Reference evapotranspiration during the growing season in Poland (central Europe) in response to ongoing climate changes (1966–2020)

Abstract Evapotranspiration is an important part of the water cycle and influences, for example, management agricultural production. The article presents temporal spatial changes in reference evapotranspiration ( ET o ) growing season (April–September) against background climatic conditions Poland years 1966–2020. was calculated using Penman–Monteith method data from 37 meteorological stations network Institute Meteorology Water Management‐National Research Institute. For April–September, average sum 529 mm. In terms distribution, values were lowest northern (Kołobrzeg, 480 mm; Lębork, 488 mm) highest central lowlands (Warsaw, 570 Poznań, 566 mm). individual months, ranged 53 to 63 mm April September 108–112 June July. Poland, 1966–2020, showed a statistically significant upward trend 16.4 mm/10 year. This result of, inter alia, increases sunshine duration air temperature decrease relative humidity (respectively: 62 h/10 year, 0.40°C/10 year −1%/10 year) during Poland. Within multiyear study period, maximum occurred 2018, reaching >700 At that time, under influence very intense anticyclonic circulation. confirmed by relationship between circulation index which 55 years.