LATITUDINAL FEATURES OF TROPOSPHERIC RESPONSE TO 27-DAY CYCLIC VARIATIONS OF SOLAR ACTIVITY

• Published in: Radio physics and radio astronomy (Print) Vol. 29; no. 4; pp. 293 - 307
• Main Authors: Zakharov, I., Chernogor, L.
• Format: Journal Article
• Language: English
• Published: National Academy of Sciences of Ukraine, Institute of Radio Astronomy 01.12.2024
• Subjects: 27-day cycle; solar activity; stratosphere-troposphere interactions
• ISSN: 1027-9636; 2415-7007
• DOI: 10.15407/rpra29.04.293

Subject and Purpose. The troposphere is a natural channel for the propagation of meter- and shorter wavelength radio waves. Studying the impact of solar activity (SA) on the condition of the troposphere is important for improving the accuracy of weather forecasts and understanding the state of the tropospheric radio channel. The present paper has been aimed at identifying and comprehending the solar-tropospheric interactions resulting from the 27-day cycles of solar activity. Methods and Methodology.The study was conducted through twenty 27-day cycles of solar activity, over an interval of latitudes between 0 and 80°N, and at four east longitudes, specifically 30, 180, 240 and 330°E. The atmospheric data used were quoted from the NOAA Physical Sciences Laboratory list (https://psl.noaa.gov /data/timeseries/daily/) and concerned sea level pressure, temperature in the troposphere at the height level with a 1000 hPa pressure, stratospheric temperature at the height corresponding to 50 hPa, and zonal wind speed. Results. Reliable estimates have been obtained for the atmospheric parameters varying over 27-day cycles, that revealed maximum amplitudes at middle and high latitudes,: in particular the sea level pressure up to 12 hPa, temperature in the troposphere up to 5.3 K, and up to 3.5 K in the stratosphere . The relative amplitudes (about 1.3%) of these variations correlate with the 27-day changes in the solar UV radiation of a 205 nm wavelength. Anti-phase changes have been observed between the troposphere and stratosphere temperatures over the continents in the Western and Eastern hemispheres, as well as anti-phase changes in pressure over the continents and the oceans. The change in the sign of temperature variation with height occurs near the tropopause, being accompanied by a ~ 1 km change in the tropopause height. At the latitude of 60°N, the 27-day changes in the zonal wind speed in the stratosphere may reach tens per cent. A persistent solar effect is observable not in winter time alone, but in summer as well, while of a smaller amplitude. Conclusions. Owing to stratosphere-troposphere interaction effects, the troposphere demonstrates a high sensitivity to 27-day variations of the solar UV radiation. The main properties of the 27-day variations of atmospheric parameters testify to the important role of planetary and meteorological- scale Rossby waves in the realization of solar influence.