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 validated as part of the shared ALADIN-HIRLAM system by a collaboration of 26 countries in Europe and northern Africa on short-range mesoscale NWP. HARMONIE-AROME is based on the model AROME developed within the ALADIN consortium. Along with the joint modeling framework, AROME was implemented and utilized in both northern and southern European conditions by the above listed countries, and this activity has led to extensive updates to the model's physical parameterizations. In this paper the authors present the differences in model dynamics and physical parameterizations compared with AROME, as well as important configuration choices of the reference, such as lateral boundary conditions, model levels, horizontal resolution, model time step, as well as topography, physiography, and aerosol databases used. Separate documentation will be provided for the atmospheric and surface data-assimilation algorithms and observation types used, as well as a separate description of the ensemble prediction system based on HARMONIE-AROME, which is called HarmonEPS.

ABSTRACT:Using 6-year data collected in a high-resolution network of 19 stations in the province of Alicante (Spain), the characteristics of sea breezes for the period 2000-2005 were studied. This study attempts to develop a multi-year climatology of sea breeze flows focusing on a Western Mediterranean coastal site. We used half-hourly meteorological records from a reference station in Alicante and sea surface temperature measurements at Albufereta beach to identify past sea breeze episodes, on the basis of an objective selection technique. A total of 475 sea breeze events during the 6-year period were identified and the following parameters were determined: mean time of onset, mean wind speed and direction at the time of onset, mean time of cessation, mean temporal dimension (duration), mean maximum velocity, mean time of maximum velocity and mean wind path of the sea breeze. The mean onset and cessation times are 0940 UTC and 2009 UTC (local standard time= UTC +0100 h, or +0200 h with daylight-saving time), respectively, with a mean duration of 1029 h. The mean wind speed at the time of the passage of sea breeze fronts is low (2.07 m s −1 ), but sea breeze gust intensities range from 3.6 to 11.6 m s −1 and they generally occur during 1200-1300 UTC. Southerly and southeasterly onset flows dominate in winter, whereas more easterly onsets occur in spring and summer. The mean inland directed wind path of the sea breezes is 97.7 km with noteworthy differences throughout the year; a case study showed onshore wind peaks of 11.1 m s −1 , 50-km inland of the Vinalopó river valley in the late afternoon. The spatial and temporal change in wind speed and direction were also analysed, using multi-year wind hodographs for the 19 stations and eight well-defined synoptic patterns favouring the development of sea breezes.

At temperate latitudes the synoptic patterns of bird migration are strongly structured by the presence of cyclones and anticyclones, both in the horizontal and altitudinal dimensions. In certain synoptic conditions, birds may efficiently cross regions with opposing surface wind by choosing a higher flight altitude with more favourable wind. We observed migratory passerines at mid-latitudes that selected high altitude wind optima on particular nights, leading to the formation of structured migration layers at varying altitude up to 3 km. Using long-term vertical profiling of bird migration by C-band Doppler radar in the Netherlands, we find that such migration layers occur nearly exclusively during spring migration in the presence of a high-pressure system. A conceptual analytic framework providing insight into the synoptic patterns of wind assistance for migrants that includes the altitudinal dimension has so far been lacking. We present a simple model for a baroclinic atmosphere that relates vertical profiles of wind assistance to the pressure and temperature patterns occurring at temperate latitudes. We show how the magnitude and direction of the large scale horizontal temperature gradient affects the relative gain in wind assistance that migrants obtain through ascending. Temperature gradients typical for northerly high-pressure systems in spring are shown to cause high altitude wind optima in the easterly sectors of anticyclones, thereby explaining the frequent observations of high altitude migration in these synoptic conditions. Given the recurring synoptic arrangements of pressure systems across temperate continents, the opportunities for exploiting high altitude wind will differ between flyways, for example between easterly and westerly oceanic coasts.

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