Reports

From 2017-05-11 to 2017-05-24 we swapped the eddy system on the Tonzi tower from the older CR1000/digital-sonic/analog-7500A system to the newer 7500A/analog-sonic system.  During this time period both systems ran side by side.

CR1000/digital-sonic/analog

Sonic sn 000019, IRGA sn 0976: This system collected data on the CR1000 using a CFM card.  The CR1000 ran at 10Hz reading the serial stream from the Gill sonic.  The Gill sonic digitized the analog outputs (H2O and CO2) from the Licor LI-7500 IRGA and fed them the CR1000 through its serial data stream.

7500A/analog-sonic

Sonic sn 170523, IRGA sn 0041: This system uses Licor's LI-7550 box to record the IRGA and sonic data to a USB drive at 20Hz.  In this case the sonic U, V, W and SOS data is being output from the sonic as analog signals and the LI-7550 box is digitizing these signals and saving it with the IRGA data.  The newer model of sonic has a more linear temperature response.  The IRGA is an older 7500 which has been upgraded to the new 7500A interface.  This IRGA also had a new lamp and detector installed in 2013.

30min averages were computed from both systems for comparison.

TODO: add variances - covariances?

Figure 1. Wind Speed: The wind speed from the two systems it right on.

Figure 2. Speed of Sound:  The older Gill Wind Master sonic anemometers are known to have a curve in their SOS response.  The newer model fixes this problem.

Figure 3. CO2 time series: There is a change in the CO2 (and H2O) late on the 16th or early on the 17th.  There was field trip to the Tonzi site on the 16th but more likely there was a little rain that night that got the fresh IRGA dirty and its values dropped.  Unfortunately that leads to a split relationship in the next plot.

Figure 4. CO2: The change in signal due the the rain makes this plot messy but the I think the message is that, ignoring external factors, the relationship of CO2 from the two systems is steady.

Figure 5. H2O: Before the rain the H2O relationship was tight but after the rain not as much.  I'm not sure why this should change.

Figure 6. Ts vs Tair:  This is usually not a good fit because the sonic absolute temperature is very sensitive to the transducer separation distance.