In this study downward longwave (LW) atmospheric radiation data for the period of 2014–2020 were used to search for short-term periodicities using fast Fourier transform (FFT). Several local peaks in the power spectrum density were found and established. The time series exhibits a series of significant peaks (exceeding the 95% confidence limit), such as at 273 days, 227 days, 200 days, 178 days, 157 days, 110 days, 120 days, 87 days, 73 days, 53–56 days, 35–30 days, 25–27 days, 21 days, 13 days, and 9–10 days.

Moreover, cosmic ray data from KACST muon detector and the Oulu neutron monitor, as well as the data for the solar radio flux at 10.7 cm (F10.7 cm), Dst index, and solar wind speed for the same period as the LW data, were used to look for common cyclic variations and periodicities matching those found in the LW radiation. This was done to investigate the possible effect of the solar activity parameters on LW radiation. Several common periodicities were observed in the spectra of all the variables considered, such as 227 days, 154–157 days, 25–27 days, and 21 days. Some of the periodicities found in the LW radiation spectrum can be attributed to the modulation of the cosmic ray intensity by solar activity. Others are attributed to the disturbances in the interplanetary magnetic field. Based on the spectral results, we suggest that the solar signals may directly or indirectly affect the variations of the downward longwave radiation, which in turn may affect climate change.

在这项研究中，使用2014-2020年期间的向下长波（LW）大气辐射数据，使用快速傅里叶变换（FFT）搜索短期周期。发现并建立了功率谱密度中的几个局部峰。时间序列显示出一系列显着的峰值（超过95％的置信度上限），例如273天，227天，200天，178天，157天，110天，120天，87天，73天，53– 56天，35-30天，25-27天，21天，13天和9-10天。

此外，来自KACST介子探测器和Oulu中子监测器的宇宙射线数据，以及与LW数据在同一时期内的10.7 cm（F10.7 cm）太阳辐射通量，Dst指数和太阳风速的数据用来寻找与LW辐射中发现的常见周期性变化和周期性匹配的周期性。这样做是为了研究太阳活动参数对长波辐射的可能影响。在所有考虑的变量的光谱中观察到几个共同的周期性，例如227天，154-157天，25-27天和21天。在LW辐射光谱中发现的某些周期性可以归因于太阳活动对宇宙射线强度的调制。其他归因于行星际磁场的干扰。根据光谱结果，