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outputVariablesObs.md

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Required model output variables

The absolute minimal results to provide in the intercomparison are the following:

  • 3-hourly 3D (lat, lon, time) variables in the table below, interpolated along relevant observation stations and campaigns
  • 3-hourly 4D BrO,T,P data (lat, lon, lev, time) in the table below, processed appropriately for comparison to satellite BrO observations
  • 3-hourly (or daily) 3D variables that define surface conditions (sea ice, etc) in the table below (lat, lon, time)
  • The altitute of lowest model level, 2D information (lat, lon)

We strongly recommend that all the full 2D/3D/4D fields in the table below are saved, so that interpolations and analysis can be redone in case of errors. Please also keep these files on your own servers for comparison of monthly / weekly averages, which we will do in a second step.

Variable Unit Dimensions Frequency name in file
Surface $O_3$ mixing ratio ppbv 3 3-Hourly O3_surface_ppbv
Surface BrO mixing ratio ppbv 3 3-Hourly BrO_surface_ppbv
Surface dry sea salt aerosol mass concentration < 10 ${\mu}m$ diameter $\mu g/m^{3} (ambient)$ 3 3-Hourly SSA_surface_PM10_mass
2-meter air temperature K 3 3-Hourly T2_K
Surface pressure Pa 3 3-Hourly PSurf_Pa
10-m wind speed m/s 3 3-Hourly W10_m_s
Boundary layer height m 3 3-Hourly PBLH_m
BrO mixing ratio $ppbv$ 4 3-Hourly BrO_ppbv
Air temperature K 4 3-Hourly T_K
Air pressure Pa 4 3-Hourly P_Pa
Sea ice concentration % 3 3-Hourly frac_sea_ice
$Br_2$ emissions $moles/m^{2}$ accumulated over 3 hours 3 3-Hourly Br2_emiss_mol_m2
Sea salt aerosol emissions ${mg/m^{2}}$ accumulated over 3 hours 3 3-Hourly SSA_emiss_mg_m2
Altitude of lowermost model level m AGL + m ASL 2 - Alt_lev0_m
Ground elevation in the model (m ASL) m ASL 2 - Alt_GL_m

In addition, the following information should be saved:

  • Model grid dimensions: time, latitude, longitude, layers, levels
  • Model information/attributes: provider, model, version, creation_date

Highly recommended model output

If some of these variables cannot be saved by your model, saving some is better than none! Please keep these files on your own servers for comparison of monthly / weekly averages, which we will do in a second step.

Variable Unit Dimensions Frequency name in file
$O_3$ mixing ratio $ppbv$ 4 3-Hourly O3_ppbv
Sea salt aerosol mass concentration < 10 ${\mu}m$ $\mu g/m^{3}$ 4 3-Hourly SSA_PM10_mass
Sea salt aerosol number concentration < 10 ${\mu}m$ # $/m^{3}$ 4 3-Hourly SSA_PM10_number
$PM_{2.5}$ mass ${\mu}g/m^{3}$ 4 3-Hourly PM25_mass
$PM_{10}$ mass ${\mu}g/m^{3}$ 4 3-Hourly PM10_mass
Total aerosol mass ${\mu}g/m^{3}$ 4 3-Hourly PM_mass
Surface Wind speed $m/s$ 3 3-Hourly WS_surface_m_s
Surface Wind direction $^\circ$ 3 3-Hourly WD_surface
Surface Relative or specific humidity % or $kg/kg$ 3 3-Hourly RH_surface
Surface $Br_2$ mixing ratio $ppbv$ 3 3-Hourly Br2_surface_ppbv
Surface OH mixing ratio $ppbv$ 3 3-Hourly OH_surface_ppbv
Surface $HO_2$ mixing ratio $ppbv$ 3 3-Hourly HO2_surface_ppbv
$Br_2$ emissions from surface snow $moles/m^{2}$ accumulated over 3 hours 3 3-Hourly Br2_emiss_surface
$Br_2$ emissions from blowing snow $moles/m^{2}$ accumulated over 3 hours 3 3-Hourly Br2_emiss_bs
$Br_2$ emissions from sea spray $moles/m^{2}$ accumulated over 3 hours 3 3-Hourly Br2_emiss_ssa
Sea salt aerosol emissions from blowing snow $mg/m^{2}$ accumulated over 3 hours 3 3-Hourly SSA_emiss_bs
Sea salt aerosol emissions from sea spray $mg/m^{2}$ accumulated over 3 hours 3 3-Hourly SSA_emiss_ss

Nice-to-have model output

If some of these variables cannot be saved by your model, saving some is better than none! Please keep these files on your own servers for comparison of monthly / weekly averages, which we will do in a second step.

Variable Unit Dimensions Frequency name in file
$Br_2$ mixing ratio $ppbv$ 4 3-Hourly Br2_ppbv
OH mixing ratio $ppbv$ 4 3-Hourly OH_ppbv
$HO_2$ mixing ratio $ppbv$ 4 3-Hourly HO2_ppbv
HOBr mixing ratio $ppbv$ 4 3-Hourly HOBr_ppbv
HBr mixing ratio $ppbv$ 4 3-Hourly HBr_ppbv
ClO mixing ratio $ppbv$ 4 3-Hourly ClO_ppbv
$Cl_2$ mixing ratio $ppbv$ 4 3-Hourly Cl2_ppbv
HOCl concentration $ppbv$ 4 3-Hourly HOCl_ppbv
HCl mixing ratio $ppbv$ 4 3-Hourly HCl_ppbv
IO mixing ratio $ppbv$ 4 3-Hourly IO_ppbv
$I_2$ mixing ratio $ppbv$ 4 3-Hourly I2_ppbv
NO mixing ratio $ppbv$ 4 3-Hourly NO_ppbv
NO2 mixing ratio $ppbv$ 4 3-Hourly NO2_ppbv
Wind speed $m/s$ 4 3-Hourly WS
Wind direction $^\circ$ 4 3-Hourly WD
Relative humidity % or $kg/kg$ 4 3-Hourly RH
Specific humidity $kg/kg$ 4 3-Hourly Q
Rate of het. Br2 formation on all aerosols \mol $/cm^{3}$ accumulated over 3 hours 4 3-Hourly het_Br2_rate
$O_3$ dry deposition $g/m^{2}/hr$ accumulated over 3 hours 3 3-Hourly o3_dry_dep
Sea ice age years 3 3-Hourly ice_age_years
Br2 photolysis frequency $1/s$ 4 3-Hourly j_Br2

Station locations for data interpolation

Model results should also be provided interpolated in x/y/time at the lowest model level as a time series (3 hourly output). Please use this output file format for your extraction with one file per station.

Station name Lat Lon Measurement altitute (meters ASL)
Utqiagvik 71.323 -156.611 11
Tiksi 71.58617 128.91823 10
Summit 72.578 -38.459 3216
Nord 81.600 -16.670 20
Alert 82.49915 -62.34153 210
Zeppelin 78.910 11.888 474
Eureka 79.9830 -85.950 0

Buoy locations for data interpolation - 2012

A text file with hourly locations of O-Buoy 4 and O-Buoy 6 is provided here for models to interpolate data to their locations. Results should be provided interpolated in x/y/time at the lowest model level as a time series (3 hourly output). Please use this output file format for your extraction.

Ship track location for data interpolation - 2020

A text file with the hourly location of the MOSAiC expedition is provided here for models to interpolate their data to the Polarstern location. Results should be provided interpolated in x/y/time at the lowest model level as a time series (3 hourly output). Please use this output file format for your extraction.

Ozone sonde locations for data interpolation - 2012 and 2020

For models that keep 3 hourly ozone data, text files with 3D location and time of ozone sonde profiles will be provided for interpolation (future work!). We plan to ask for netcdf files, an example is found here.

Satellite comparison

Models should plan to provide NetCDF files of model output to U. Bremen and they will compare the model fields to their satellite retrievals. Data should be provided on model levels. The following information is needed in the files:

  • NetCDF dimensions: time, latitude, longitude, model level number
  • NetCDF 4d-variables: BrO mixing ratio [ppbv] and temperature [K] at level centers, pressure [Pa] at level interfaces (or at model level centers and Bremen will apply an interpolation to estimate P at interfaces)
  • NetCDF 2(3)d-variable: surface altitude [m]
  • NetCDF attributes: provider, model, version, creation_date

Spatial and temporal resolution should be as high as possible. For satellite comparison, please save hourly (or 3 hourly) output of these fields.

If you are planning to participate in the comparison to satellite data, please provide a small test file to Andreas Richter (richter@iup.physik.uni-bremen.de) and Bianca Zilker (bianca@iup.physik.uni-bremen.de) to ensure that they can deal with the file format.