Layer Analysis in ARC-IONS John Merrill University of Rhode Island

1. Layer Analysis in ARC-IONSJohn MerrillUniversity of Rhode Island • Outline of new approaches to finding layers in sonde profiles and analyzing their occurrence. • Filtering, to produce an unperturbed profile, is avoided. • Instead a straightforward, if heuristic approach is used. • This is applied here to data from the Arc-IONS ozonesonde network.

2. Examples of unlayered and layered profiles shown. • The tropopuase and lowermost 2 km of the stratospheric are indicated. • Averaged MR in 100 m intervals, buth with appropriate choice of parameters the analysis can be applied to unsmoothed data.

3. Begin with a vertical line intersecting the profile. • Think of the line as the stile of a window, which is moved across the distribution in increments of the tolerance interval, ~ 7 ppb, say, creating a set of parallel lines. • Groups of three or more adjacent intersection points make up a putative layer edge, here marked with a crimson + sign. • A layer is defined to have edges with opposite slopes, with a limited separation between the edges at or near the peak.

4. Begin with a vertical line intersecting the profile. • Think of the line as the stile of a window, which is moved across the distribution in increments of the tolerance interval, ~ 7 ppb, say, creating a set of parallel lines. • Groups of three or more adjacent intersection points make up a putative layer edge, here marked with a crimson + sign. • A layer is defined to have edges with opposite gradient, with a limited separation between the edges at or near the peak.

5. The sign and magnitude of the gradients (of the edges) are shown to the right. • The extreme values for two tropospheric layers are shown. A lower stratospheric layer peak is off scale. • The search does not extend above the lowermost stratosphere. • The amplitude, thickness and mean vertical derivative are found simply.

6. It is acknowledged that the bump in the “unlayered” profile could be counted as a layer. Careful specification of what’s “Not A Layer” may suffice. • Vertical distributions will be plotted relative to the thermal (WMO) tropopuase.

7. Tropopuase-relative height vs. Amplitude (ozone mixing ratio increment) for westernmost sites.

8. Tropopuase-relative height vs. layer thickness for four interior sites.

9. Scatter plot of gradient vs. layer amplitude for easternmost sites.

10. Diminished layering noted at some sites. Note also reduced contrast betweeen the upper troposphere and lower stratosphere.

11. Weaker dominance of LS vs. UT layers is common at sites well east of the mountains. This begs compare/contrast with dynamical diganostics and/or LID characterization.

12. Modest response time of ECC cell may lead to underestimate of amplitude (extreme values).

13. Tropopause relative height vs. temporal variability of ozone mixing ratio. Layer occurrence a secondary factor (albeit underestimated?).

14. Event-specific geographical variation of layering is next target. Some relationships don’t require this (left), while others do (right).

15. ~ Finis ~

16. Acknowledgements • Support provided by NASA as part of the AURA Validation effort. • Kathryn George, an undergraduate at Slippery Rock U. supported over the summer by an NSF-sponsored site REU program. • Data provided by valued colleagues and carefully archived by J. Witte.