Variables

In some tests, such as SCT and FGT, two ranges of values have to be defined around each observation. The ranges of admissible and valid values (see ...).

Temperature (variable=T)

• Range of admissible values is observed value ± 20 °C
• Range of valid values is observed value ± 1 °C

Precipitation (variable=RR)

• General constraints
  • lower value have to be greater or equal to 0 mm
• Range of admissible values has:
  • lower value is the minimum value between (observed value - 10 mm) or (observed value - 0.5 * observed value)
  • higher value is the maximum value between (observed value + 10 mm) or (observed value + 0.5 * observed value)
• Range of valid values has:
  • lower value is the minimum value between (observed value - 1 mm) or (observed value - 0.1 * observed value)
  • higher value is the maximum value between (observed value + 1 mm) or (observed value + 0.1 * observed value)

Precipitation correction for wind-induced undercatch

The in-situ observed precipitation is adjusted for the wind-induced undercatch as described by Wolff et al. (2015).

The information required to apply this correction are: the two-meter air temperature and the ten-meter wind speed, which in TITAN are derived from gridded fields provided by the user. The temperature is adjusted for elevation differences between the station elevation and the gridded temperature field.

Reference:

• Wolff MA, Isaksen K, Petersen-Øverleir A, Ødemark K, Reitan T, Brækkan R. Derivation of a new continuous adjustment function for correcting wind-induced loss of solid precipitation: results of a Norwegian field study . Hydrology and Earth System Sciences. 2015 Feb 1;19(2):951.