c. Changes in the Equilibrium State (Circulation Pattern)
A summary of the changes in atmospheric structure with increasing solar constant will be given below. We will first present cases in which the equilibrium states haves been reached.
Figure 1 provides an overview of the thermal and circulation structures of the atmosphere. This figure shows the meridional temperature distributions and mass stream functions for cases in which equilibrium states have been reached. The following observations may be made based on the figure.
- Temperature increases globally with the increase of solar constant.
The increase of the value of temperature is brought about by an increase of value of optical depth that results from an increase in water vapor content. (See Specific humidity distribution and Relative humidity distribution for information on water vapor distribution.) The increase in water vapor content also causes the total air mass to rise gradually. (For detailed descriptions on these changes, see Global Mean Values in the Equilibrium State.)
- There is no change in the basic pattern of atmospheric circulation even when solar constant increases.
The Hadley cell in the low latitudes and the indirect circulation in the high latitudes are present for all cases. However, note that the depth of the Hadley cell increases with an increase in the solar constant. In response to such changes, an upward shifting in the position of the tropopause and the subtropical jets is observed. For a more detailed description of these features, see Temperature distribution and mass stream function (troposphere), Temperature distribution and mass stream function (upper layer), Condensation heating distribution, Zonal wind distribution (troposphere), and Zonal wind distribution (upper layer).
Figure 1: The meridional temperature distributions (K) and mass stream functions (kg/sec) in the cases of experiments S1200, S1380, S1500, S1550, and S1570.
Figures referred in this section are included in Appendix E and listed as follows:
- Global Mean Values
- Temperature Distribution and Mass Stream Function (Troposphere)
- Condensation Heating Distribution (Troposphere)
- Specific Humidity Distribution (Troposphere)
- Relative Humidity Distribution (Troposphere)
- Zonal Wind Distribution (Troposphere)
- Temperature Distribution and Mass Stream Function (Upper Layer)
- Zonal Wind Distribution (Upper Layer)