Assimilation of IASI Ozone‐Sensitive Channels in Preparation for an Enhanced Coupling Between Numerical Weather Prediction and Chemistry Transport Models

Abstract

In this study, IASI ozone-sensitive channels have been assimilated in 1D-Var data assimilation combined with realistic ozone background coming from a MOCAGE (Modèle de Chimie Atmosphérique à Grande Echelle) Chemistry Transport Model (CTM) as a first stage of coupling between Numerical Weather Prediction (NWP) and MOCAGE CTM at Météo-France for global model ARPEGE (Action de Recherche Petite Echelle Grande Echelle). To evaluate the impact of ozone-sensitive channels on analyses, databases of 161 temperatures, humidity, and ozone radiosondes across the globe during a 1-year period have been considered. Ozone forecast from MOCAGE CTM was evaluated with radiosondes and used as input for the Radiative Transfer Model (RTM) RTTOV. Statistics of IASI observations minus simulations show that the use of ozone from MOCAGE CTM allows to better simulate IASI ozone-sensitive channels. The Desroziers method is used to diagnose observation error covariance matrix and estimate realistic ozone observation standard errors taking into account cross-correlations between IASI channels. The background error covariance matrix for ozone is estimated using radiosondes. A control run assimilating 123 IASI operational channels is compared to an experiment which assimilates, in addition, 15 IASI ozone-sensitive channels. Results show potential benefits of IASI ozone-sensitive channels combined with realistic ozone from MOCAGE CTM to improve temperature, humidity and ozone analyses simultaneously. This work is an encouraging first step for the enhancing of the coupling between the global model ARPEGE and MOCAGE CTM.

Update of Infrared Atmospheric Sounding Interferometer (IASI) channel selection with correlated observation errors for numerical weather prediction (NWP)

“…Note that channel biases between 645 and 770 cm −1 are less than 0.5 K with standard deviations between 0.3 and 0.6 K. The channels of the atmospheric window between 770 and 1000 cm −1 have approximately the same bias values, with biases less than 0.5 K and standard deviations between 0.2 and 0.7 K. The largest values are obtained with the channels in the ozone absorption band between 1000 and 1070 cm −1 with biases between 1.0 and 6.0 K and standard deviations between 0.5 and 2.0 K. These high values are mainly due to the ozone biases found in the MOCAGE CTM. It is able to model the ozone variability correctly but tends to overestimate the ozone concentration (up to 0.75 ppmv) between 300 and 40 hPa and underestimate it (up to 2.5 ppmv) between 30 and 0.1 hPa (Coopmann et al, 2018). These errors in ozone concentrations therefore have a direct impact on the modelling of radiative transfer and on the simulation of IASI channels sensitive to this species.…”

“…Currently at Météo-France, the three IASI sounders on board the Metop-A, Metop-B and Metop-C polar satellites are used in the four-dimensional variational (4D-Var) data assimilation system (Rabier et al, 2000) for the Action de Recherche Petite Échelle Grande Échelle (ARPEGE) global model (Courtier et al, 1991). The 4D-Var method consists of correcting a background from a short-range forecast (Lorenc, 1986;Courtier et al, 1994) by observations along an assimilation window, allowing users to estimate the atmospheric state. This "analysis" state is thus used as initial condition in the NWP models.…”

The development of the Atmospheric Measurements by Ultra-Light Spectrometer (AMULSE) greenhouse gas profiling system and application for satellite retrieval validation

“…Flight simulation software is used to estimate the trajectories and the landing point of the probe. This estimation is based on the wind forecasts from both Météo-France operational numerical weather prediction models: the mesoscale model AROME (Applications de la Recherche à l'Opérationnel à Méso-Echelle; Seity et al, 2011;Brousseau et al, 2016) and the global model ARPEGE (Action de Recherche Petite Echelle Grande Echelle; Courtier and Geleyn, 1988;Déqué et al, 1994). Hypotheses are made about both the ascending and the descending speed of the system and the release of the carrier balloon in order to run a first simulation.…”

The evolution of AMULSE (Atmospheric Measurements by Ultra-Light Spectrometer) and its interest in atmospheric applications. Results of the Atmospheric Profiles Of GreenhousE gasEs (APOGEE) weather balloon release campaign for satellite retrieval validation

“…Such an approach can also be used at the pixel to retrieve profiles. Indeed, (Coopmann et al, 2018) study…”

“…Soundings of 2017-06-01 to 10 UTC, 2017-07-04 to 02 UTC, 2017-07-04 to 09 UTC and 2017-07-04 to 12 UTC are selected for that case study. The methodology and techniques used in this study are the same as those used in (Coopmann et al, 2018).…”