Correct high respiration values at PPine

[gremau]

High respiration at PPine

There are very high respiration values at PPine. This is especially true during the growing season when Fc values exceed 30 umol m^-2^ s^-1^, but values greater than 10 umol m^-2^ s^-1^ occur regularly all year. Possible reasons include:

1. Nighttime downslope drainage of high CO2 air from the canyon to the northeast of the tower.
2. Air pooling in valley reduces atmospheric mixing.
3. Advection - vague and possibly related to 1.
4. Something else...

Current solution:

1. Remove Fc during nightime periods when wind is from ~50 degrees (downcanyon winds).
2. Set some hard limits on respiration (high_CO2 filter in RBD)
3. Normalize respiration values to between 0 and 10. This seems pretty sketchy, but it happens in RBD.

This makes respiration look nice and match other arid Ponderosa sites (Metolius), but we have no idea how accurate it is.

Possible improvements to this include:

1. Better removal of periods in which advection, downslope drainage, or atmospheric pooling occur.
2. suggestions welcome...