dagsmeðaltalið

Dagsmeðaltalið is the Icelandic term for the daily mean, the average value of a quantity over a given day. Etymologically, it combines dags meaning day and meðaltal meaning average, reflecting its use as the central tendency of a day’s measurements. In practice, dagsmeðaltalið refers to the daily mean value of a variable such as temperature, humidity, or wind speed.

Calculation typically involves averaging all valid measurements within the 24-hour period. If data are recorded hourly, the daily mean is usually the mean of the 24 hourly values; for irregular sampling, a time-weighted average or interpolation may be employed. When data are incomplete, data-quality rules apply, and imputation or transparent documentation of missing data handling is common. For continuously measured quantities, the daily mean can be defined as the integral of the quantity over the day divided by the day’s length.

Applications of dagsmeðaltalið are widespread in meteorology, climatology, agriculture, energy planning, and environmental monitoring. It is commonly reported alongside other daily statistics, such as the daily maximum (hámark) and daily minimum (lágmark), to characterize diurnal patterns and overall daily conditions.

Limitations include sensitivity to sampling frequency and data gaps; daily means can obscure sub-daily variability or short-term extremes. Consequently, dagsmeðaltalið is best understood in the context of the data collection methods, including observation times, frequency, and quality-control procedures.