Custom Table when opening GRIB Files
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Description
Hello,
I'd like to open some old-school Grib files from one of our climate models. I'm using the PyNIO backend for this; which works pretty well so far -- at least the data opens! However, I am getting errors:
warning:NclGRIB: Unrecognized parameter table (center 252, subcenter 1, table 128), defaulting to NCEP operational table: variable names and units may be incorrect
So, would it somehow be possible to provide a code table to be used when opening grb files? I have files next to my output where the codes are stored. An example is below.
I can imagine something like:
ds = xr.open_dataset("/path/to/file.grb", engine="pynio", code_table="/path/to/codetab")
Would this be difficult to implement?
Cheers,
Paul
130 47 st 0.00 1.00 temperature [K]
138 47 svo 0.00 1.00 vorticity [1/s]
152 1 lsp 0.00 1.00 log surface pressure []
155 47 sd 0.00 1.00 divergence [1/s]
133 47 q 0.00 1.00 specific humidity [kg/kg]
153 47 xl 0.00 1.00 cloud water [kg/kg]
154 47 xi 0.00 1.00 cloud ice [kg/kg]
50 1 rsdscs 0.00 1.00 surface downwelling shortwave radiation flux (clear-sky) [W/m**2]
51 1 rsuscs 0.00 1.00 surface upwelling shortwave radiation flux (clear-sky) [W/m**2]
52 1 rsdscs_na 0.00 1.00 instantaneous surface downwelling shortwave radiation flux (clear-sky) [W/m**2]
53 1 rsuscs_na 0.00 1.00 instantaneous surface upwelling shortwave radiation flux (clear-sky) [W/m**2]
54 1 q2m 0.00 1.00 2m specific humidity []
55 1 rh2m 0.00 1.00 2m relative humidity []
56 1 rsdsiac 0.00 1.00 surface downwelling shortwave radiation over ice [W/m**2]
57 1 rsdswac 0.00 1.00 surface downwelling shortwave radiation over water [W/m**2]
58 1 rsusiac 0.00 1.00 surface upwelling shortwave radiation over ice [W/m**2]
59 1 rsuswac 0.00 1.00 surface upwelling shortwave radiation over water [W/m**2]
60 1 rldsiac 0.00 1.00 surface downwelling longwave radiation over ice [W/m**2]
61 1 rldswac 0.00 1.00 surface downwelling longwave radiation over water [W/m**2]
62 1 rlusiac 0.00 1.00 surface upwelling longwave radiation over ice [W/m**2]
63 1 rluswac 0.00 1.00 surface upwelling longwave radiation over water [W/m**2]
64 1 sh_vdiff 0.00 1.00 column heating due to vertical diffusion [W/m**2]
65 1 ev_vdiff 0.00 1.00 column moistening due to vertical diffusion [kg/m**2s]
66 1 ch_concloud 0.00 1.00 convective heating [W/m**s]
67 1 cw_concloud 0.00 1.00 convective moistening [kg/m**2s]
68 1 fage 0.00 1.00 aging factor of snow on ice []
69 1 snifrac 0.00 1.00 fraction of ice covered with snow []
70 1 barefrac 0.00 1.00 bare ice fraction []
71 1 alsom 0.00 1.00 albedo of melt ponds []
72 1 alsobs 0.00 1.00 albedo of bare ice and snow without ponds []
73 1 sicepdw 0.00 1.00 melt pond depth on sea-ice [m]
74 1 sicepdi 0.00 1.00 ice thickness on melt pond [m]
75 1 tsicepdi 0.00 1.00 ice temperature on frozen melt pond [K]
76 1 sicepres 0.00 1.00 residual heat flux [W/m**2]
77 1 ameltdepth 0.00 1.00 total melt pond depth [m]
78 1 ameltfrac 0.00 1.00 fract area of melt ponds on sea-ice []
79 1 albedo_vis_dir 0.00 1.00 surface albedo visible range direct []
80 1 albedo_nir_dir 0.00 1.00 surface albedo NIR range direct []
81 1 albedo_vis_dif 0.00 1.00 surface albedo visible range diffuse []
82 1 albedo_nir_dif 0.00 1.00 surface albedo NIR range diffuse []
83 1 ocu 0.00 1.00 ocean eastward velocity [m/s]
84 1 ocv 0.00 1.00 ocean northward velocity [m/s]
85 1 tradl 0.00 1.00 thermal radiation 200mb [W/m**2]
86 1 sradl 0.00 1.00 solar radiation 200mb [W/m**2]
87 1 trafl 0.00 1.00 thermal radiation 200mb (clear sky) [W/m**2]
88 1 srafl 0.00 1.00 solar radiation 200mb (clear sky) [W/m**2]
89 1 amlcorac 0.00 1.00 mixed layer flux correction [W/m**2]
91 1 trfliac 0.00 1.00 LW flux over ice [W/m**2]
92 1 trflwac 0.00 1.00 LW flux over water [W/m**2]
93 1 trfllac 0.00 1.00 LW flux over land [W/m**2]
94 1 sofliac 0.00 1.00 SW flux over ice [W/m**2]
95 1 soflwac 0.00 1.00 SW flux over water [W/m**2]
96 1 sofllac 0.00 1.00 SW flux over land [W/m**2]
97 1 friac 0.00 1.00 ice cover (fraction of grid box) []
100 1 albedo_vis 0.00 1.00 surface albedo visible range []
101 1 albedo_nir 0.00 1.00 surface albedo NIR range []
102 1 tsi 0.00 1.00 surface temperature of ice [K]
103 1 tsw 0.00 1.00 surface temperature of water [K]
104 1 ustri 0.00 1.00 zonal wind stress over ice [Pa]
105 1 vstri 0.00 1.00 meridional wind stress over ice [Pa]
106 1 ustrw 0.00 1.00 zonal wind stress over water [Pa]
107 1 vstrw 0.00 1.00 meridional wind stress over water [Pa]
108 1 ustrl 0.00 1.00 zonal wind stress over land [Pa]
109 1 vstrl 0.00 1.00 meridional wind stress over land [Pa]
110 1 ahfliac 0.00 1.00 latent heat flux over ice [W/m**2]
111 1 ahflwac 0.00 1.00 latent heat flux over water [W/m**2]
112 1 ahfllac 0.00 1.00 latent heat flux over land [W/m**2]
113 1 evapiac 0.00 1.00 evaporation over ice [kg/m**2s]
114 1 evapwac 0.00 1.00 evaporation over water [kg/m**2s]
115 1 evaplac 0.00 1.00 evaporation over land [kg/m**2s]
116 1 az0i 0.00 1.00 roughness length over ice [m]
117 1 az0w 0.00 1.00 roughness length over water [m]
118 1 az0l 0.00 1.00 roughness length over land [m]
119 1 ahfsiac 0.00 1.00 sensible heat flux over ice [W/m**2]
120 1 ahfswac 0.00 1.00 sensible heat flux over water [W/m**2]
121 1 ahfslac 0.00 1.00 sensible heat flux over land [W/m**2]
122 1 alsoi 0.00 1.00 albedo of ice []
123 1 alsow 0.00 1.00 albedo of water []
124 1 alsol 0.00 1.00 albedo of land []
125 1 ahfice 0.00 1.00 conductive heat flux [W/m**2]
126 1 qres 0.00 1.00 residual heat flux for melting sea ice [W/m**2]
129 1 geosp 0.00 1.00 surface geopotential (orography) [m**2/s**2]
134 1 aps 0.00 1.00 surface pressure [Pa]
137 1 apmeb 0.00 1.00 vertic integr tendenc of water [kg/m**2s]
139 1 tslm1 0.00 1.00 surface temperature of land [K]
140 1 ws 0.00 1.00 soil wetness [m]
141 1 sn 0.00 1.00 snow depth [m]
142 1 aprl 0.00 1.00 large scale precipitation [kg/m**2s]
143 1 aprc 0.00 1.00 convective precipitation [kg/m**2s]
144 1 aprs 0.00 1.00 snow fall [kg/m**2s]
145 1 vdis 0.00 1.00 boundary layer dissipation [W/m**2]
146 1 ahfs 0.00 1.00 sensible heat flux [W/m**2]
147 1 ahfl 0.00 1.00 latent heat flux [W/m**2]
150 1 xivi 0.00 1.00 vertically integrated cloud ice [kg/m**2]
157 47 relhum 0.00 1.00 relative humidity []
164 1 aclcov 0.00 1.00 total cloud cover []
165 1 u10 0.00 1.00 10m u-velocity [m/s]
166 1 v10 0.00 1.00 10m v-velocity [m/s]
167 1 temp2 0.00 1.00 2m temperature [K]
168 1 dew2 0.00 1.00 2m dew point temperature [K]
169 1 tsurf 0.00 1.00 surface temperature [K]
171 1 wind10 0.00 1.00 10m windspeed [m/s]
172 1 slm 0.00 1.00 land sea mask (1=land, 0=sea/lakes) []
175 1 albedo 0.00 1.00 surface albedo []
176 1 srads 0.00 1.00 net surface solar radiation [W/m**2]
177 1 trads 0.00 1.00 net surface thermal radiation [W/m**2]
178 1 srad0 0.00 1.00 net top solar radiation [W/m**2]
179 1 trad0 0.00 1.00 top thermal radiation (OLR) [W/m**2]
180 1 ustr 0.00 1.00 u-stress [Pa]
181 1 vstr 0.00 1.00 v-stress [Pa]
182 1 evap 0.00 1.00 evaporation [kg/m**2s]
184 1 srad0d 0.00 1.00 top incoming solar radiation [W/m**2]
185 1 srafs 0.00 1.00 net surface solar radiation (clear sky) [W/m**2]
186 1 trafs 0.00 1.00 net surface therm radiation (clear sky) [W/m**2]
187 1 sraf0 0.00 1.00 net top solar radiation (clear sky) [W/m**2]
188 1 traf0 0.00 1.00 net top thermal radiation (clear sky) [W/m**2]
193 1 wl 0.00 1.00 skin reservoir content [m]
194 1 slf 0.00 1.00 sea land fraction []
197 1 vdisgw 0.00 1.00 gravity wave dissipation [W/m**2]
201 1 t2max 0.00 1.00 maximum 2m temperature [K]
202 1 t2min 0.00 1.00 minimum 2m temperature [K]
203 1 srad0u 0.00 1.00 top solar radiation upward [W/m**2]
204 1 sradsu 0.00 1.00 surface solar radiation upward [W/m**2]
205 1 tradsu 0.00 1.00 surface thermal radiation upward [W/m**2]
208 1 ahfcon 0.00 1.00 conductive heat flux through ice [W/m**2]
209 1 ahfres 0.00 1.00 melting of ice [W/m**2]
210 1 seaice 0.00 1.00 ice cover (fraction of 1-SLM) []
211 1 siced 0.00 1.00 ice depth [m]
213 1 gld 0.00 1.00 glacier depth [m]
214 1 sni 0.00 1.00 water equivalent of snow on ice [m]
216 1 wimax 0.00 1.00 maximum 10m-wind speed [m/s]
217 1 topmax 0.00 1.00 max height of conv cloud tops [Pa]
223 47 aclcac 0.00 1.00 cloud cover []
229 1 wsmx 0.00 1.00 field capacity of soil [m]
230 1 qvi 0.00 1.00 vertically integrated water vapor [kg/m**2]
231 1 xlvi 0.00 1.00 vertically integrated cloud water [kg/m**2]
232 1 glac 0.00 1.00 fraction of land covered by glaciers []
233 1 snc 0.00 1.00 snow depth at the canopy [m]
235 1 abso4 0.00 1.00 antropogenic sulfur burden [kg/m**2]
236 47 ao3 0.00 1.00 ipcc ozone [kg/kg]
237 1 tropo 0.00 1.00 WMO defined tropopause height [Pa]
238 1 thvsig 0.00 1.00 stddev virt pot temp at halflev klevm1 [K]
239 47 tpot 0.00 1.00 potential temperature [K]
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start at the xarray PyNIO backend used by xr.open_dataset(..., engine="pynio") and trace how GRIB options are passed to the backend. Check whether an existing backend test covers custom engine arguments; done means a code-table path can be supplied when opening GRIB files and the reported variable names and units use it.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- backend
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100