EP0488004A2
Expired / Lapsed
EP
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Microwave temperature profiler for clear air turbulance prediction
Assignee: National Aeronautics and Space Administration
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Filing: 1991-11-18
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Granted: —
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Expires: 2011-11-18
Abstract
Abstract A method for determining Richardson Number, Ri, or its reciprocal, RRi, for clear air prediction using measured potential temperature and determining the vertical gradient of potential temperature, dϑ/dz. Wind vector from the aircraft's instrumentation versus potential temperature dW/dϑ is determined and multiplied by dϑ/dz to obtain dW/dz. Richardson Number or its reciprocal is then determined from the relationship Ri = k [ dϑ dz + ( dW dz )²] for use in detecting a trend toward a threshold value for the purpose of predicting clear air turbulence. Other equations for this basic relationship are disclosed together with the combination of other atmospheric observables using multiple regression techniques.
Inventors
- 👤 Bruce L. Gary
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 01:37
CPC Classifications
G; G01; G01W; G01W1/00; G01W1/08; G01W2001/003
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
116 words
A method for determining Richardson Number, Ri, or its reciprocal, RRi, for clear air turbulence prediction aboard an aircraft in flight comprising the steps of determining vertical gradient of potential temperature, dϑ/dz, determining the correlation of wind vector from said aircraft's instrumentation versus potential temperature, dW/dϑ, multiplying the gradient of potential temperature with altitude, dϑ/dz, by said gradient of wind vector with potential temperature, dW/dϑ, to obtain vertical wind shear, dW/dz, and calculating Richardson Number, Ri, from said vertical gradients from an equation Ri = k [ dϑ dz + ( dW dz )²] or its reciprocal, RRi, for use in detecting a trend toward a threshold value for the purpose of predicting clear air turbulence.
Claim 2
Dependent Claim
94 words
A method as defined by claim 1 wherein said vertical gradient of potential temperature, dϑ/dz, is determined by measuring brightness temperature with a passive microwave radiometer operating at a frequency where oxygen molecules emit thermal radiation and scanning said radiometer through selected elevation angles above and below the flight line of said aircraft, and converting measured brightness temperature versus elevation angle to air temperature, T, versus altitude, z, and then converting said profiles of air temperature to profiles of potential temperature, ϑ, and from said profiles deriving said vertical gradient of potential temperature dϑ/dz.
Claim 3
Dependent Claim
68 words
A method as defined in claim 2 wherein determining the correlation of wind vector from said aircraft's instrumentation versus potential temperature, dW/dϑ, is accomplished by determining the slope of both the east-west and north-south wind components, U and V, versus potential temperature ϑ to obtain dU/dϑ and dV/dϑ and computing the orthogonal sum [(dU/dϑ)² + (dV/dϑ)²] 1/2 to obtain the gradient of wind vector with potential temperature, dW/dϑ.
Claim 4
Dependent Claim
53 words
A method for enhancing the quality of dW/dϑ in claim 3 by reducing the influence of horizontal gradients of wind on the dW/dϑ solution by performing a simultaneous regression of wind vector components U and V against both ϑ and time, so that the time correlation has minimum influence on the ϑ correlation.
Claim 5
Dependent Claim
79 words
A method as defined in claim 1 wherein Richardson Number, Ri, is the parameter of clear air turbulence prediction when the trend of Ri extends toward the critical region of 1 to 1/4 from the normal range of 5 to 100 or the reciprocal Richardson Number, RRi, is determined as the parameter of clear air turbulence prediction when the trend of RRi extends toward the critical region of 1 to 4 from the normal range of 0.01 to 0.2.
Claim 6
Dependent Claim
68 words
A method as defined in claim 5 wherein the severity of the clear air turbulence predicted is determined by evaluation of (dW/dz)² calculated for the extrapolated situation of RRi = 4, which is to say that the value of (dW/dz)² when RRi = 4 can be calculated from the values of dϑ/dz and dW/dz during the time that RRi is trending toward the critical region 1 to 4.
Claim 7
Independent Claim
58 words
A method for combining many atmospheric observables using multiple regression techniques to make predictions of near-future CAT likelihoods, in which Richardson Number, Ri, or its reciprocal, RRi, and the trend of the selected one is a crucial input observable, wherein each atmospheric observable available is multiplied by pre-calculated retrieval coefficients to yield the desired prediction of CAT likelihood.
References Cited (Backward Citations)
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