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

The Chicken Thigh Adductor Profundus Free Muscle Flap: A Novel Validated Non-Living Microsurgery Simulation Training Model.

BACKGROUND: Simulation training is becoming an increasingly important component of skills acquisition in surgical specialties, including Plastic Surgery. Non-living simulation models have an established place in Plastic Surgical microsurgery training, and support the principles of replacement, reduction and refinement of animal use. A more sophisticated version of the basic chicken thigh microsurgery model has been developed to include dissection of a type 1-muscle flap and is described and validated here. METHODS: A step-by-step dissection guide on how to perform the chicken thigh adductor profundus free muscle flap is demonstrated. Forty trainees performed the novel simulation muscle flap on the last day of a 5-day microsurgery course. Pre- and post-course microvascular anastomosis assessment, along with micro dissection and end product (anastomosis lapse index) assessment, demonstrated skills acquisition. RESULTS: The average time to dissect the flap by novice trainees was 82±24 minutes, by core trainees 90±24 minutes, and by higher trainees 64±21 minutes (P=0.013). There was a statistically significant difference in the time to complete the anastomosis between the three levels of training (P=0.001) and there was a significant decrease in the time taken to perform the anastomosis following course completion (P<0.001). Anastomosis lapse index scores improved for all cohorts with post-test average anastomosis lapse index score of 3±1.4 (P<0.001). CONCLUSIONS: The novel chicken thigh adductor profundus free muscle flap model demonstrates face and construct validity for the introduction of the principles of free tissue transfer. The low cost, constant, and reproducible anatomy makes this simulation model a recommended addition to any microsurgical training curriculum

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

Simultaneous determination of continental surface emissivity and temperature from NOAA 10/HIRS observations: Analysis of their seasonal variations

International audienceContinental surface infrared emissivity strongly depends on the wavelength and on the type of the surface. Emissivity values as low as 0.7 may be observed around 8-10 μm or, at shorter wavelengths, around 4 μm, particularly over desert regions. Satellite observations are very sensitive to emissivity variations: At 11 μm an uncertainty as small as 2% may lead to a variation of up to 0.5K in brightness temperature. An accurate and coherent, i.e., simultaneous, determination of surface temperature and emissivity is essential to greatly improve the estimation of the longwave surface energy budget and, consequently, to improve the performance of surface-atmosphere interaction models. On the basis of a space differential approach and a nonlinear regression inference method, 4 years of NOAA 10 observations (July 1987 to June 1991) over northern Africa (5°N-30°N and 20°W-60°E) have been interpreted in terms of surface emissivity at three wavelengths, namely, 11.1 μm, 8.3 μm, and 4 μm, corresponding to atmospheric windows, and surface temperature, actually, "skin" temperature. Emissivity maps at a resolution of 1° × 1° and 1 month reveal strong signatures of sand at 8.3 and 4.0 μm and of carbonates at 11.1 μm. Time series of zonal means may bring into evidence important seasonal variations as, for example, over regions of savannas: from 5% at 11.1 μm (peak to peak) to 15% at 4 μm. They are shown to be in phase with the precipitation and 1 month ahead of the Normalized Difference Vegetation Index time series. The mean uncertainty may be theoretically estimated on the order of less than 2% for the emissivity at 11.1 μm and of 1.6K for the surface temperature

First global measurement of midtropospheric CO<SUB>2</SUB> from NOAA polar satellites: Tropical zone

International audienceMidtropospheric mean atmospheric CO2 concentration is retrieved from the observations of the NOAA series of polar meteorological satellites, using a nonlinear regression inference scheme. For the 4 years of the present analysis (July 1987 to June 1991), monthly means of the CO2 concentration retrieved over the tropics (20°N to 20°S) from NOAA 10 show very good agreement with what is presently known. Not only the phase of the seasonal variations (location of the peaks) but also their amplitude and their latitudinal evolution match quite well recent in situ observations made by properly equipped commercial airliners measuring in an altitude range similar to the one favored by the satellite observations. Moreover, the annual trend inferred corresponds to the known increase in the concentration of CO2 as a result of human activities. Also, the impact of El Niño-Southern Oscillation events is clearly seen and confirms analyses of in situ or aircraft observations and of model simulations. Forty-eight maps of monthly mean midtropospheric CO2 concentration have been produced at a resolution of 15° × 15°. A rough estimate of the method-induced standard deviation of these retrievals is of the order of 3.6 ppmv (around 1%). The coming analysis of the almost 25 years of archive already accumulated by the NOAA platforms should contribute to a better understanding of the carbon cycle. A simulation of the extension of the method to the next generation high-spectral-resolution instruments, with very encouraging results, is presented

Impact of tropical biomass burning emissions on the diurnal cycle of upper tropospheric CO 2 retrieved from NOAA 10 satellite observations

International audienceof monthly mean upper tropospheric CO 2 mixing ratios over the tropics are retrieved from the observations, at 0730 LT (day) and 1930 LT (night) local time, of the meteorological satellite NOAA 10. Analysis of night minus day differences (N-DD) shows large diurnal variations of CO 2 , of the order of 2-3 ppm, during months and over regions affected by biomass burning. The patterns of these diurnal variations are in very good agreement with the diurnal and seasonal variations of biomass burning activity. We interpret them as the signal of CO 2 plumes being rapidly uplifted by fire-induced convection into the upper troposphere during the daytime peak of fire activity and then being rapidly dispersed at night by large-scale atmospheric transport. The upper air CO 2 diurnal cycle closely follows the seasonal distribution of burned areas from the European Space Agency's monthly Global Burnt Scar satellite product, which is recognized as yielding reasonable estimates of burned areas for large and presumably intense fires. The largest N-DD values are found in 1990 over southern Africa in agreement with the reported interannual variability of fire activity. However, the magnitude of these extreme signatures, on the order of 5 ppm locally, is larger than what can reasonably be expected from either in situ observations or from simulations, suggesting some contamination of the N-DD retrieval by fire emission products other than CO 2. It is concluded from a detailed sensitivity analysis that the presence of high-altitude and large optical depth aerosols, or of elevated tropospheric ozone concentrations, as are often encountered in fire plumes, may significantly contaminate the retrieved CO 2 signal (by up to 2-3 ppm for extreme events). The possible contaminating effects of undetected fire-induced thin cirrus (optical depths less than 0.05 at 14 mm) are also quantified. Citation: Chédin, A., S. Serrar, N. A. Scott, C. Pierangelo, and P. Ciais (2005), Impact of tropical biomass burning emissions on the diurnal cycle of upper tropospheric CO 2 retrieved from NOAA 10 satellite observations