6 - 



Where: F(t) is the heat flux as a function of time in cal min _ l cm" 2 



A C02 is the change in atmospheric CO2 from the 1880 



value (293 ppm) in ppm. 

 4 T is the change in atmospheric temperature (surface 



level) from the 1880 value in °C 

 A CH4 is the change in atmospheric CH4 from the 1880 



value (1.6 ppm) in ppm. 

 A N20 is the change in atmospheric N2O from the 1880 



value (.300 ppm) in ppm. 

 A CC3 is the change in CCI3F from the 1880 value 



(0 ppb) in ppb. 

 A CC2 is the change in CC1 2 F 2 from the 1880 value 



(0 ppb) in ppb. 

 4 V is the change in atmospheric optical depth from 



a baseline level due to volcanic activity in dimen- 



sionless units. 

 4 S is the change in solar luminosity from a baseline 



level in fractional units. 

 A T e is the temperature equilibrium sensitivity -- the 



assumed temperature rise when CO2 doubles from the 



1880 level (from 293 to 586 ppm). 



The heat flux is estimated for time periods ranging from 



each month to each year (a semimonthly time step was used in this 



study). The appropriate a T value for calculating F(t) in each 



time period (t=n) is the value estimated for the previous period 



(t=n-l). For a simple one-layer ocean model, a T is obtained by 



solving the following differential equation: 



d A T = F(t) 

 dt C 



Where: C is the heat capacity of the mixed layer of the 



ocean per unit area (cal cm~2). 



Estimates of heat flux from the empirical equation described 



above were compared by Lacis with the RC model calculations. The 



two estimates agreed to within one percent for CO2 values of to 



1220 ppm, and to within 5 percent for CO2 values of 1220 to 



