SMHI MESAN operational OI settings

[cristianlussana]

Special thanks to Susanna Hopsch from SMHI for providing the list of values for the GridPP parameters associated with the variables mentioned below, which include: 2m temperature, 2m dewpoint temperature, 2m relative humidity, 2m wet bulb temperature, 10m u-wind, 10m v-wind, 10 gust, MSLP (mean sea level pressure), pressure surface, cloud base, cloud top, total cloud amount, low cloud cover, medium cloud cover, high cloud cover, precip. 1 hour, precip. 3 hours, precip. 12 hours, precip. 24 hours, snowfall 1 hour, snowfall 3 hour, snowfall 12 hour, snowfall 24 hour, 2m maximum temperature, 2m minimum temperature, visibility, frozen part of precipitation, precipitation type.

Air temperature analysis (2m temperature)

• Background model: MEPS, control member at 2.5km
• Observations: synop, swedish road authority weather stations (VViS)
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 30 km
• Vertical length scale: 200 m
• Land area fraction length scale: 1.0 (i.e. using land area fraction from MEPS)
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Elevation gradient (-6.5°C/km)

Note

2m maximum temperature and 2m minimum temperature are obtained with the same parameters reported above, except only synop stations are used.

Dew temperature analysis (2m dewpoint temperature)

• Background model: MEPS, control member at 2.5km
• Observations: synop
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 30 km
• Vertical length scale: 200 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Elevation gradient (-6.5°C/km)

Note

2m relative humidity and 2m wet-bulb temperature are diagnosed parameter from gridpp

10m u-wind / v-wind

• Background model: MEPS, control member at 2.5km
• Observations: synop, VViS
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 30 km
• Vertical length scale: 100 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Elevation gradient (5.5 (m/s)/km)

Wind gust

• Background model: MEPS, control member at 2.5km
• Observations: synop
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 60 km
• Vertical length scale: 300 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Elevation gradient (5.5 (m/s)/km)

Mean Sea Level Pressure

• Background model: MEPS, control member at 2.5km
• Observations: synop
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 80 km
• Vertical length scale: 300 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Bilinear Interpolation

Pressure near the surface

• Background model: MEPS, control member at 2.5km
• Observations: synop
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 30 km
• Vertical length scale: 200 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Elevation gradient (-12 hPa/ 100 m)

Cloud base / Could top

• Background model: MEPS, control member at 2.5km
• Observations: synop (base), satellite as superobs (top)
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 30 km
• Vertical length scale: 200 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Elevation gradient (0m/km; treating observations as relative local ground)

Total cloud amount / Low cloud cover / Medium cloud cover / High cloud cover

• Background model: MEPS, control member at 2.5km
• Observations: synop (base & amount) & satellite as superobs (amount)
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 30 km
• Vertical length scale: 200 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Bilinear Interpolation

Total Precipitation (1h / 3h / 12h / 24h)

• Background model: MEPS, control member at 2.5km
• Observations: Synop & radar composite accumulation as superobs
• OI function: optimal_interpolation
• Structure function: Barnes
• Horizontal length scale: 42.5 km
• Vertical length scale: 1750 m
• Land area fraction length scale: 1.0
• Max points: 50
• Sigma: 0.3
• allow_extrapolation: False
• observation operator: Bilinear Interpolation

Note

Snowfall totals over 1h / 3h / 12h / 24h are diagnosed variables from other analyzed variables
Visibility , Frozen part of precipitation and Precipitation type are also diagnosed variables from other analyzed variables