Decomposition of the Latitudinal Variation in the Long-Term Average Temperature in the Northern Hemisphere in 1897–2010 Based on Measurements at Weather Stations and Data on Astronomical Insolation

Air temperature data at weather stations in the Northern Hemisphere and astronomical insolation data were ordered by increasing latitude and analyzed together for different samples between 1897 and 2010. Using a step-by-step regression of the latitudinal variation in the long-term average temperature to a polynomial of astronomical insolation, a latitudinal trend in the temperature determined by the Sun and fluctuating regression residuals, which characterize individual features of data, are identified. The absence of interaction of these components is numerically achieved for any samples. It has been found that the latitudinal trend in the long-term average temperature completely determines the warming and contributes about 82% to the total temperature dispersion in the Northern Hemisphere for available samples. The boundaries of regions where temperatures are above and below the latitudinal trend in the long-term average temperatures reveal known geographic structures, thus verifying the trend.