atmospheric large-scale dynamics. Advanced data assimilation, using reliable information about emission sources and conventional and space-born observations, is used to constrain the modelled processes. The Copernicus Atmosphere Monitoring Service (CAMS) global reanalysis of atmospheric composition [7] has resulted in an extensive historical aerosol dataset. They also produce global forecasts of aerosols and atmospheric chemical constituents in near-real time [8].In the European Centre for Medium-Range Weather Forecast (ECMWF) model the use of a new global 3D aerosol climatology based on [7], combined with updated aerosol inherent optical properties (IOPs), led to a systematic improvement in lower troposphere temperature and wind forecasts over certain regions of the globe [9]. However, during wildfires, desert dust intrusions, volcanic eruptions and enhanced anthropogenic emissions aerosol concentrations in the atmosphere may significantly exceed climatological values, which can influence the weather on local to global scales. In such cases reliance on aerosol climatologies is insufficient for accurate forecasting of radiation and temperatures [10][11][12][13]. Recent studies, such as those by [14,15], provide additional motivation to improve how aerosols are taken into account in short-range regional numerical weather prediction (NWP) models and not just in global medium-range forecasting and climate models [16][17][18]. The direct radiative effect of aerosols on weather and climate is much better quantified t...

La convección es uno de los fenómenos meteorológicos más difíciles de predecir. Los modelos numéricos no hidrostáticos que se integran a escalas convectivas o convection-permitting han supuesto una mejora significativa en la simulación de la convección comparados con los modelos de escala sinóptica, que necesitan parametrizar la convección profunda. Se estudia el comportamiento de los modelos HARMONIE-AROME y del IFS del Centro Europeo de Predicción a Medio Plazo (ECMWF) utilizando métodos objetivos como la verificación puntual y la verificación espacial, así como métodos subjetivos. Se ve que los modelos convection-permitting como HARMONIE-AROME reproducen mucho mejor el ciclo diurno de la precipitación que los modelos que parametrizan la convección profunda como el del Centro Europeo. En promedio, el ciclo 40 obtiene mejores resultados que el ciclo 38 tanto con la verificación puntual como con la verificación espacial. El ciclo 38 tiende a producir más actividad convectiva y también a producir más falsas alarmas. Otro resultado interesante es que la resolución efectiva de HARMONIE para la precipitación parece estar en torno a los 50 km.

Los modelos numéricos de la atmósfera son muy útiles para la predicción del tiempo a corto y medio plazo. La comunidad científica dentro del campo de la meteorología destina gran cantidad de recursos humanos y técnicos al desarrollo de los modelos de predicción numérica con el objetivo de lograr perfeccionar el pronóstico.Estos modelos de predicción constituyen una representación físico-matemática de la atmósfera, complementados con el uso de las observaciones existentes en el momento de iniciar el pronóstico del estado futuro de la atmósfera.Hoy día, las salidas de los modelos de predicción numérica del tiempo son utilizadas diariamente por pare de los predictores en los servicios meteorológicos. Por ello, es necesario conocer las características físicas y dinámicas en las que se basan estos modelos, para así, poder interpretar correctamente sus resultados.Desde junio de 2017, HARMONIE-AROME es el nuevo modelo operativo de alta resolución de AEMET. Es un modelo No-Hidrostático que resuelve la convección profunda explícitamente y que se integra con una resolución horizontal de 2.5 km. Se presenta en estas jornadas de la AME las principales características del nuevo modelo.

This study concerns the impact of microphysics on the HARMONIE-AROME NWP model. In particular, the representation of cloud droplets in the single-moment bulk microphysics scheme is examined in relation to fog forecasting. We focus on the shape parameters of the cloud droplet size distribution and recent changes to the representation of the cloud droplet number concentration (CDNC). Two configurations of CDNC are considered: a profile that varies with height and a constant one. These aspects are examined together since few studies have considered their combined impact during fog situations. We present a set of six experiments performed for two non-idealised three-dimensional case studies over the Iberian Peninsula and the North Sea. One case displays both low clouds and fog, and the other shows a persistent fog field above sea. The experiments highlight the importance of the considered parameters that affect droplet sedimentation, which plays a key role in modelled fog. We show that none of the considered configurations can simultaneously represent all aspects of both cases. Hence, continued efforts are needed to introduce relationships between the governing parameters and the relevant atmospheric conditions.