Quantifying uncertainties due to chemistry modelling – evaluation of tropospheric composition simulations in the CAMS model (cycle 43R1)

Abstract

Abstract. We report on an evaluation of tropospheric ozone and its precursor gases in three atmospheric chemistry versions as implemented in the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS), referred to as IFS(CB05BASCOE), IFS(MOZART) and IFS(MOCAGE). While the model versions were forced with the same overall meteorology, emissions, transport and deposition schemes, they vary largely in their parameterisations describing atmospheric chemistry, including the organics degradation, heterogeneous chemistry and photolysis, as well as chemical solver. The model results from the three chemistry versions are compared against a range of aircraft field campaigns, surface observations, ozone-sondes and satellite observations, which provides quantification of the overall model uncertainty driven by the chemistry parameterisations. We find that they produce similar patterns and magnitudes for carbon monoxide (CO) and ozone (O3), as well as a range of non-methane hydrocarbons (NMHCs), with averaged differences for O3 (CO) within 10 % (20 %) throughout the troposphere. Most of the divergence in the magnitude of CO and NMHCs can be explained by differences in OH concentrations, which can reach up to 50 %, particularly at high latitudes. There are also comparatively large discrepancies between model versions for NO2, SO2 and HNO3, which are strongly influenced by secondary chemical production and loss. Other common biases in CO and NMHCs are mainly attributed to uncertainties in their emissions. This configuration of having various chemistry versions within IFS provides a quantification of uncertainties induced by chemistry modelling in the main CAMS global trace gas products beyond those that are constrained by data assimilation.

Description and evaluation of the tropospheric aerosol scheme in the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System (IFS-AER, cycle 45R1)

“…In all, the source of sulfur dioxide from oceanic DMS stands at 30 Tg yr −1 on average. The conversion of sulfur dioxide into particulate sulfate is treated in a very simple way following Huneeus (2007). In cycles 43R1 and before, conversion was parameterized only as a function of latitude as a proxy for the abundance of the OH radical.…”

Added Value of Aerosol-Cloud Interactions for Representing Aerosol Optical Depth in an Online Coupled Climate-Chemistry Model over Europe

“…This reanalysis is the latest global reanalysis dataset of atmospheric composition produced by the European Centre for Medium-Range Weather Forecasts (ECMWF), consisting of three-dimensional time-consistent atmospheric composition fields, including aerosols and chemical species with a horizontal resolution of 80 km. This reanalysis has been extensively evaluated for aerosols and gas-phase pollutants against observations during the years 2003-2016 [59,60], finding an error generally ranging from 10% to 20%. Focusing on AOD, CAMS reanalysis improves the skill of other existing chemistry reanalyses when compared against AERONET observations, indicating a very slight negative monthly bias of −0.007 over Europe [59].…”

Quantifying burning efficiency in Megacities using NO2 / CO ratio from the Tropospheric Monitoring Instrument (TROPOMI)

“…The CAMS-derived conversion factor varies <10 % compared with the standard value of 1.32, introducing a <10 % uncertainty in the inventory derived emission ratio. However, given the uncertainty in the CAMS simulated urban NO, NO2 and OH concentrations (Huijnen et al, 2019) the actual uncertainty is probably higher. Additionally, TROPOMI underestimates NO2 column by 7 % to 29.7 % relative to MAX-DOAS ground based measurement in European cities (Lambert, et al, 2019).…”