PTHBV. Gridded daily values of temperature and precipitation over Sweden since 1961

PTHBV is a climate database that has been built up with a special focus for hydrological model calculations. The database contains daily values for precipitation and temperature, which are mainly used as inputs for calculations with hydrological models, such as the S-Hype and HBV models. Climate data from 1961 onwards is stored in PTHBV in a nationwide grid with a resolution of 4x4 km. PTHBV is an abbreviation for Precipitation Temperature Hydrological Agency Water Model. Data from SMHI’s meteorological stations have been interpolated to the database grids using a geostatistic interpolation method called optimal interpolation. The method involves, among other things, taking into account both the stations’ distances from the calculation box and their correlation. To describe the spatial variation, information about topography, typical wind direction and wind power is used in different parts of the country. In the database, the observed precipitation has also been corrected for measurement losses, mainly caused by some of the precipitation blowing past the precipitation meter. The measurement losses have been calculated using methods specified by Alexandersson (2003). These methods take into account how wind exposed the measuring station is and whether precipitation falls like snow or rain, which is determined by the temperature. The PTHBV database is mainly based on observations from the Swedish meteorological stations that are part of SMHI’s station network. In the border regions with Norway, a number of stations are also used in the Meteorological Institute’s station network in Norway. Once a year, in April, a review of changes in the station network is made. Following this review, the database will be updated with the recalculated values for the previous year and for the period January to February of the current year. Closure or relaunching of stations may in some cases cause homogeneity breaks in the database’s time series.