Sadejakson

Sadejakson is a meteorological term used to describe a discrete period of rainfall within a weather event. The concept is used in Estonian-language climatology and regional forecasting to separate rainfall into individual episodes for analysis, forecasting, and hydrological modeling. A sadejakson begins when measurable precipitation exceeds a defined threshold and ends when rainfall falls below a negligible level for a defined dry interval.

Etymology and usage: The word combines sade (rain) with jakson (a period or phase), forming a compound that means a rain period. In practice, different meteorological agencies may adopt slightly different thresholds and dry-interval definitions, so the exact boundaries of a sadejakson can vary by region or dataset.

Characteristics and criteria: A sadejakson is characterized by its duration, intensity, and spatial extent. It typically starts with a sustained period of rainfall and ends when the precipitation rate drops below a set threshold for a prescribed dry interval. In climate records, a single day or storm system can contain multiple sadejaksons, separated by interludes of little or no precipitation. Data sources include rain gauges, radar observations, and numerical weather models.

Applications: The concept helps hydrologists and forecasters analyze rainfall patterns, estimate river and urban drainage responses, and improve event-based climate statistics. By partitioning rain into episodes, researchers can compare storm behavior across seasons, locations, and decades while maintaining a consistent framework for rainfall characterization.

See also: Precipitation event, Rainfall intensity, Hydrological modeling, Climatology.