I received the following question about how to obtain liquid water content (LWC) from the LASSO files. Others may have this question too…
Here is the main gist of the question:
I have seen in several journal articles that the 3-D distribution of cloud liquid water content (LWC) was obtained from the LASSO cloud fields data, so I accessed the website https://adc.arm.gov/lassobrowser to download the tar file that has a filename structured as sgplassodiagraw#C1.m1.YYYYMMDD.tar, but I didn’t find the 3-D distribution of LWC. I hope you can provide me with a more detailed explanation of this data.
And my reply:
You can get the simulated LWC field two different ways, both within the sgplassodiagraw tar files. The easiest is from the LES summary statistics that are calculated online and output in the wrfstat nc file. There is one wrfstat file for the whole run that contains output every 10 minutes that has been averaged over each output period via a sample every 1 minute. Within that file, we have the full volume LWC every 10 minutes in the variable CSV_LWC and the domain average profile in CSP_LWC.
The second way to get the LWC is from the wrfout nc files. These are instantaneous snapshots from the simulation every 10 minutes. We do not have the traditional LWC variable in this file, as the file is basically the traditional raw WRF model output. However, you can calculate LWC from the cloud condensate variables, QCLOUD and QRAIN. These are the mixing ratios for cloud droplets and raindrops, respectively. So, you just need to do the conversion from kgcondensate/kgdry-air to g/m3.