Abstract:

Any solar system planet or satellite with a thick atmosphere shows a positive Greenhouse Effect (GE) according to NASA. The average planetary surface temperature and the average longwave radiation flux seen from space has both been measured extensively. This information provides a basis to calculate the planetary (global) GE. Hence, the NASA planetary GE values for Venus, Earth, Mars and Titan are 510, 34, 0 and 10 degrees Kelvin (NASA 2016). It can and should be questioned why the GE differs so much on different planets. A way to come closer to an answer is to calculate a number of regional GEs (RGE) on earth and study their variations.
This is possible since the outgoing longwave radiation (OLR) has been measured carefully during many years by several space crafts. It is possible to calculate an average emission temperature for any specific region on earth. Gridded monthly data of both OLR and surface temperature for selected regions averaged over many years were provided by www.cdc.noaa.gov (2009), data which have been used in this study. It turns out that the RGE values on earth varies between about minus 10 to plus 52 Kelvin depending on a number of physical factors. The RGE value was highest in Amazonas and lowest at the South Pole. The RGE values were above the average of 34K over the oceans and in equatorial regions strongly suggesting an impact of water vapor concentration as an important factor. Which physical mechanism that probably is dominating the GE value on earth and any planet with a dense atmosphere is discussed.















