Talk:Level 3 data (velocity profilers)

Brian scannell (talk) 15:11, 30 December 2021 (CET) re. DLL_FLAGS - we have both the calculated DLL and the associated qaqc flags at the same level. It makes me wonder whether it would be better to have the R_VEL_FLAGS at level 1. They are currently at level 2 and therefore require either that the level 1 data is duplicated at level 2 or means they sit separate from the associated data. Why not have level 1 being the raw data with qaqc flags and level 2 being the data rearranged into segments (which may be the original bursts) with appropriate pre-processing (detrending) ready for the DLL calculation? It would seem cleaner and more consistent.

This would also allow for the possibility of separate qaqc flags to be defined at level 2 e.g. outlier detection based on the segmented data.

Brian scannell (talk) 16:47, 29 December 2021 (CET) re. TIME dimension comments - the requirement to define time bounds for each segment looks rather complex and I’m not sure that it adds anything. Presumably the requirement to specify bounds will not be mandatory?

Having introduced N_SEGMENT as a dimension at level 2, with TIME as a variable, we are now reverting to TIME as the dimension with N_SEGMENT as the variable. Given that TIME is now derived as the mean time for the observations in the segment, wouldn’t it be more appropriate to keep it as the variable?

Brian scannell (talk) 13:01, 30 December 2021 (CET) re. R_DEL / R_DEL5 dimension comments - R_DEL should be calculated as a function of R_DIST, which itself is a function of bin size and theta, but having defined R_DIST, it should now be the basis on which R_DEL is calculated. So for example (assuming Matlab indexing), for a central difference scheme evaluated at bin 10 i.e. R_DIST(10), the two-bin separation R_DEL(2) = R_DIST(11) - R_DIST(9), whereas for a forward difference scheme evaluated at bin 10, R_DEL(2) would be R_DIST(12) - R_DIST(10). The R_DEL(2) values will be identical, but the principle is that R_DEL is the separation distance distance the velocity observations being compared.

Also note that R_DEL units should be specified as (in meters).

Brian scannell (talk) 15:00, 30 December 2021 (CET) re. DLL_N comment - suggest reword as “number of instances when the velocity difference is evaluated, maximum is [number of profiles in segment - either max(N_SAMPLE) or possibly segment_length if redefined as number of profiles rather than time duration]"