I have a wind-lidar measurement from which by looking at the CNR profile I am trying to estimate the boundary layer height. Unfortunately the wind-lidar did not work throughout the period of the campaign. I have the measurement of the incoming solar radiation throughout the period. Is it advisable if I correlate the ABL height determined from the Lidar measurements to the Incoming solar radiation and then for the missing periods I use that relation to get the ABL height?
Are you only interested in daytime boundary layer heights?
I am not an expert but my intuitive response is to say that you are over-simplifying a very complex variable (boundary layer height). Why don't you test your method on another data set which is complete? Synthetically introduce gaps to a complete data set and see what you get when using radiation to estimate the height of a convective boundary layer.
As Paula mentions, it is a rather complex variable, involving quite a few processes and interactions over a number of scales (and with dimensional dependences).
The correlation you'd like to try might match up ok for (some) daytime periods on sunny (enough) days; this is generally consistent with e.g. simple models for the daytime ABL depth and its evolution.
But for e.g. nighttime, cloudy, or some other conditions (also depending on the surrounding terrain and dominant mesoscale effects), then your correlation won't give you the depth.
One might (be tempted to) try mesoscale model output as a proxy...although different PBL schemes in WRF give different ABL-depths (and distributions), if your need for hABL allows for a relatively big (e.g. 30%) error then you can do this...
Cheers, ---Mark
I can think of a couple of ways...
1. You can, with some additional measurements at the surface (sonic anemometer to calculate frictional wind), determine the Monin-Obukhov length of the surface layer. Since the surface layer is commonly accepted as being 10% of the boundary layer, then you can infer boundary layer height. This relationship has a difficult time with very stable conditions according to studies. The Monin-Obukhov also introduces a stability function to account for various atmospheric conditions. The good thing about this equation is that it uses heat flux from the surface and wind at the surface. Therefore only sonic anemometers and a radiation package are needed. This may be okay as an approximation for the daytime boundary layer, but I'd at least consider launching a couple of radiosondes to confirm the approach and test the method since conditions are rarely ideal.
2. It's difficult to estimate BL heights with a wind lidar, but people do. I've estimated the stable boundary layer height in the presence of a low-level jet, and correlated that with elastic backscatter measurements of SNR. Other people have done the same. What they do is use the wind maximum of the low-level jet as a marker to define the interface between stable layer with the layer aloft. Some LIDARs offer an SNR, which may be useful to for determining the boundary too.
Hope this helps
You don't specify what kind of "incoming solar radiation" you measure exactly. In any case, there is no known clear relationship between surface irradiance and the ABL, so I think what you try to do would simply result in noise.
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