In this report, an atmospheric model for the calculation of riometer absorption during Polar cap absorption events is given; specifically, an atmospheric response function is calculated and tabulated at necessary altitudes for (1) each month of the year, (2) day and night, and (3) 60 degrees N and 90 degrees N latitude. In addition, a polynomial fit to the atmospheric response function is given in terms of polynomial coefficients. Also tabulated for the conditions above are the collision frequency, atmospheric depth, and scale height.