Global warming scenarios from CO2 increases are envisioned to bring about rainfall enhancement and resulting upper tropospheric water vapor rise. This initial water vapor enhancement has been hypothesized and programmed in climate models to develop yet additional rainfall and water vapor increase. This causes an extra blockage of IR energy to space (a positive feedback warming mechanism). This additional rainfall and IR blockage is modeled to be approximately twice as large as the additional rainfall needed to balance the increased CO2 by itself. The reality of this additional warming and extra IR blockage has been questioned by many of us. This study analyzes a wide variety of infrared (IR) radiation differences which are associated with rainfall differences on different space and time scales. Our goal is to determine the extent to which the positive rainfall feedbacks as are included in the climate model simulations are realistic.
We have analyzed 21 years (1984-2004) of ISCCP (International Satellite Cloud Climatology Project) outgoing solar (albedo) and outgoing longwave infrared (IR) radiation (often referred to as OLR) on various distance (local to global) and time scales (1 day to decadal). We have investigated how radiation measurements change with variations in precipitation as determined from NCEP-NCAR Reanalysis data on a wide variety of space and time scales (Figure 1). We have stratified our radiation and rainfall data into three latitudinal sections and six distinctive longitudinal areas (Figure 2). Infrared and albedo changes associated with rainfall variations by month (January to December) and by yearly periods for the globe (70oN-70oS; 0-360o) as a whole and separately for the tropics (30oN-30oS; 0-360o) have been studied. This analysis shows they are not realistic.
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from William M. Gray and Barry Schwartz