Forecasting carbon weather: what are the benefits of using high resolution?
Abstract
We present the latest high resolution (9 km in the horizontal) CO2 and CH4 forecasts from the Copernicus Atmosphere Monitoring Service (CAMS). Global analyses and 5-day forecasts of CO2 and CH4 are produced daily using the ECMWF C-IFS (Integrated Forecasting System for atmospheric Composition) at its native resolution using a variety of prescribed and modelled fluxes for the land vegetation. The forecasts are initialized with C-IFS 4D-Var atmospheric analyses incorporating a wealth of meteorological observations in addition to CO2 and CH4 satellite products from GOSAT and IASI. To assess the impact of the high resolution, simulations are performed at different resolutions (80 km, 40 km, 16 km and 9 km) and evaluated using root-mean-square errors and correlations with respect to in situ surface and airborne observations and TCCON data. Our results show that the CO2 and CH4 synoptic variability is generally better represented at high resolution since the transport, topography and surface flux heterogeneity also improve with resolution. However, the high resolution can also lead to deterioration of the forecast close to emission hotspots, highlighting uncertainties in the fluxes that would be more diffused at lower resolutions. We find that the forecasts are useful for the assessment of the small-scale variability of CO2/CH4 which cannot be included in coarser resolution models. These representation errors need to be considered when assimilating in situ data and high resolution satellite data such as GOSAT and OCO-2. The real time provision of the CO2 and CH4 forecasts by CAMS also means that they are useful as as boundary conditions for regional modelling studies and for planning field experiments.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A11B0010P
- Keywords:
-
- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3315 Data assimilation;
- ATMOSPHERIC PROCESSES