Datasets affected

• HRES
• ENS

Resolution

Unchanged

Meteorological content

• Non- orographic gravity wave scheme
• New trace gas climatology derived from the GEMS project
• Assimilation of cloud-affected radiances for infra-red instruments
• Improved assimilation of land-surface sensitive channels
• Assimilation of total-column water vapour data from the MERIS instrument (over land)
• Variational bias correction for ozone satellite data
• Improved quality control (using Huber norm) of conventional observations
• Improved background-error statistics for humidity; new humidity formulation in 4D- Var
• Weak-constraint 4D- Var taking into account systematic model errors in the stratosphere
• Further revision of the snow scheme (re-whitening, melting, ...)
• Wave damping in wind input source term for ocean waves
• Routine monitoring of soil moisture observations from Metop-A ASCAT

• Revised stochastic physics

Meteorological impact

• Northern hemisphere: statistically significant improvement in the tropospheric scores.
• European: weaker statistical significance.
• Southern hemisphere impact is essentially neutral.
• An increased negative temperature bias is present at around 100 hPa. However, there is evidence that the quality of the analysis of temperature in the stratosphere has improved, as seen from an improved fit between observations and background fields.
• The revision of the snow scheme has led to improved (colder) 2m-temperature in North America and Northern Asia in April and May.
• Temperature over Europe is not significantly changed.

• improved probabilistic scores for temperature at 850 hPa in the tropics.

Resources

ECMWF Newsletter: See Newsletter 121