snow_estimated_counts#

hydrometlib.cosmos.snow_estimated_counts(cts_smo, snow, time)[source]#

Calculate CRNS count estimates when there is snow [counts h-1]

This derivation reconstructs CRNS counts as if there had been no snow, because snow suppresses the counts. During a snow event, the estimated count is set to the value of the counts just before the snow started. If the counts increase, so should the estimate.

\[\begin{split}\hat{C}_t = \begin{cases} C_t & \text{if } C_t > \hat{C}^{\,init} \\ \hat{C}^{\,init} & \text{otherwise} \end{cases}\end{split}\]

where \(\hat{C}^{\,init}\) is the smoothed count at the start of the current snow period, carried forward. \(\hat{C}_t\) is null outside snow periods. Snow periods are identified from snow using 24- and 48-hour offsets (see the source for the event-detection logic).

Reference: Wallbank JR, Cole SJ, Moore RJ, Anderson SR, Mellor EJ.

Estimating snow water equivalent using cosmic-ray neutron sensors from the COSMOS-UK network. Hydrological Processes. 2021;35:e14048. https://doi.org/10.1002/hyp.14048

Parameters:

  • cts_smo (Expr) – Smoothed neutron counts, already corrected for influences on cosmic-ray intensity [counts h-1]

  • snow (Expr) – Boolean values indicating if snow is present on that day [unitless]

  • time (Expr) – Hourly timestamps corresponding to cts_smo values [datetime]

Return type:

Expr

Returns:

Expression or Series for estimated counts during snow periods [counts h-1]. Null when not in a snow period.

Note

Order-dependent: rows must be sorted by time on a regular hourly grid, as the calculation shifts by 24- and 48-hour offsets.