MIMOSA PV

The isentropic wind fields from the T106-truncated operational European Centre for Medium Forecast Range (ECMWF) analysis are used (1.125º x 1.125º coarse-grid resolution) to run MIMOSA in a "PV analysis" mode.

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Figure 1

The ECMWF data are made available at the Norwegian Institue for Air Research (NILU) to all the Network for the Detection of Atmospheric Composition Change (NDACC) investigators. The model outputs at 6-h intervals are interpolated onto fifty-five isentropic levels from 300 K to 2000 K before being fed to the high resolution PV advection model.

To study Rossby wave breaking events near the tropopause, and the long-term evolution of (high-resolution) equivalent latitude at MLO and TMF, MIMOSA has been running non-stop at JPL in this mode since 1999, and has since been producing 4-times daily global high-resolution isentropic PV fields in near-real time (dataset up-to-date every 10 days). Two examples of research application are shown below.

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Figure 2

Figure 1 is the time evolution (every 6-hour) in mid-March 2004 of a lower strtatospheric polar filament (at 435 K) transported southward towards the Hawaiian Islands (a very rare event).

Figure 2 illustrates how rare polar filaments are actually observed abovbe Hawaii. The figure shows 2D color contour plots of meridional gradient of PV (in equivalent latitude coordinates) at 435 K for 4 successive northern hemisphere winters. The regions of stronger gradients (i.e., yellow and red) represent meridional transport barriers. The visualization of barriers at high laitutdes is enhanced using a solid black curves, and represent the northern and southern vortex edges. The superimposed white solid curves represent equivalent latitude at Mauna Loa Observaory, Hawaii. The polar filament shown on figure 1 is materialized here by the white curve (MLO equiasvlent laitutde) intersecting the black curve (polar vortex edge) in mid-March 2005. This event does not occur at any other time.

 

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Figure 3

The second example (figure 3) is the time evolution of a tropopause folding caused by the stretching and breaking of Rossby waves. This type of stretching often cause thin layers of increased ozone (ozone-rich stratospheric air) to enter the mid-latitudes and low-latitudes upper tropopshere (poor in ozone). Exchange of airmasses of different characteristics across the tropopause is can be irreversible, and is often identified in midlatitudes as the so-called "stratospheric intrusions".

References

Hauchecorne, A., S. Godin, M. Marchand, B. Heese, and C. Souprayen (2002), Quantification of the transport of chemical constituents from the polar vortex to midlatitudes in the lower stratosphere using the high-resolution advection model MIMOSA and effective diffusivity, J. Geophys. Res., 107 (D20), 8289, doi: 10.1029/2001JD000491.

Leblanc, T., I. S. McDermid, and A. Hauchecorne, A study of ozone variability and its connection with meridional transport in the Northern Pacific lower stratosphere during summer 2002, J. Geophysical Research, 109, D11105, doi:10.1029/2003JD004027, 2004

Leblanc, T., O. P. Tripathi, I. S. McDermid, L. Froidevaux, N. J. Livesey, W. G. Read, and J. W. Waters (2006), Simultaneous lidar and EOS MLS measurements, and modeling, of a rare polar ozone filament event over Mauna Loa Observatory, Hawaii, Geophys. Res. Lett., 33, L16801, doi:10.1029/2006GL026257.

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