OHD/HL/HSEB - MODS

Precipitation Mods

DHM precipitation Modifiations (PMODS) are a way for users to edit the hourly accumulated observed precipitation in each grid cell. Precip_mods are never applied to future precipitation. Precip_mods contain the following information

.DPRECIP 1201200612z 1202200612z 1205200612z 2.0

Has the mod expired?

DHM determines if the precip mod has expired by comparing the mod's valid date and time (i.e. when the mod was created) to the model run's date and time;
For example if the model is run at 12/02/2006 12z, then following should be true

Expired Mods

When a precip mod has expired, the mod's end date and time may automatically change to the valid date and time. For example if a precip mod with a valid date and time of 12/02/2006 12z has expired, then the following should be true:

When to Apply Mods

PMODS are only for model time steps within the mod's start and end date window.
For example, if the model is run for the period 12/02/2006 to 12/07/2006. Then the folowing should be true

Rules for Modifying Values

A valid Precip_Mod lowers/increases the observed hourly accumulated precipitation in each cell by multiplying the mod value and the original cell value

Valid Precipitation Mods

Valid precip mods have a mod start date and time must be before the mod end date and time

Valid precip mods have values greater than or equal to zero

Multiple Precipitation Mods

Multiple PMODS is also supported. Any overlapping periods result in a cumulative effect. For example, if the following mods are defined, the following should be true.

.DPRECIP 1201200312z 1203200312z 1205200312z 2.0 .DPRECIP 1202200312z 1204200312z 1205200312z 2.0