Description

The 10-hour timelag fuel moisture \(MC_{10}\) is the moisture content of the 10-hour timelag fuels, which consist of dead roundwood 0.25 to 1 inch in diameter and the layer of litter extending from just below the surface to 0.75 inch below the surface (Deeming et al. 1977).

The calculation of the 10-hour timelag fuel moisture model requires the use of fuel sticks. However, an estimation of the 10-hour fuel moisture at midafternoon without the use of fuel sticks is possible according to the formula described here (Bradshaw et al. 1983).

As for the calculation of the 1-hour timelag fuel moisture model, the calculation of the 1-hour timelag fuel moisture model requires daily temperature [°F], relative humidity [%] and fraction of sky cover at early to midafternoon time (Bradshaw et al. 1983).

Formula

When fuel sticks are not used, the 10-hour fuel moisture \(MC_{10}\) [%] for midafternoon observation time is estimated in a manner similar to that for the 1-hour fuel moisture model (Cohen & Deeming 1985):

\[MC_{10}=1.28\cdot{EMC_{f/a}}\]

where \(EMC_{f/a}\) is the same \(EMC\) used to calculate the 1-hour timelag dead fuel moisture model.

NB: According to Bradshaw et al. (1983), this model works well for early afternoons in strong continental areas at the approximate latitude of Nebraska (~41°N) in the late summer, but tends to underpredict fuel stick moisture under other conditions.

The 10-hour timelag fuel moisture model is supposed to be calculated on a daily basis. The meteorological data used for its calculation have to be recorded at early to mid-afternoon time (1 to 3 pm).

References

Deeming et al. (1977)
Bradshaw et al. (1983)