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What's new?
Version 5.2.7 contains updates to quantization metadata,
enhanced grid area diagnostics for check_map, and bug-fixes
for ncclimo and ncremap.
Enjoy,
Charlie
NEW FEATURES (full details always in ChangeLog):
A. Version 5.2.7 implements the final (we think) CF quantization
metadata convention. The main change is that the keywords and
container variable are now "quantization" instead of
"lossy_compression".
ncks -7 -v ps,ts --qnt_alg=btr --qnt default=9 --qnt ps=13
--cmp='shf|zst' in.nc out.nc
ncks -m -C -v ps,ts,quantization_info out.nc
netcdf out {
...
float ps(time,lat,lon) ;
ps:standard_name = "surface_air_pressure" ;
ps:units = "Pa" ;
ps:quantization = "quantization_info" ;
ps:quantization_nsb = 13 ;
ps:quantization_maximum_relative_error = 6.103516e-05f ;
char quantization_info ;
quantization_info:algorithm = "bitround" ;
quantization_info:implementation = "NCO version 5.2.7" ;
float ts(time) ;
ts:standard_name = "surface_temperature" ;
ts:units = "K" ;
ts:quantization = "quantization_info" ;
ts:quantization_nsb = 9 ;
ts:quantization_maximum_relative_error = 0.0009765625f ;
} // group /
http://nco.sf.net/nco.html#qnt_alg
http://nco.sf.net/nco.html#qnt
B. ncks --chk_map now produces additional diagnostics about the
source and destination grids. Then new diagnostics are values and
locations (index, latitude, longitude) of the minimum and maximum
gridcell areas (usually in sterradians), together with the effective
quadrilateral size on Earth of the gridcell (assuming a square shaped
cell of equivalent area):
ncks --chk_map map_ne30pg2_to_cmip6_180x360_nco.20200901.nc
...
area_a min, ~dx: 4.9093515660647374e-04 sr, 141.14 km in grid A cell
[21544,+45.7267,+177.69]
area_a max, ~dx: 6.8523331840188574e-04 sr, 166.75 km in grid A cell
[9061,+0.749936,+180.75]
...
area_b min, ~dx: 2.6580860638549120e-06 sr, 10.39 km in grid A cell
[60,-42.7476,+359.25]
area_b max, ~dx: 3.0460968486221404e-04 sr, 111.18 km in grid A cell
[32272,-68.5,+135.5]
These diagnostics can be useful in identifying grid-related dynamics
issues, e.g., due to CFL conditions. This feature was inspired by
map diagnostic software from Mark Taylor (SNL).
http://nco.sf.net/nco.html#chk_map
BUG FIXES:
A. ncremap: A bug that crept into version 5.2.6 has been fixed.
Namely, the detection of empty destination gridcells was broken.
This prevented correctly adding the _FillValue attribute to some
fields with missing values. The workaround is to use version 5.2.4.
The solution is to upgrade. Thanks to Xylar Asay-Davis (LANL) for
reporting resultant problems.
B. ncclimo: A bug that crept into version 5.2.6 has been fixed.
ncclimo had stopped passing the specified processing type (-P mdl)
to internal calls to ncremap. This prevented ncremap from
automagically weighting fields from surface models by the appropriate
sub-gridscale fraction variable (landfrac for ELM+CLM, aice for CICE,
timeMonthly_avg_iceAreaCell for MPAS-Seaice). The workaround is to use
version 5.2.4. The solution is to upgrade. Thanks to Tony Bartoletti
(LLNL) for noticing resultant problems.
Full release statement at http://nco.sf.net/ANNOUNCE
--
Charlie Zender, Dept. of Earth System Science
University of California, Irvine 949-891-2429
