Homogenization of specialized meteorological data sets

Abstract

 Сlimate change assessments should be based on homogeneous data

sets of hydrometeorological characteristics, meaning that changes in these data sets should occur solely due to weather changes. Data from hydrometeorological stations does not always meet these requirements, as instrument readings are sometimes influenced by factors other than weather conditions.

The All-Russian Research Institute of Hydrometeorological Information - World Data Сenter (VNIIGMI-MDС) provides users with a specialized meteorological data set for over 500 stations in the Russian Federation. This study utilizes five data sets from this data set: average, maXimum, and minimum air temperature, precipitation, and relative humidity.

Following a comparative evaluation of the methods for obtaining homogeneous meteorological data sets proposed by the WMO and the climatic and geographical conditions of the Russian Federation, the RHtests software package was selected to fulfill the research objectives. Homogenization of the data yielded homogeneous series of the specified atmospheric characteristics over a long observation period, and an assessment of data series homogeneity violations was made at each meteorological station. The period from 1947 to 2016 can be considered the most suitable for assessing climate change in the Russian Federation, as stations relatively evenly distributed across the country had available observation data for this time interval. Based on these data, digital maps of the Russian Federation's territory were modeled using homogeneous and heterogeneous meteorological values.

Фундаментальная и прикладная климатология, т. 12, № 2, 2026

Fundamental and Applied Climatology, v. 12, no. 2, 2026

A comparison of the maps' statistical characteristics revealed that, for the studied period, the linear trend coefficient for annual air temperature based on homogeneous data is lower (+2.4°С/100 years) than based on heterogeneous data (+2.8°С/100 years). The absolute maXimum temperature increased by +0.27°С; the amplitude between the maXimum and minimum temperatures also increased by

+0.58°С. Precipitation, according to station data, has increased by an average of 92 mm per 100 years, which is less than the value reported by the heterogeneous data (122 mm/100 years). Relative humidity data were analyzed for the period from 1966 to 2023. According to the heterogeneous data, relative humidity increased until the middle of the specified period, both seasonally and on average for the year. Relative humidity, according to the homogeneous data, has tended to decrease from 1966 to 2023, especially in spring and summer, while it remained virtually unchanged in autumn and winter.

The studies showed that when working with data obtained from the hydrometeorological network, homogenization is necessary to obtain homogeneous data series, as many non-meteorological factors distort the measurement results. WMO-recommended methods should be used to obtain homogeneous climate series that can be used in further research.