The results of measurements of the long-wave radiation at the Fonovaya observatory

One of the climate-forming factors is the radiation balance of the underlying surface. Monitoring the components of the radiation balance of the earth's surface is important to analyze climate change.

Employees of the V.E. Zuev Institute of Atmospheric Optics SB RAS conduct long-term continuous monitoring of the total, surface-reflected short-wave radiation (λ = 0.3–2,800 µm), as well as the outgoing long-wave radiation and incoming long-wave radiation of the atmosphere (λ = 4.5–42,000 µm) at the Fonovaya observatory (56⁰25´ N, 84⁰04´ E). Measurements of long-wave radiation are carried out using a CNR4 radiometer manufactured by Kipp&Zonen since November 2020 [1]. CNR4 radiometer were installed at a height of 1.5 m and connected in differential mode to the multifunction I/O device.

In this report, the results of measuring the long-wave components of the radiation balance (incoming long-wave radiation of the atmosphere E_i and the outgoing long-wave radiation E_o) in the background region of Western Siberia for the period 2021-2024 are presented.

The annual variation of E_i and E_o is obtained. Analysis of the monthly amounts of E_i and E_o showed that in their annual calculation the maximum amount is added in the summer (July–August) and minimum in the winter (January–February) months. The ratio of monthly amounts E_o / E_i during the year ranged from 1.08 to 1.22.

For each month, extreme average hourly values and hourly sums E_i and E_o are determined.

The daily cycle of E_i and E_o for each month is considered. The amplitude of the daily cycle varies throughout the year. The amplitude of the daily cycle E_o is significant in the summer months (DE_o = 50÷70 W/m²), in winter it is smaller (E_o = 7÷12 W/m²). E_o has a pronounced daily cycle with a maximum at 12–15 o'clock. For E_i, the daily cycle is weakly expressed.

The calculation of changes in the long-wave radiation balance B_l and incoming radiation from the cloudiness grade was carried out. In the cold period with overcast skies (10/10 points), negative air and soil temperatures, and snow cover, the daily variation of B_l is weakly expressed. The daily amplitude is 5 W/m² (10/10 points), 22 W/m² (clear). The daily amplitude of B_l varies in the range from 30 W/m² (10/10 points) to 70 W/m² (clear) in the absence of snow cover. Incoming long-wave radiation increases by 40 –70 W/m² for overcast skies (10/10 points).

The research was carried out as part of the most important innovative project of national importance « Russian climate monitoring system».

Belan B. D., Ivlev G. A., Kozlov A. V., Pestunov D. A., Sklyadneva T. K., Fofonov A. V. Solar Radiation Measurements at the Fonovaya Observatory: Part I: Methodical Aspects and Specifications // Atmospheric and Oceanic Optics. 2023. V. 36. No. 1. P. 47–53. DOI: 10.1134/S1024856023020045.