The importance of transport model uncertainties for the estimation of CO2 sources and sinks using satellite measurements

This study presents a synthetic model intercomparison to investigate the importance of transport model errors for estimating the sources and sinks of CO2 using satellite measurements. The experiments were designed for testing the potential performance of the proposed CO2 lidar A-SCOPE, but also apply to other space borne missions that monitor total column CO2. The participating transport models IFS, LMDZ, TM3, and TM5 were run in forward and inverse mode using common a priori CO2 fluxes and initial concentrations. Forward simulations of column averaged CO2 (xCO2) mixing ratios vary between the models by s=0.5 ppm over the continents and s=0.27 ppm over the oceans. Despite the fact that the models agree on average on the sub-ppm level, these modest differences nevertheless lead to significant discrepancies in the inverted fluxes of 0.1 PgC/yr per 106 km2 over land and 0.03 PgC/yr per 106 km2 over the ocean. These transport model induced flux uncertainties exceed the target requirement that was formulated for the A-SCOPE mission of 0.02 PgC/yr per 106 km2, and could also limit the overall performance of other CO2 missions such as GOSAT. A variable, but overall encouraging agreement is found in comparison with FTS measurements at Park Falls, Darwin, Spitsbergen, and Bremen, although systematic differences are found exceeding the 0.5 ppm level. Because of this, our estimate of the impact of transport model uncerainty is likely to be conservative. It is concluded that to make use of the remote sensing technique for quantifying the sources and sinks of CO2 not only requires highly accurate satellite instruments, but also puts stringent requirements on the performance of atmospheric transport models. Improving the accuracy of these models should receive high priority, which calls for a closer collaboration between experts in atmospheric dynamics and tracer transpor

Production et caractérisation d'anticorps monoclonaux contre l'histamine

Afin de produire un anticorps monoclonal anti-histamine, des souris sont immunisées par 7 conjugués histamineprotéine en utilisant plusieurs protéines et agents de couplage. Après un premier criblage employant les protéines natives et les conjugués histamine-caséine et histamine-BSA comme antigènes pour identifier les clones qui sécrètent des anticorps monoclonaux, les hybridomes sont clonés par dilution limite et cultivés en ascites. Quatre anticorps monoclonaux ont été seléctionnés (4C9, 4D9, 7E10 .et 9D9 ) et leur spécificité a été étudiée. Les anticorps réagissent avec tous les conjugués histamine-protéine préparés. Mais, ils ne réagissent pas avec les protéines natives, les protéines dérivées ou le conjugué témoin glycine-caséine. De plus, aucune réaction croisée n'a été observée avec les 6 amines biogènes et 2 acides aminés succeptibles d'interférer dans le dosage de l'histamine. L'histamine libre non conjuguée inhibe de façon significative la liaison entre les anticorps etle conjugué histaminecaséine. L'histamine libre inhibe moins efficacement les anticorps que le dérivé histamine-benzoquinone et le conjugué histamine-caséine. L'épitope reconnu par ces anticorps semble être constitué essentiellement par la molécule d'histamine dérivée.Preparation and characterisation of Monoclonal anti-histamine antibodiesIn order to produce monoclonal antibody to histamine, mice are immunized with seven conjugates histamineprotein using several protein and coupling agents. After an initial screening using native protein and histaminecase in, histamine-BSA conjugates as antigens to identify monoclonal antibody secreting clones, the hybridomes are isolated by limiting dilution cloning and grown in ascites. Four antibodies have been selected (4C9, 409, 7E10, 909) and their specificity has been studied. The antibodies react with ail our prepared conjugates histamineprotein. But they are unreactive with native proteins, the derivative proteins, or glycine-casein conjugate. Moreover, no cross-reaction is observed with six biogenic amines and two smino acids that would interfere in the quantitation of histamine. Free unconjugated histamine significantly inhibits antibodies binding to histaminecasein. A much more lower inhibitory potency of free histamine is recorded , as compared to histaminebenzoquinone derivative and to histamine-casein. The main epitope seems encompass the molecule of histamine derived by the coupling agents

Aerosol analysis and forecast in the European Centre for Medium-Range Weather Forecasts Integrated Forecast System: Forward modeling

International audienceThis paper presents the aerosol modeling now part of the ECMWF Integrated Forecasting System (IFS). It includes new prognostic variables for the mass of sea salt, dust, organic matter and black carbon, and sulphate aerosols, interactive with both the dynamics and the physics of the model. It details the various parameterizations used in the IFS to account for the presence of tropospheric aerosols. Details are given of the various formulations and data sets for the sources of the different aerosols and of the parameterizations describing their sinks. Comparisons of monthly mean and daily aerosol quantities like optical depths against satellite and surface observations are presented. The capability of the forecast model to simulate aerosol events is illustrated through comparisons of dust plume events. The ECMWF IFS provides a good description of the horizontal distribution and temporal variability of the main aerosol types. The forecastonly model described here generally gives the total aerosol optical depth within 0.12 of the relevant observations and can therefore provide the background trajectory information for the aerosol assimilation system described in part 2 of this paper

TransCom model simulations of hourly atmospheric CO 2 : Experimental overview and diurnal cycle results for 2002

International audienceA forward atmospheric transport modeling experiment has been coordinated by the TransCom group to investigate synoptic and diurnal variations in CO 2. Model simulations were run for biospheric, fossil, and air-sea exchange of CO 2 and for SF 6 and radon for 2000-2003. Twenty-five models or model variants participated in the comparison. Hourly concentration time series were submitted for 280 sites along with vertical profiles, fluxes, and meteorological variables at 100 sites. The submitted results have been analyzed for diurnal variations and are compared with observed CO 2 in 2002. Mean summer diurnal cycles vary widely in amplitude across models. The choice of sampling location and model level account for part of the spread suggesting that representation errors in these types of models are potentially large. Despite the model spread, most models simulate the relative variation in diurnal amplitude between sites reasonably well. The modeled diurnal amplitude only shows a weak relationship with vertical resolution across models; differences in near-surface transport simulation appear to play a major role. Examples are also presented where there is evidence that the models show useful skill in simulating seasonal and synoptic changes in diurnal amplitude