Atmospheric transport models

Assessing the spatial distribution of NHj emissions is of particular interest because of the link with ecological impacts of nitrogen deposition. Using statistical atmospheric transport models, such emission maps may be used to... 

Hunt, E. R. Jr., Piper, S. C., Nemani, R., Keeling, C. D., Otto, R. D. and Running, S. W. (1996). Global net carbon exchange and intra-annual atmospheric CO2 concentrations predicted by an ecosystem process model and three-dimensional atmospheric transport model. Global Biogeochem. Cycles 10, 431-456. 

Tans, P. P., Conway, T. J. and Nakazawa, T. (1989). Latitudinal distribution of the sources and sinks of atmospheric carbon dioxide derived from surface observations and an atmospheric transport model, /. Geophys. Res. 94, 5151-5172. 

Taylor, J. A. (1989). A stochastic Lagrangian atmospheric transport model to determine global CO2 sources and sinks - a preliminary discussion, Tellus, Ser. B, 41,272-285. 

Bouwman, A. F., and J. A. Taylor, Testing High-Resolution Nitrous Oxide Emission Estimates against Observations Using an Atmospheric Transport Model, Global Biogeochem. Cycles, 10, 307-318 (1996). 

Krey, P. W. Krajewski, B. 1970. Comparison of atmospheric transport model calculations with observation of radioactive debris. Journal of Geophysical Research, 75, 2901-2908. 

Jacob, D.J., el al., 1997 Evaluation and intercomparison of global atmospheric transport models using mRn and other short-lived traceis. J. Geophys. Res., 102,5953-5970. 

Transport and dispersion was evaluated without any form of tuning by comparing a simulation of the ETEX-1 release to the official measurements of surface concentration. To facilitate comparisons with models evaluated during ATMES 11 (Atmospheric Transport Model Evaluation Study) an identical statistical methodology was employed (Mosca et al. 1998). Background values were subtracted so that only the pure tracer concentration was used. Measurements of zero concentration (concentrations below the background level) were included in time series to the extent that they lay between two non-zero measurements or within two before or two after a non-zero measurement. Hereby, spurious correlations between predicted and measured zero-values far away from the plume track are reduced. 

To evaluate the deposition routines a simulation of the Chernobyl accident was carried out and compared to measurements of total deposited Cesium 137 (Cs-137). The measurements were extracted from the Radioactivity Environmental Monitoring database at the Joint Research Centre, Ispra, Italy (http //rem.jrc.cec.eu.int/). The comparison date was chosen to be 1 May 1986 at 12 00 UTC, since at this time the greatest number of measurements was available. Statistical measures were calculated following the recommendations of the Atmospheric Transport Model Evaluation Study (ATMES) final report (Klug et al. 1992). 

Robertson L, Langner J, Engardt M (1998) An Eulerian limited-area atmospheric transport model. J Appl Meteorol 38 190-210... 

The Governing Equations. Having a simplified chemical scheme, we will now incorporate it in an atmospheric transport model. We have looked for approximations appropriate to air basins subject to photochemical pollution. Because of the severity of the problem and the availability of data, the Los Angeles basin area serves as the object of model qualification studies. 

Figure 6 Terrestrial and oceanic sources and sinks of carbon inferred from inverse calculations with an atmospheric transport model and spatial and temporal variations in CO2 concentrations. The net fluxes inferred over each region have been averaged into 7.5°-wide latitude strips (Ciais et al., 2000) (reproduced by permission of the Ecological Society of America from Bcol. Appl, 2000, 10, 1574-1589).

CO2 to distinguish oceanic from terrestrial fluxes, have been carried out by several groups since 1990. An intercomparison of 16 atmospheric transport models (the TransCom 3 project) by Gurney et al. (2002) suggests average oceanic and terrestrial sinks of 1.3 PgC yr and 1.4PgCyr, respectively, for the period 1992-1996. 

FIGURE 3 Amplitude of the seasonal signal in the lower planetary boundary layer (at approximately 380 m above the surface) generated by the terrestrial biosphere in the CO2 mixing ratio (lower panel) and by oceanic exchanges in the atmospheric Oi/N, ratio (upper panel) as simulated with the TM3 atmospheric transport model. See text for the model setup description. 

FIGURE 3 Comparison between the observed seasonal cycle of COi and the simulated seasonal cycle produced by coupling the monthly estimates of net ecosystem production estimated by the Century model and fossil fuel emissions with the Hamburg ocean and atmospheric transport models for each of the seven high-latitude monitoring stations. The first six months of each cycle are displayed twice to reveal the annual variation more clearly. Mean and standard deviation are shown for the observed data (McGuire et iiL, 2000). 

All the problems encountered during application of the algorithms presented above illustrate the difficulty of solution of the advection problem in atmospheric transport models. A number of techniques have been developed to treat advection accurately, including flux-corrected transport (FCT) algorithms (Boris and Book, 1973), spectral and finite element methods [for reviews, see Oran and Boris (1987), Rood (1987), and Dabdub and Seinfeld (1994). Bott (1989, 1992), Prather (1986), Yamartino (1992), Park and Liggett (1991), and others have developed schemes specifically for atmospheric transport models. 

All of the problems encountered during application of the above algorithms illustrate the difficulty of solution of the advection problem in atmospheric transport models. A number of techniques have been developed to treat advection accurately including flux corrected transport (FCT) algorithms (Boris and Book, 1973), spectral and finite element... 

The sample should be processed quickly because of the short half-life of 135Xe (9.10 h) compared to133 Xe (5.234 d). The ARSA performs three sample analyses per day. The fair match of this frequency to the resolving time (6 h) of meteorological measurements made worldwide facilitates coordination with atmospheric transport models. The rapid analysis capability allowed the measurement of 135Xe in the Earth s atmosphere, see Fig. 15.9 (Bowyer et al., 1999). 

In this component of the subproject, OH + VOC rate constants have been measured and oxidation mechanisms developed. In addition, work is continuing on the reduction of the mechanisms, so that they can be more feasibly incorporated in atmospheric transport models. 

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