> i kept & extended scat_dataCheck and do the checks for NaN, neg. values > and Z norm in there. > cloudbox_checkedCalc calls scat_dataCheck, but has the option to skip it > completely or to skip the Z norm check therein (oops, haven't updated the > doc yet. is coming soon.) >
doc done now, too. note: the update of cloudbox_checkedCalc might make some of your ARTS scatt calc setups to crash due to the introduced default check on the scattering matrix normalization. in this case, either set sca_mat_threshold to a higher value (default=1e-2) or skip the normalization test by setting scat_data_check to something else but 'none' and 'all' (generally, we discourage switching off the test, though). wishes, Jana ps. > Regarding normalisation, how big difference is there between >>>>> quadrature rules? 1%, 10% or 100%? Seems reasonable to at least >>>>> check that normalisation is OK inside a factor of 2. (With an >>>>> option to deactive this, if you use a solver anyhow checking >>>>> this.) >>>>> >>>> it not trivial to separate (pure) quadrature issues from grid density (when grid density is high enough, trapezoidal integration is fine...). in ARTS we hadn't used anything but trapezoidal integration before (re-)adding interfaces to DISORT and RT4 and i actually didn't go that far to check how good their quad methods perform on our standard data with its equidistant angle grids. however, what i have seen is that scattering matrix norm deviated by up to 10% from value expected from the ext-abs difference. generally, this tended to be worse for larger particles, if i remember correctly (which is straight forward as larger particles exhibit a narrower & stronger forward peak, which is hard to catch on equidistant grids). btw, the normalization threshold used by scat_dataCheck (and now also cloudbox_checkedCalc) is not directly an absolute or relative deviation of the scatt matrix norm. instead, we use the deviation rescaled by the extinction, which is effectively the absolute deviation in the scattering albedo. This was chosen in order to avoid unnecessarily high demands on low-scattering particles (when scattering is low, numerical issues might occur and trigger a relative-norm-deviation threshold, while the scattering contribution from these particles is low. an absolute-norm-deviation threshold is hard to determine as its relevance strongly depends on the total extinction). i've now set the norm threshold default to 1%. a part of the single scattering data in arts-xml-data actually does not pass the check with this threshold. as far as i've tested them, they all pass with threshold=5%. i'm not settled yet, whether i just will increase the default threshold. or whether it's more appropriate to post-process/modify the data (this goes back to the quadrature/grid density problem. the single scatt data for each individual angle gridpoint is very likely correct.). -- ===================================================================== Jana Mendrok, Ph.D. (Project Assistent) Chalmers University of Technology Earth and Space Sciences SE-412 96 Gothenburg, Sweden Phone : +46 (0)31 772 1883 =====================================================================
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