Dynamics of meteorological time series on the base of ground measurements and retrospective data from MERRA‐2 for Poland

A comparison study has been performed to assess the dynamics of meteorological processes in Poland on the basis of meteorological time series of air pressure, air temperature and wind speed coming from 35 synoptic stations belonging to the Institute of Meteorology and Water Management—National Research Institute (IMGW‐PIB) and from the nearest grid points of the Modern‐Era Retrospective Analysis for Research and Applications, Version 2 (MERRA‐2) produced at NASA's Global Modelling and Assimilation Office from January 1, 2007 to October 31, 2016. Apart from comparative statistics, the differences in the multifractal properties of the time series were evaluated with the use of MultiFractal Detrended Fluctuation Analysis (MFDFA), both for hourly and daily data, showing a high degree of similarity between the MERRA‐2 and IMGW‐PIB series. For the air pressure and air temperature, not only were high determination coefficients (close to .99) between the time series coming from the two sources noticed, but there were also similarities with the MFDFA parameters. Lower correlations between the time series of the wind speed obtained from the two studied databases were observed, which was related to differences in the data structure and methodology of the measurements for specific IMGW‐PIB stations. Additionally, to verify data similarities coming from the IMGW‐PIB and MERRA‐2 databases, the correlations between specific multifractal parameters and the orography were estimated and compared. For the air pressure and temperature, a remarkably high correlation was found between the multifractal parameter α0 and the height above sea level of the measurement site. An analysis of the source of multifractality was performed, indicating that, for all studied meteorological elements and both data sources, the long‐range correlations prevail. A comparison has been performed for Poland using meteorological time series from 35 synoptic stations of the Institute of Meteorology and Water Management (IMGW‐PIB) and the nearest grid points of the Modern‐Era Retrospective Analysis for Research and Applications (MERRA‐2). High similarity of time series coming from those two data sources confirmed by statistical and multifractal analyses suggest that MERRA‐2 data can be very useful for analyses of the climate dynamics change and can be used interchangeably with the ground data.