A new technique for estimating D-region effective recombination coefficients under different solar flare conditions

Under solar flare conditions, the intensity of the solar X-rays below 10 Å increases by several orders of magnitude, while the increase in intensity of H-L is small. Photo-ionization rates in the various wavelength bands in theXUV spectrum have been presented graphically as a function of altitude under quiet, M3, X4, and outstanding flare conditions to show the relative importance of solar X-rays below 10 Å in the height range between 50 and 90 km. Presuming the total time constant for recombination of the ions with electrons remains constant at each altitude under different flare conditions, one can obtain the effective recombination coefficient _eff under these conditions with a knowledge of the quiet time recombination coefficient, the production rate profiles and profiles. The importance of the ratio of negative ions to electrons below 70 km in lowering the effective electron loss rates has been highlighted.