Spatial and temporal variation in weather events critical for boreal agriculture: II Precipitation

Abstract

There is great temporal and spatial variation in precipitation in Finland. Both drought episodes and repeated, abundant rains may interfere with crop growth, yield and quality formation, and many agricultural operations (such as tillage, sowing, crop protection and harvesting). The windows for optimal operations are often narrow due to the short growing season and variable weather conditions. Field traffic at high soil moisture may e.g. cause soil compaction. Also, the high environmental footprint on agriculture under high latitude conditions is often attributable to fluctuations in precipitation. The station-wise precipitation observations from the Finnish Meteorological Institute for the time period of 54 years (1961‒2014) were interpolated to a regular 10 km × 10 km grid covering the whole country. Several successive time slices were used to calculate the likelihood of: 1) drought periods and 2) periods with repeated rains with above normal precipitation sum so that both of these lasted for at least a) two weeks or b) three weeks. We demonstrated substantial spatial and temporal variation in the likelihood of drought and repeated rains: drought episodes were common during the early half of the growing season, while again repeated rains with high accumulated precipitation (lasting for two weeks) became common in the latter part of the growing season. Though, we highlighted in this paper some examples of how these events may affect agriculture and their environmental impacts, the datasets published here may be applied for many other assessments.

Keywords

• crop
• drought
• growing season
• heavy rains
• probability
• spatial variation