Atmospheric Transport

Research on Atmospheric Transport

Transport of trace components of the Earth’s atmosphere, such as gases, smoke or dust, is governed by the winds and their turbulent properties. Simulating the transport and dispersion of such substances as realisticly as possible by means of atmospheric models is a persistent challenge due to the interaction of physical processes at very disparate scales. In-situ measurements and LIDAR observations from research aircraft are an increasingly powerful means to validate model simulations. Spaceborne remote-sensing observations place the aircraft measurements in a horizontally coherent perspective. This research aims at bringing together models and data from different sources to improve our understanding of atmospheric transport processes.

Evaluating Lagrangian and Eulerian model simulations in the Arctic
High latitude regions are notoriously difficult to simulate for atmospheric models. In part, this is because the polar regions are a harsh and inaccessible region and have remained so until present. In addition, however, the peculiar situation in these regions for example leads to very shallow and stably stratified boundary layers that are not well represented in models with limited vertical grid resolution. Remote sensing observations are hampered by the reflective ice and snow surfaces, and passive sensors are blind during a large part of the year because of the polar night. It is however known that the Arctic are a very sensitive region of the climate system, and at least the Arctic is a large sink for polluted air masses emitted from human activity in the mid-latitudes.

In our study, we investigated how a heavily polluted airmass originating from forest fires in Siberia was transported with a low-pressure system across the North Pole. Aircraft measurements and satellite observations indicated the horizontal and vertical extend of the pollution plume as it had risen to higher altitudes when arriving north of Greenland several days after emission. Comparison between two model simulations and measurements and observations showed very good agreement with the overall shape of the pollution feature. The Lagrangian transport model FLEXPART was however to retain more fine-scale structure and finer gradients than the Eulerian Chemical Transport Model (CTM) TOMCAT, in better agreement in particular with space-borne LIDAR observations and aircraft measurements.

Figure 1: Comparison of a FLEXPART model simulation (m) of total column carbon monoxide (CO) with satellite observations from the IASI satellite (n) and the TOMCAT Eulerian Chemistry Transport Model (CTM), panel (o).

Relevant publications

• Sodemann, H., Pommier, M., Arnold, S. R., Monks, S. A., Stebel, K., Burkhart, J. F., Hair, J. W., Diskin, G. S., Clerbaux, C., Coheur, P.-F., Hurtmans, D., Schlager, H., Blechschmidt, A.-M., Kristjánsson, J. E., and Stohl, A., 2011: Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations, Atmos. Chem. Phys., 11, 3631-3651. [PDF, 7.0MB, Interactive Discussion]
• Roiger, A., Schlager, H., Schäfler, A., Huntrieser, H., Scheibe, M., Aufmhoff, H., Cooper, O. R., Sodemann, H., Stohl, A., Burkhart, J., Lazzara, M., Schiller, C., Law, K. S., and Arnold, F., 2011: In-situ observation of Asian pollution transported into the Arctic lowermost stratosphere, Atmos. Chem. Phys., 11, 10975-10994 [PDF, 5.5MB, Interactive Discussion]
• Schmale, J., Schneider, J., Ancellet, G., Quennehen, B., Stohl, A., Sodemann, H., Burkhart, J., Hamburger, T., Arnold, S. R., Schwarzenboeck, A., Borrmann, S., and Law, K. S., 2011: Source identification and airborne chemical characterisation of aerosol pollution from long-range transport over Greenland during POLARCAT summer campaign 2008, Atmos. Chem. Phys., 11, 10097-10123 [PDF, 5.4MB, Interactive Discussion]
• Quennehen, B., Schwarzenboeck, A., Schmale, J., Schneider, J., Sodemann, H., Stohl, A., Ancellet, G., Crumeyrolle, S., and Law, K. S., 2011: Physical and chemical properties of pollution aerosol particles transported from North America to Greenland as measured during the POLARCAT summer campaign, Atmos. Chem. Phys., 11, 10947-10963 [PDF, 7.1MB, Interactive Discussion]
• Brock, C. A., Cozic, J., Bahreini, R., Froyd, K. D., Middlebrook, A. M., McComiskey, A., Brioude, J., Cooper, O. R., Stohl, A., Aikin, K. C., de Gouw, J. A., Fahey, D. W., Ferrare, R. A., Gao, R.-S., Gore, W., Holloway, J. S., Hübler, G., Jefferson, A., Lack, D. A., Lance, S., Moore, R. H., Murphy, D. M., Nenes, A., Novelli, P. C., Nowak, J. B., Ogren, J. A., Peischl, J., Pierce, R. B., Pilewskie, P., Quinn, P. K., Ryerson, T. B., Schmidt, K. S., Schwarz, J. P., Sodemann, H., Spackman, J. R., Stark, H., Thomson, D. S., Thornberry, T., Veres, P., Watts, L. A., Warneke, C., and Wollny, A. G., 2011: Characteristics, sources, and transport of aerosols measured in spring 2008 during the aerosol, radiation, and cloud processes affecting Arctic climate (ARCPAC) project, Atmos. Chem. Phys., 11, 2423-2453. [PDF, 12.7MB, Interactive Discussion]
• Hirdman, D., Burkhart, J. F., Sodemann, H., Eckhardt, S., Jefferson, A., Quinn, P. K., Sharma, S., Ström, S. and Stohl, A., 2010: Long-term trends of black carbon and sulphate aerosol in the Arctic: Changes in atmospheric transport and source region emissions, Atmos. Chem. Phys., 10, 9351-9368. [PDF, 4.3MB, Interactive Discussion]
• Hirdman, D., Sodemann, H., Eckhardt, S., Burkhart, J. F., Jefferson, A., Mefford, T., Quinn, P. K., Sharma, S., Ström, S. and Stohl, A., 2010: Source identification of short-lived air pollutants in the Arctic using statistical analysis of measurement data and particle dispersion model output, Atmos. Chem. Phys., 10, 669-693. [PDF, 12MB, Interactive Discussion]
• Warneke, C., Froyd, K. D., Brioude, J., Bahreini, R., Brock, C. A., Cozic, J., de Gouw, J. A., Fahey, D. W., Ferrare, R., Holloway, J. S., Middlebrook, A. M., Miller, L., Montzka, S., Schwarz, J. P., Sodemann, H., Spackman, J. R. and Stohl, A., 2010: An important contribution to springtime Arctic aerosol from biomass burning in Russia, Geophys. Res. Lett., 37, L01801, doi:10.1029/2009GL041816. [PDF]
• Stohl, A., and Sodemann, H., 2010: Characteristics of atmospheric transport into the Antarctic troposphere, J. Geophys. Res., 115, D02305, doi:10.1029/2009JD012536. [PDF (open access), 5.3MB]
• Hirdman, D., Aspmo, K., Burkhart, J. F., Eckhardt, S., Sodemann, H., and Stohl, A., 2009: Transport of mercury in the Arctic atmosphere: Evidence for a spring-time net sink and summer-time source, Geophys. Res. Lett., 36, L12814, doi:10.1029/2009GL038345. [PDF]