A 15-year record of seasonal variation in the isotopic composition of precipitation water over continental Portugal

The Nuclear and Technological Institute (Instituto Tecnológico e Nuclear—ITN) in cooperation with the International Atomic Energy Agency (IAEA) has been conducting a nationwide survey of hydrogen (²H/¹H) and oxygen (¹⁸O/¹⁶O) isotopic composition of monthly precipitation since 1988. This paper focuses on basic features of spatial and temporal distribution of δ¹⁸O and δ²H in the precipitation over Continental Portugal derived from ITN database. Phenomenological relationships between stable isotopes composition of precipitation and various climate-related parameters (local air temperature, distance to the Atlantic coast, altitude, amount of precipitation) are established and discussed.