Simulation of ozone depletion in spring 2000 with the Chemical Lagrangian Model of the Stratosphere (CLaMS) (original) (raw)
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Journal of Geophysical Research, 1999
A new middle-atmosphere general circulation model that includes the photochemistry for ozone and other chemical species (19 photolysis and 52 chemical reactions) has been constructed. The horizontal spectral resolution is T21 (about a 600 km horizontal grid spacing) with 30 layers in the vertical. Preliminary results from over 10 years of model integration are presented. The distributions of longlived species, such as N20, are rather similar to those of satellite observations in a climatological sense, although the sharp meridional gradient around 30 ø latitude is not well simulated in the model stratosphere. Neither is the double peak structure that occurs during equinox periods well reproduced. This result is consistent with the fact that the westerly phase of the semiannual oscillation is weak in this model. This may be due to the coarse resolution of the model. The seasonal evolution of the ozone column abundance is quite realistic, although the model slightly underestimates total tropical ozone. The model also underestimates ozone amounts around the equatorial tropopause. The February midlatitude number density of OH in the model upper stratosphere is about 1.8 x 107 cm -3, which is slightly less than that observed. The horizontal distributions of short-lived species, such as NO, suggest a reasonable model diurnal variation. The model has a cold bias of about 25 K in the lower stratospheric Northern Hemisphere winter and 5 K in the Southern Hemisphere winter. The model residual mean vertical velocity in the equatorial lower stratosphere is too weak (about 0.1 mm/s) during the Northern Hemisphere winter, compared with the observed (about 0.4 mm/s), while the model temperature around the equatorial tropopause is cooler than that observed.
Journal of Geophysical Research, 2002
Simultaneous balloon-borne observations of ozone (O 3) and nitrous oxide (N 2 O), a long-lived tracer of dynamical motion, are used to quantify the chemical loss of ozone in the Arctic vortex during the winter of 1999/2000. Chemical loss of ozone occurred between altitudes of about 14 and 22 km (pressures from $120 to 30 mbar) and resulted in a 61 ± 13 Dobson unit reduction in total column ozone between late November 1999 and 5 March 2000 (the date of the last balloon-borne measurement considered here). This loss estimate is valid for the core of the vortex during the time period covered by the observations. It is shown that the observed changes in the O 3 versus N 2 O relation were almost entirely due to chemistry and could not have been caused by dynamics. The chemical loss of column ozone inferred from the balloon-borne measurements using the ''ozone versus tracer'' technique is shown to compare well with estimates of chemical loss found using both the Match technique (as applied to independent ozonesonde data) and the ''vortex-averaged descent'' technique (as applied to Polar Ozone and Aerosol Measurement (POAM) III satellite measurements of ozone). This comparison establishes the validity of each approach for estimating chemical loss of column ozone for the Arctic winter of 1999/2000.
Journal of Geophysical Research, 2000
The first deployment of the ECOC electro chemical ozone cell (ECOC) instrument onboard the high-altitude research aircraft, the Geophysica M-55, took place from Rovaniemi, northern Finland, between December 23, 1996, and January 14, 1997. The ECOC data were compared against contemporaneous data from a network of balloon-borne ozone sondes. The comparison was carried out in potential vorticity-potential temperature (PV, ©) coordinates, using meteorological analyses from the European Centre for Medium-Range Forecasts. The comparison showed that ozone mixing ratios measured by ECOC are lower than those measured by ozonesonde by a small but statistically significant bias of (-5.7 5: 2.8)% at the cruising altitudes of the aircraft, 15 to 19 km. After establishing and removing the average bias, ECOC and ozonesonde data were analyzed together to follow the development of ozone distributions in the early winter Arctic stratosphere. The analysis showed no evidence of chemical ozone depletion at the cruising altitudes of the aircraft, that is, between 435 and 490 K. The absence of chemical depletion is in agreement with polar statospheric cloud (PSC) observations, which showed no PSCs at aircraft cruising altitudes, although from January 5 onwards, PSCs were observed above cruising altitudes. Results from a three-dimensional chemical transport model reproduce the basic features of the reconstructed ozone fields. However, the model does not capture the observed ozone increase during the campaign, due to weak modeled ozone vertical gradients, and indicates small ozone depletion of about 3% inside the vortex at 480 K by mid January. 14,599
C HAPTE R 6 Model Simulations of Stratospheric Ozone
2012
Model Simulations of Stratospheric Ozone Multi-dimensional models are designed to provide simulations of the large-scale transport in the stratosphere. This transport rate is combined with the local chemical production and removal rates of ozone to determine the distribution of ozone as a fu nction of longitude, latitude, height, and season. • There is strong observational evidence that heterogeneous chemistry (hydrolysis of N20s and ClON02) is oper ating on surfaces of the aerosol particles in the stratospheric sulfate layer. There is a general agreement on how this should be represented in the models. Models that include these reactions produce calculated ozone decreases (between 1980 and 1990) that are larger and in better agreement with the observed trend than those produced by models that include only gas-phase reactions. All model simulations reported here include these two reactions.
Journal of Geophysical Research: Atmospheres, 2003
We have developed a global three-dimensional chemical transport model called Model of Ozone and Related Chemical Tracers (MOZART), version 2. This model, which will be made available to the community, is built on the framework of the National Center for Atmospheric Research (NCAR) Model of Atmospheric Transport and Chemistry (MATCH) and can easily be driven with various meteorological inputs and model resolutions. In this work, we describe the standard configuration of the model, in which the model is driven by meteorological inputs every 3 hours from the middle atmosphere version of the NCAR Community Climate Model (MACCM3) and uses a 20-min time step and a horizontal resolution of 2.8°latitude  2.8°longitude with 34 vertical levels extending up to approximately 40 km. The model includes a detailed chemistry scheme for tropospheric ozone, nitrogen oxides, and hydrocarbon chemistry, with 63 chemical species. Tracer advection is performed using a flux-form semi-Lagrangian scheme with a pressure fixer. Subgrid-scale convective and boundary layer parameterizations are included in the model. Surface emissions include sources from fossil fuel combustion, biofuel and biomass burning, biogenic and soil emissions, and oceanic emissions. Parameterizations of dry and wet deposition are included. Stratospheric concentrations of several long-lived species (including ozone) are constrained by relaxation toward climatological values. The distribution of tropospheric ozone is well simulated in the model, including seasonality and horizontal and vertical gradients. However, the model tends to overestimate ozone near the tropopause at high northern latitudes. Concentrations of nitrogen oxides (NO x) and nitric acid (HNO 3) agree well with observed values, but peroxyacetylnitrate (PAN) is overestimated by the model in the upper troposphere at several locations. Carbon monoxide (CO) is simulated well at most locations, but the seasonal cycle is underestimated at some sites in the Northern Hemisphere. We find that in situ photochemical production and loss dominate the tropospheric ozone budget, over input from the stratosphere and dry deposition. Approximately 75% of the tropospheric production and loss of ozone occurs within the tropics, with large net production in the tropical upper troposphere. Tropospheric production and loss of ozone are three to four times greater in the northern extratropics than the southern extratropics. The global sources of CO consist of photochemical production (55%) and direct emissions (45%). The tropics dominate the chemistry of CO, accounting for about 75% of the tropospheric production and loss. The global budgets of tropospheric ozone and CO are generally consistent with the range found in recent studies. The lifetime of methane (9.5 years) and methylchloroform (5.7 years) versus oxidation by tropospheric hydroxyl radical (OH), two useful measures of the global abundance of OH, agree well with recent estimates. Concentrations of nonmethane hydrocarbons and oxygenated intermediates (carbonyls and peroxides) generally agree
Journal of Geophysical Research, 2003
In situ observations of ClO mixing ratios obtained from a balloonborne instrument launched in Kiruna on 27 January 2000 and on 1 March 2000 are presented. ClO mixing ratios and quasi-simultaneously observed ozone loss are compared to model simulations performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS). ClO mixing ratios are simulated initializing the model simulations for early winter conditions. Sensitivity studies are performed to explore the impact of the surface area of the background aerosol, of denitrification, and of the recently reported kinetics of the ClO self-reaction [Bloss et al., 2001] on simulated ClO. For 27 January 2000, model simulations agree with rate constants reported by Bloss et al. [2001], whereas for 1 March 2000 simulations employing rate constants reported by Bloss et al. [2001] and by Sander et al. [2000] reproduce the ClO measurements. The impact of uncertainties arising from accumulated errors along the calculated backward trajectories and uncertainties within temperatures derived from the UK Met Office are also studied. For both flights, simulated ClO show a good overall agreement with measured ClO within uncertainties arising from accumulated errors along air parcel histories. We find a layer of low ClO mixing ratios < 100 pptv between 600 and 620 K for the flight on 27 January 2000 and between 525 and 550 K on 1 March 2000. For this layer, measured ClO is substantially lower than simulated ClO. Potential causes are discussed, but the discrepancy remains unexplained at present. Furthermore, for 1 March 2000, an overall agreement is found between model simulations and measurements by the HALOE instrument of HCl and NO x (=NO + NO 2) for all altitudes considered. We conclude that denitrification occurred up to a potential temperature of %550 K (%24 km altitude) on 1 March 2000. Finally, model simulations show that between late January and 1 March, a significant ozone loss of about 0.8-1.8 ppmv is derived between 425 and 490 K of potential temperature in agreement with measured ozone loss and correlated with the enhanced ClO. For 1 March 2000, 77 ± 10 DU is obtained as an estimate of the loss in column ozone.
Geophysical Research Letters, 1998
We present box model calculations of ozone loss rates corresponding to the results of the Match experiment 1991/92. The Match technique infers chemical ozone depletion from an analysis of pairs of balloon soundings that measure ozone in the same airparcel at different points of a calculated trajectory. It allows a quantitative comparison with model results because the exposure of the observed airmasses to sunlight is well known. The model significantly underestimates the loss rates inferred for January to mid-February. Extensive sensitivity studies show that the discrepancy between model and Match results cannot be explained by the known uncertainties in the model parameters.
A domain-filling, forward trajectory model originally developed for simulating stratospheric water vapor is used to simulate ozone (O 3 ) and carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS). Trajectories are initialized in the upper troposphere, and the circulation is based on reanalysis wind fields. In addi-5 tion, chemical production and loss rates along trajectories are included using calculations from the Whole Atmosphere Community Climate Model (WACCM). The trajectory model results show good overall agreement with satellite observations from the Aura Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) in terms of spatial structure and seasonal variabil-10 ity. The trajectory model results also agree well with the Eulerian WACCM simulations. Analysis of the simulated tracers shows that seasonal variations in tropical upwelling exerts strong influence on O 3 and CO in the tropical lower stratosphere, and the coupled seasonal cycles provide a useful test of the transport simulations. Interannual variations in the tracers are also closely coupled to changes in upwelling, and the 15 trajectory model can accurately capture and explain observed changes during 2005-2011. This demonstrates the importance of variability in tropical upwelling in forcing chemical changes in the tropical UTLS. 25 1998; Wang and Dessler, 2012) all support this understanding. Back trajectory models 5992 ACPD 14, 5991-6025, 2014
Journal of Geophysical Research, 2002
Simultaneous balloon-borne observations of ozone (O 3) and nitrous oxide (N 2 O), a long-lived tracer of dynamical motion, are used to quantify the chemical loss of ozone in the Arctic vortex during the winter of 1999/2000. Chemical loss of ozone occurred between altitudes of about 14 and 22 km (pressures from $120 to 30 mbar) and resulted in a 61 ± 13 Dobson unit reduction in total column ozone between late November 1999 and 5 March 2000 (the date of the last balloon-borne measurement considered here). This loss estimate is valid for the core of the vortex during the time period covered by the observations. It is shown that the observed changes in the O 3 versus N 2 O relation were almost entirely due to chemistry and could not have been caused by dynamics. The chemical loss of column ozone inferred from the balloon-borne measurements using the ''ozone versus tracer'' technique is shown to compare well with estimates of chemical loss found using both the Match technique (as applied to independent ozonesonde data) and the ''vortex-averaged descent'' technique (as applied to Polar Ozone and Aerosol Measurement (POAM) III satellite measurements of ozone). This comparison establishes the validity of each approach for estimating chemical loss of column ozone for the Arctic winter of 1999/2000.