Antecedent precipitation index
From AMS Glossary
(Redirected from Api)
antecedent precipitation index
(Abbreviated API.) A weighted summation of daily precipitation amounts, used as an index of soil moisture.
The weight given each day's precipitation is usually assumed to be an exponential or reciprocal function of time with the most recent precipitation receiving the greatest weight. The antecedent precipitation index method is commonly used to initialize some rainfall models.