Closed‐form approximations to the error and complementary error functions and their applications in atmospheric science

The error function, as well as related functions, occurs in theoretical aspects of many parts of atmospheric science. This note presents a closed‐form approximation for the error, complementary error, and scaled complementary error functions, with maximum relative errors within 0.8%. Unlike other approximate solutions, this single equation gives answers within the stated accuracy for real variable x ∈ [0∞). The approximation is very useful in solving atmospheric science problems by providing analytical solutions. Examples of the utility of the approximation are: the computation of cirrus cloud physics inside a general circulation model, the cumulative distribution functions of normal and log‐normal distributions, and the recurrence period for risk assessment.