Estimating Soil Heat Flux in Jordan Based on ERA5 Parameters and NCEP/NCAR Energy Outputs: Definite Radiative Forcing of Climate Change Using PCA

Internal variability changes in soil surface temperature and reflective radiation drove climate to change and vice versa over all time scales. This study investigates the heat flux components and the climate variables that drive the change in surface soil temperature down to 15.0 cm. We analyze the correlations of energy and radiation components to climate variables by coding principle component analysis (PCA) and finding the radiative forcing of atmosphere-energy-climate-soil continuum systems using datasets derived from ERA5 and NCEP/NCAR projections. The vectors contributing to the continuum were the shortwave, net solar radiation, and sensible flux are the main drivers. The average 72-year shortwave in the study locations was - 190.63 W/m(2). Because of the upwelling radiation to the atmosphere, the longwave flux did not exceed the shortwave over the study's location. The sensible heat flux was the lowest in the northwestern highlands (approximately 32 Watt/m(2)) and the highest range during summer was 150-180 Watt/m(2) over the country. This variability in net radiation partitioning led to changes in surface warming and the responding climate. This study found that the average monthly soil surface temperature bound was 10-20 degrees C from November to March at all locations except for Amman and Ruwaished. The calculated soil heat storage is positive all year in the Dead Sea with an annual average of 76.53 W/m(2). The lowest storage heat was in Amman with an annual average of - 44.42 W/m(2). The anomalies of annual ERA5 reanalysis of main climate contributors extended from (- 5.46 to + 5.53 degrees C), (- 5.66 to + 4.36 degrees C), (- 1.3 to 2.87 mm/day), and around (- 25.97% to a maximum of 20.99%) for maximum and minimum near-surface air temperatures, daily precipitation, and relative humidity, respectively. The long-term mean evaporation was very low approximately - 1.85 x 10-7 mm. Mean monthly wind speed illustrates low-frequency variability by - 0.06 m/s. PCA represented the correlation coefficients of the climate variables that affected soil temperature the most: near-surface air temperature, maximum, and minimum (> 0.95). Soil-water content, precipitation, and humidity played a secondary negative role to a certain extent by regulating and slowing down the soil heat transfer - 61, - 64, and - 91%, respectively. This study enhances the understanding of energy partitioning and incorporates satellite products and climate simulations to recognize key influencing factors of energy changes and climate footprints toward soil heat flux that affect the biosphere, humans, and energy use.