Using GOES total column ozone to diagnose stratospheric intrusions and nowcast non-convective cyclone windstorms: Methodology and initial results

In this presentation, we discuss the development of the GOES total ozone derived product and show initial results of the application of this project to the problem of forecasting non-convective windstorms associated with intense mid-latitude cyclones.

Mesoscale “tropopause fold/stratospheric intrusion” features associated with intense cyclones have long been identified in upper-tropospheric analyses (Browning 1997), but their connections to near-surface conditions are yet to be fully understood. For example, some stratospheric intrusions are able to convey ozone and strikingly low relative humidities all the way to the surface in the absence of intense near-surface dynamical features (Lamb 1977; see also http://cimss.ssec.wisc.edu/goes/misc/990329.html). Other episodes are associated with some, but not all, intense cyclones. Comparatively little research appears to have been devoted to relating the mesoscale folds/intrusions to vertical motion fields.

The relationship between downward vertical motion and mesoscale folds/intrusions appears to be of critical importance in understanding non-convective cyclone-generated windstorms, such as occurred across the upper Midwest on 10 November 1998 (Iacopelli and Knox 2001). Ten deaths, 34 injuries and at least $40 million in damage occurred in connection with winds in a record-setting mid-latitude cyclone, with the most intense winds (60-81 kts) developing behind the center of the low along a path from La Crosse to Wausau, WI. These winds were associated with a significant tropopause fold whose prominent ozone signature was captured by the then-new GOES Sounder Ozone imagery (Li et al. 2001). Close inspection of GOES water vapor revealed a mesoscale “hook” of dry air, a lobe of the intrusion, that was dynamically wrapped around the cyclone's mid- to upper-tropospheric circulation. This hook was closely correlated in both space and time with surface “storm reports” from the National Weather Service (Iacopelli and Knox 2001), suggesting that in at least some cases this feature could be used for pinpoint nowcasting purposes.

The dynamical features of interest for nowcasting these events are on scales of tens of kilometers, evolve rapidly on the timescales of hours, and are located generally in the upper troposphere. As a result, the most promising GOES products for this approach appear to be the GOES Imager water vapor channel and the GOES Sounder total ozone derived product.

In the work presented here, we discuss our development of the GOES total ozone product and its use in diagnosing a stratospheric intrusion in a damaging non-convective windstorm across Wisconsin in November 2003 (see figure). The initial 3x3 FOV of the total ozone product (implied horizontal resolution of 30 km) has been improved to 1x1 FOV (10-km resolution), providing unprecedented mesoscale detail for ozone features associated with cyclones. The November 2003 event, which caused $26.5 million in damage and 76-kt wind gusts, provides an excellent testbed for analyzing the performance of the GOES total ozone product and its ability to provide insight into the mesoscale structure of the storm. It is the goal of this project that such insight could, in turn, benefit the forecasting community by leading to more accurate wind forecasts during these non-convective wind events.

References

Browning, K.A., 1997: The dry intrusion perspective of extratropical cyclone development. Meteorol. Appl., 4, 317-324.

Iacopelli, A.J., and J.A. Knox, 2001: Mesoscale dynamics of the record-breaking 10 November 1998 mid-latitude cyclone: A satellite-based case study. Natl. Wea. Dig., 25 (1,2), 33-42.

Lamb, R.G., 1977: A case study of stratospheric ozone affecting ground-level oxidant concentrations. J. Appl. Meteor., 16, 780-794.

Li, J., C.C. Schmidt, J.P. Nelson, T.J. Schmit, and W.P. Menzel, 2001: Estimation of total atmospheric ozone from GOES sounder radiances with high temporal resolution, Journal of Atmospheric and Oceanic Technology, 18, 157-168.