Validation of HIROMB during 1995-96

IROMB (High Resolution Operational Model of the Baltic Sea) is the result of a combined effort between BSH (Bundesamt för Seeschiffahrt und Hydrographie) and SMHI (Swedish Meteorological and Hydrological Institute). In its present form, the model is a modified version of the BSH operational model (Kleine, 1994) with identical boundaries to the North Atlantic. The cooperation started in summer 1994 when the model was set up at SMHI. The first operational runs started in the sumrner 1995 and since then the model has been running daily except fora limited number of periods when there were no meteorological input from the HIRLAM (atmospheric) model available because of computer problems. During the first months, some occasions with stability problems occurred, leading toa restart from the climatological fields. This report presents results from a continous verification exercise, where model results are compared to observations of water level, surface temperature, currents, ice thickness and salinity and temperature profiles. The times series data are taken from the period September-November 1996 while the ice thickness data are from November and December 1996 and the sea surface temperature data are taken from August, November and December 1996. For a detailed description of the model, the reader is referred to a forthcoming report by Funkquist and Kleine

Validation of HIROMB during 1995-96

IROMB (High Resolution Operational Model of the Baltic Sea) is the result of a combined effort between BSH (Bundesamt för Seeschiffahrt und Hydrographie) and SMHI (Swedish Meteorological and Hydrological Institute). In its present form, the model is a modified version of the BSH operational model (Kleine, 1994) with identical boundaries to the North Atlantic. The cooperation started in summer 1994 when the model was set up at SMHI. The first operational runs started in the sumrner 1995 and since then the model has been running daily except fora limited number of periods when there were no meteorological input from the HIRLAM (atmospheric) model available because of computer problems. During the first months, some occasions with stability problems occurred, leading toa restart from the climatological fields. This report presents results from a continous verification exercise, where model results are compared to observations of water level, surface temperature, currents, ice thickness and salinity and temperature profiles. The times series data are taken from the period September-November 1996 while the ice thickness data are from November and December 1996 and the sea surface temperature data are taken from August, November and December 1996. For a detailed description of the model, the reader is referred to a forthcoming report by Funkquist and Kleine

Parameterization of lake thermodynamics in a high-resolution weather forecasting model

A model for the parameterization of lake temperatures and lake ice thicknesses in atmospheric models is presented. The model is verified independently, and it is also tested within the framework of the High Resolution Limited Area Model(HIRLAM), applied operationally for short range weather forecasting at the Swedish Meteorological and Hydrological Institute (SMHI). The lake model is a slab model based upon energy conservation and treats the lakes as well mixed boxes with depths represented by the mean depths. The model is forced by near surface fluxes calculated from total cloudiness, air temperature, air humidity and low-level winds. A data base, describing 92000 Swedish lakes. provides the model with lake mean depths, areal sizes and locations. When the model is used for parameterization of lake effects in the atmospheric model, all the smaller lakes and the fractions of larger lakes within each horizontal grid square of the atmospheric model are parameterized by four model lakes, representing the lake size distribution. The verification of the lake model is done by comparing it with a more advanced, vertically resolved model, including parameterization of turbulent mixing processes, as well as by comparison with observations. A sensitivity test shows great interannual variations of the ice-covered season, which implies that lake models should be used instead of climate data. The results from an experiment with two-way coupling of the lake model to the atmospheric model are verified by comparing forecasted weather parameters with routine meteorological observations. These results show that the impact of lake effects can reach several degrees C in air temperatures close to the surface

Nemo-Nordic 2.0 : operational marine forecast model for the Baltic Sea

This paper describes Nemo-Nordic 2.0, an operational marine model for the Baltic Sea. The model is used for both near-real-time forecasts and hindcast purposes. It provides estimates of sea surface height, water temperature, salinity, and velocity, as well as sea ice concentration and thickness. The model is based on the NEMO (Nucleus for European Modelling of the Ocean) circulation model and the previous Nemo-Nordic 1.0 configuration by Hordoir et al. (2019). The most notable updates include the switch from NEMO version 3.6 to 4.0, updated model bathymetry, and revised bottom friction formulation. The model domain covers the Baltic Sea and the North Sea with approximately 1 nmi resolution. Vertical grid resolution has been increased from 3 to 1 m in the surface layer. In addition, the numerical solver configuration has been revised to reduce artificial mixing to improve the representation of inflow events. Sea ice is modeled with the SI3 model instead of LIM3. The model is validated against sea level, water temperature, and salinity observations, as well as Baltic Sea ice chart data for a 2-year hindcast simulation (October 2014 to September 2016). Sea level root mean square deviation (RMSD) is typically within 10 cm throughout the Baltic basin. Seasonal sea surface temperature variation is well captured, although the model exhibits a negative bias of approximately −0.5 ∘C. Salinity RMSD is typically below 1.5 g kg−1. The model captures the 2014 major Baltic inflow event and its propagation to the Gotland Deep. The model assessment demonstrates that Nemo-Nordic 2.0 can reproduce the hydrographic features of the Baltic Sea.</p