Page History

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The page will be updated as required. It was last changed on 2004.0607.2019.

For a record of changes made to this page please refer to Document versions .

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The timetable represents current expectations and may change in light of actual progress made.

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• Vertical resolution increased from 60 levels to 137 levels, matching that used at ECMWF for NWP. This includes moving the model top from 0.1 hPa to 0.01 hPa.
• New nitrate and ammonium aerosol species, coupled to the gas-phase nitrogen chemistry. See new model parameters below. This is a major expansion of the aerosol species represented in the model, giving a more complete representation of the species which contribute to e.g. PM_2.5 over Europe.

• Sulfur species (SO₂ and SO₄) coupled between chemistry and aerosol schemes. See discontinued parameters below. This brings a greater consistency between the chemistry and aerosol products related to the sulfur cycle.

• Online calculation of dry deposition velocities for trace gases. This was already in place for aerosols in 45r1, and allows the deposition scheme to better account for variations in surface properties..
• Updates to wet deposition parameterisations. This brings improvements in the distinction between scavenging by liquid and ice, and harmonises the treatment for aerosols and trace gases.
• Updates to chemical reaction rates following latest recommendations by JPL/IUPAC.

Impact of the new cycle

This upgrade introduces some significant changes that will allow better evolution of the CAMS forecasting system products and their quality on the long term. The main direct impact seen for this upgarde is a significant improvement of the Particulate Matter (PM) values and some degradation of the stratospheric ozone profile, although total column ozone values have no tbeen changed. For all other species we confirm very similar performeance to the previous forecastsing system. In summary:

• Pronounced improvement of surface PM2.5 and PM10 forecasts, especially during night time, by changes to the diurnal cycle of emissions and the introduction of injection heights for biomass burning emissions .
• The changes in composition of aerosols (adding nitrate and ammonium aerosol) create a small increase or no increase in the total Aerosol Optical Depth (AOD) depending on the season. An increase of sulphate aerosol is seen in particular at high latitudes of the northern hemisphere, but less in highly polluted areas in East Asia. There is less organic aerosol, especially at high latitudes. Globally there is less sea salt AOD. Mean dust AOD is slightly increased, and there is in particular more dust in North Africa and less in East Asia. 
• Tropospheric ozone shows generally higher correlations with surface and airborne observations, but the bias is slightly increased near the surface. The change in the upper troposphere is neutral.
• CO results are somewhat mixed with slightly increased biases in some areas and slightly decreased biases in other areas.
• Tropospheric NO2 values have not significantly changed.
• Stratospheric O3 column values show a slight decrease in bias, but the vertical profile has generally changed with a marked positive bias between 25 and 32 km altitude and a negative bias between 30 and 40 km altitude.

The new cycle has been new cycle is being validated by the CAMS Validation team and the results will be presented in a a validation report shortly. 

Technical details of the new cycle

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