5.32 Estimating regions of tropopause folding and clear-air turbulence with the GOES water vapor channel

Tony Wimmers, Wayne FeltzCooperative Institute for Meteorological Satellite Studies (CIMSS), UW-Madison

World Weather Research Symposium on Nowcasting and Very Short Range ForecastingToulouse, France, 5-9 Sept, 2005

141210864150200300400500600700(~100 km)subtropicalair masspolar air massstratospherePressure (hPa)Height (km)tropopauseCAT and tropopause foldsUpper-air frontAbstract: Clear-air turbulence remains a significant aviation hazard, yet by its nature it is very difficult to detect. One of the sources of clear-air turbulence is the dynamic instability associated with tropopause folding, which describes the entrainment of stratospheric air into tropospheric levels at upper-level fronts. We describe a near real-time satellite product that estimates areas of tropopause folding in regions of strong humidity gradients in the GOES midwave infrared (water vapor) channel. Using an empirical relationship between upper tropospheric humidity gradients and tropopause breaks, the algorithm estimates that turbulence-generating tropopause folds protrude from some of these tropopause breaks. This product is validated over the United States with manual pilot reports as well as newer automated aircraft reports of turbulence.

Vertical component of the fold

Web product: Real-time pirep validation Pirep data is provided courtesy of NCAR Aviation Digital Data Service (ADDS)

Web product: Real-time TAMDAR validation TAMDAR (Tropospheric Airborne Meteorological Data Report) is part of the Great Lakes Field Experiment Unfortunately, it is mostly lower and midtroposphere

http://cimss.ssec.wisc.edu/asap/exper/tfoldsVer2/pirepSep.htmlhttp://cimss.ssec.wisc.edu/asap/exper/tfoldsVer2/tamdarDisplay.html

Web pages:

April 8-30, 2005 1500-2300 UTC (peak time) Eastern U.S. (away from mountain wave turbulence) Above 15,000 feet (mid- and upper troposphere) Areas of strong convection are filtered out (no C.A.T.) If the pirep is in a modeled fold and reports turbulence, then this is a correctly classified Yes report. If the pirep is outside a modeled fold and reports no turbulence, this is a correctly classified No report. 2,293 pirep observations, 62% of ALL observations are turbulent.Validation: Details

Find the models Probability of Detection for turbulence Next, search for any further constraints on the model that improve the Probability of DetectionValidation: Method

* Does not purport to classify all negative reportsStatistics for tropopause fold turbulence prediction (N=2293, background rate of success=0.64)

Number of Yes reportsProportion of Yes reports correctly classifiedProportion of No reports mis-classified*

1. Initial model2960.770.632. Revised model: Longer folds2400.780.633. Revised model (#2): Longer folds, higher gradients1380.820.63

The tropopause folding model shows significant skill at predicting upper-tropospheric turbulence The model increases in accuracy significantly as it is made more selective (Prob of Detection = 82%) Predicted turbulence is predominantly light or moderatePreliminary conclusions: Trop folding + CATsubtropicalair masspolar air massstratosphereUpper-air front

My title and objective is

Saves lives, prevents damage and injury for anyone who gets on a plane. Basically, theres a lot of time and money that goes into this kind of safety.

The tie-in to multispectral will be evident later

Those of you who do midwave IR water vapor applications should be particularly interested in this. The rest of you, I dont know.Although this graph shows the chemical mixing, it was coincident with CATSo we need a tool to estimate tropopause heightMajor issues for multispectral sounding: What position do we assign to the fold? Can we obtain a tropopause height? Can we make out multiple layers? ***Notes:This latest version, which uses RUC grids to assign a height to the folds, was completed last Friday.The base image is the specific humidity product blue and purple are dry, polar subsiding air, yellow and orange are moist, subtropical air, and convectionGray are the foldsTurbulent pireps are red, non-turbulent pireps are in blueRed dots increase in size with the severity of the turbulenceLabels are in hundreds of feet, but reports that are in, above or below the folds show the difference in potential temperature between the pirep and the fold

Notes:

Now, I only have conclusions I can draw from an inspection of the performance of the model so far, but since were just here to share ideas, why dont I jump the gun and run these by you, and take questions anyway?Now, I only have conclusions I can draw from an inspection of the performance of the model so far, but since were just here to share ideas, why dont I jump the gun and run these by you, and take questions anyway?Now, I only have conclusions I can draw from an inspection of the performance of the model so far, but since were just here to share ideas, why dont I jump the gun and run these by you, and take questions anyway?