21 Layer troposphere-stratosphere climate model

The global climate model is extended through the stratosphere by increasing the vertical resolution and raising the rigid model top to the 0.01 mb (75 km) level. The inclusion of a realistic stratosphere is necessary for the investigation of the climate effects of stratospheric perturbations, such as changes of ozone, aerosols or solar ultraviolet irradiance, as well as for studying the effect on the stratosphere of tropospheric climate changes. The observed temperature and wind patterns throughout the troposphere and stratosphere are simulated. In addition to the excess planetary wave amplitude in the upper stratosphere, other model deficiences include the Northern Hemisphere lower stratospheric temperatures being 5 to 10 C too cold in winter at high latitudes and the temperature at 50 to 60 km altitude near the equator are too cold. Methods of correcting these deficiencies are discussed

Climate change and the middle atmosphere, part 1, the doubled CO2 climate.

The impact of doubled atmospheric CO2 on the climate of the middle atmosphere is investigated using the GISS global climate/middle atmosphere model. In the standard experiment, the CO2 concentration is doubled both in the stratosphere and troposphere, and the sea surface temperatures are increased to match those of the doubled CO2 run of the GISS 9 level climate model. Additional experiments are run to determine how the middle atmospheric effects are influenced by tropospheric changes, and to separate the dynamic and radiative influences. These include the use of the greater high latitude/low latitude surface warming ratio generated by the Geophysical Fluid Dynamics Laboratory doubled CO2experiments, doubling the CO2 only in either the troposphere or stratosphere, and allowing the middle atmosphere to react only radiatively.As expected, doubled CO2 produces warmer temperatures in the troposphere, and generally cooler temperatures in the stratosphere. The net result is a decrease of static stability for the atmosphere as a whole. In addition, the 100 mb warming maximizes in the tropics, leading to improved propagation conditions for planetary waves, and increased potential energy in the lower stratosphere. These processes generate increased eddy energy in the middle atmosphere in most seasons. With greater eddy energy comes greater eddy forcing of the mean flow and an increase in the intensity of the residual circulation from the equator to the pole, which tends to warm high latitudes. Increased gravity wave drag in some of the experiments also helps to intensify the circulation. The middle atmosphere dynamical differences are on the order of 10%–20% of the model values for the current climate, and, along with the calculated temperature differences of up to some 10°C, may have a significant impact on the chemistry of the future atmosphere including that of stratospheric ozone, the polar ozone “hole,” and basic atmospheric composition

Climate change and the middle atmosphere, part 1, the doubled CO2 climate.

The impact of doubled atmospheric CO2 on the climate of the middle atmosphere is investigated using the GISS global climate/middle atmosphere model. In the standard experiment, the CO2 concentration is doubled both in the stratosphere and troposphere, and the sea surface temperatures are increased to match those of the doubled CO2 run of the GISS 9 level climate model. Additional experiments are run to determine how the middle atmospheric effects are influenced by tropospheric changes, and to separate the dynamic and radiative influences. These include the use of the greater high latitude/low latitude surface warming ratio generated by the Geophysical Fluid Dynamics Laboratory doubled CO2experiments, doubling the CO2 only in either the troposphere or stratosphere, and allowing the middle atmosphere to react only radiatively.As expected, doubled CO2 produces warmer temperatures in the troposphere, and generally cooler temperatures in the stratosphere. The net result is a decrease of static stability for the atmosphere as a whole. In addition, the 100 mb warming maximizes in the tropics, leading to improved propagation conditions for planetary waves, and increased potential energy in the lower stratosphere. These processes generate increased eddy energy in the middle atmosphere in most seasons. With greater eddy energy comes greater eddy forcing of the mean flow and an increase in the intensity of the residual circulation from the equator to the pole, which tends to warm high latitudes. Increased gravity wave drag in some of the experiments also helps to intensify the circulation. The middle atmosphere dynamical differences are on the order of 10%–20% of the model values for the current climate, and, along with the calculated temperature differences of up to some 10°C, may have a significant impact on the chemistry of the future atmosphere including that of stratospheric ozone, the polar ozone “hole,” and basic atmospheric composition

Regional distribution of transforming growth factor-alpha and epidermal growth factor in normal and portal hypertensive gastric mucosa in humans.

This study was designed to evaluate the concentration and the regional distribution of TGF-alpha and EGF in normal and portal hypertensive human gastric mucosa. To this end we measured by RIA the gastric and duodenal concentration of TGF-alpha and EGF in subjects with chronic hepatitis, who had normal gastric endoscopic appearance, and in patients with liver cirrhosis with and without congestive gastropathy. Our results show that TGF-alpha concentration is significantly higher than EGF concentration in both the stomach and duodenum. No significant regional differences in the distribution of the two peptides were found. Moreover, the gastroduodenal tissue levels of TGF-alpha were comparable in subjects with and without hypertensive gastropathy. EGF gastric concentration was not altered in patients with congestive gastropathy. However, EGF duodenal tissue levels were significantly lower in patients with liver cirrhosis than in noncirrhotic subjects. We speculate that the higher level of TGF-alpha in the gastroduodenal mucosa may support the hypothesis that TGF-alpha and not EGF is the major physiological ligand for TGF-alpha/EGF receptor in the intact gut. Furthermore, the lower duodenal concentration of EGF in cirrhotics might partially explain the increased susceptibility of cirrhotic patients to duodenal ulcer