9302954 Otlmans The "thermostat hypothesis" depends upon three postulates. First, a super-greenhouse effects exists. Satellite data reveal that the atmosphere over the warmest oceans is very humid, causing it to trap a significant fraction of the infrared energy emitted by the ocean. Furthermore, the infrared trapping - known as the greenhouse effect - increases very sharply with increasing SST in regions of convection. This creates an instability which requires some sort of negative feedback (e.g. thermostat) in order to keep the ocean and atmosphere in their present, stable state. Second, there is a threshold temperature above which reach altitudes of 16 km (55,000 ft.) and extend over tens o thousands of square kilometers, reflect significant amounts of solar energy back to space so that the sea surface cools down, hence, the thermostat. The goal of CEPEX is to test the thermostat hypothesis and thus understand the role of the water vapor greenhouse effect, cloud-radiative interactions and evaporation in regulating SSTs. Three aircraft will be deployed in CEPEX: A high altitude aircraft - flying above the anvil clouds at altitudes of 55,000 - 60,000 feet - to collect data on solar energy reflected by clouds, infrared energy radiated by the surface-atmosphere system, and the top and bottom altitudes of the cirrus anvils; an intermediate aircraft - flying below the anvils at 35,000 - 40,000 feet - to measure the super-greenhouse effect, the energy regulation by anvil clouds, and the vertical distributions of water vapor and temperature; and a low altitude aircraft to measure the evaporation and heat release from the ocean to the atmosphere from an altitude of about 150 feet. Since the central objective is to measure the impact of SST differences, flights tracts will span the central equatorial Pacific, about 700 nautical miles to either side of the data line. This region encompasses the desired SST range, with frequent convection west and south of the date line, but little to the east. The flights measuring radiant energy will originate from FIJI island (17oS, 178oE). The region between Fiji and the equator also contains large SST gradients in the desired range between 27oC and 30oC. Evaporation measurements will be made along the equator between Nauru Island and Christmas Island. The high altitude measurements will be made over a one month period beginning approximately March 1, 1993. The high and intermediate aircraft will fly about every other day for a total of 100 flight hours each. Surface evaporation measurements will be taken by the low-level aircraft during the first half of the experiment. The question of how tropical SSTs are regulated is important to understanding the regulation of the Earth's climate in general:in particular, the atmospheric behavior in the warm pool region may become more widespread in the event of anticipated global warming.***
