Apparatus and method for determining wind profiles and for predicting clear air turbulence

• US 6,000,285 A
• Filed: 05/22/1998
• Issued: 12/14/1999
• Est. Priority Date: 03/08/1996
• Status: Expired due to Fees

• Current Assignee: Alliedsignal Inc.
• Original Assignee: Alliedsignal Inc.
• Inventors: Leslie, Kenrick Rodford, Baker, Martin Carlin, Kilroy, Clint Patrick, Shand, Michael Lee, Barrett, Joseph J.
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US09/083,484
• Time in Patent Office: 571 Days
• Field of Search: 73/170.07, 73/170.08, 73/170.09, 73/170.11, 73/170.15, 73/178 R, 73/170.02
• US Class Current: 73/170.07
• CPC Class Codes: G01J 5/0014 for sensing the radiation from gases, flames
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01W 1/00 Meteorology
• CPC Class Codes: G01W 2001/003 Clear air turbulence detection or forecasting, e.g. for aircrafts

Abstract

The invention provides a system for passive measurement of atmospheric temperature using a passive direction detector for detecting the energy of a narrow wavelength band emanating from a volume of atmospheric gas. The resulting signal can be associated with an effective temperature. The effective temperature can be associated with an effective range. The system generates a temperature map which can determine, at predetermined time intervals, atmospheric temperatures in an azimuth plane associated with a predefined range from the detector. The temperature map can then be used to calculate temperature gradients that in turn can be used to compute the vertical wind vector difference and to determine the presence of clear air turbulence.

Claims

1. An apparatus for determining atmospheric conditions based on the calculation of the layered average Richardson number, Ri_L, comprising:

a) first temperature measurement means for measuring a plurality of temperatures at an altitude Z₁ ;

b) means, responsive to the first temperature measurement means, for calculating ∇

T, the vector temperature gradient, over the altitude Z₁ ;

c) wind shear computational means, responsive to the means for calculating the vector temperature gradient, for determining Δ

V/Δ

z, the vertical wind shear, where V is the horizontal wind vector;

d) second temperature measurement means for determining Δ

θ

/Δ

z, the vertical lapse rate of the potential temperature, where θ

is the potential temperature and z is the vertical direction; and

e) calculation means, responsive to the wind shear computational means and the second temperature measurement means, for calculating Ri_L using the equation;

##EQU5## where g is acceleration due to gravity.

2. The apparatus of claim 1 where the means for calculating the vector temperature gradient ∇

T comprises means for calculating a vector isobaric temperature gradient and the wind shear computational means comprises means for determining Δ

V/Δ

z according to the equation ##EQU6## where f is the Coriolis parameter resulting from the Earth'"'"'s rotation, T is the temperature at altitude Z₁, and k is the unit vector parallel to the local vertical.

3. The apparatus of claim 1 where the apparatus is positioned in an aircraft.

4. The apparatus of claim 1 where the apparatus is fixed to the ground.

5. The apparatus of claim 1 where the first temperature measurement means comprises a passive infrared detector.

6. The apparatus of claim 1 where the first temperature measurement means comprises means for determining the temperatures in a map at an effective range R_eff from the apparatus.

7. The apparatus of claim 1 where the first temperature measurement means comprises:

detector means for detecting radiation L(λ

) having a wavelength λ

from a predetermined direction; and

computational means, responsive to the detector means, for computing a value T_eff representing the temperature of the atmosphere at an effective range R_eff from the detector means.

8. The apparatus of claim 7 where the detector means comprises a passive infrared detector.

9. The apparatus of claim 8 where the detector means comprises means for detecting the emission of atmospheric CO₂ at the wavelength λ

from a portion of the atmosphere.

10. The apparatus of claim 8 where the wavelength λ

is between 12.2 μ

m and 13.0 μ

m.

11. The apparatus of claim 10 where the wavelength λ

is 12.3 μ

m.

12. The apparatus of claim 11 where the effective range R_eff is approximately 120 km.

13. The apparatus of claim 7 where the apparatus further comprises mapping means, responsive to the computational means, for mapping the temperatures T_eff along the predetermined direction.

14. The apparatus of claim 13 where the mapping means comprises means for generating the values T_eff at predetermined time intervals.

15. The apparatus of claim 13 where the mapping means comprises scanning means for varying the predetermined direction to generate a planar temperature map.

16. The apparatus of claim 15 where the scanning means comprises means for varying the predetermined direction vertically and the apparatus further comprises means for generating the temperature map for a plurality of altitudes.

17. The apparatus of claim 15 where the scanning means is geographically fixed and the temperature map represents isotherms at a predetermined altitude.

18. The apparatus of claim 17 where the predetermined altitude is a function of R_eff.

19. The apparatus of claim 15 where the scanning means is secured to an aircraft and comprises means for setting the predetermined direction in the azimuth plane.

20. The apparatus of claim 19 where the scanning means comprises means for varying the predetermined direction vertically and the apparatus further comprises means for generating a plurality of the horizontal temperature maps for a plurality of altitudes.

21. The apparatus of claim 17 where:

the wavelength λ

is between 12.2 μ

m and 13 μ

m;

the detector means comprises an infrared radiometer and scanning means for scanning the radiometer in the vertical and horizontal directions; and

the mapping means comprises means for generating horizontal and vertical temperature maps.

22. A method for determining atmospheric conditions based on the calculation of the layered average Richardson number, Ri_L, comprising the steps of:

a) measuring a plurality of temperatures at an altitude Z₁ ;

b) in response to the measurement of a plurality of temperatures, calculating ∇

T, the vector temperature gradient, over the altitude Z₁ ;

c) in response to the vector temperature gradient, determining Δ

V/Δ

z, the vertical wind shear, where V is the horizontal wind vector; and

d) determining Δ

θ

/Δ

z, the vertical lapse rate of the potential temperature, where θ

is the potential temperature and z is the vertical direction;

e) in response to the determination of vertical wind shear and vertical lapse rate of the potential temperature, calculating Ri_L using the equation;

##EQU7## where g is acceleration due to gravity.

23. The method of claim 22 where the step of calculating ∇

T comprises the step of calculating a vector isobaric temperature gradient and the step of determining wind shear comprises the step of generating the Δ

V/Δ

z signal according to the equation ##EQU8## where f is the Coriolis parameter resulting from the Earth'"'"'s rotation, T is the temperature at altitude Z₁, and k is the unit vector parallel to the local vertical.

24. The method of claim 22 where the steps are performed in an aircraft.

25. The method of claim 22 where the steps are performed on the ground.

26. The method of claim 22 where the step of measuring a plurality of temperatures at an altitude Z₁ comprises the step of measuring the temperature with a passive infrared detector.

27. The method of claim 22 where the step of measuring a plurality of temperatures at an altitude Z₁ comprises the step of determining the temperatures in a map at an effective range R_eff from the point of measurement.

28. The method of claim 22 where the step of measuring a plurality of temperatures at an altitude Z₁ comprises the steps of:

detecting radiation L(λ

) having a wavelength λ

from a predetermined direction; and

in response to the step of detecting radiation, computing a value T_eff representing the temperature of the atmosphere at an effective range R_eff from the point of detecting.

29. The method of claim 28 where the step of detecting comprises the step of detecting the radiation L(λ

) with a passive infrared detector.

30. The method of claim 29 where step of detecting the radiation L(λ

) comprises the step of detecting the emission of atmospheric CO₂ at the wavelength λ

from a portion of the atmosphere.

31. The method of claim 29 where the step of detecting radiation L(λ

) comprises the step of detecting radiation at wavelengths between 12.2 μ

m and 13.0 μ

m.

32. The method of claim 29 where the step of detecting radiation L(λ

) comprises the step of detecting radiation at a wavelength λ

of 12.3 μ

m.

33. The method of claim 32 where the step of computing a value T_eff comprises the step of computing T_eff at an effective range R_eff of approximately 120 km.

34. The method of claim 28 further comprising, in response to the step of computing the value T_eff, the step of mapping the temperatures T_eff along the predetermined direction.

35. The method of claim 34 where the step of mapping comprises the step of generating the values T_eff at predetermined time intervals.

36. The method of claim 34 where the step of mapping comprises the step of scanning for varying the predetermined direction to generate a planar temperature map.

37. The method of claim 36 where the step of scanning comprises steps of varying the predetermined direction vertically;

and the method further comprises the step of generating the temperature map for a plurality of altitudes.

38. The method of claim 36 where the step of scanning comprises the step of scanning from a geographically fixed point and the temperature map represents isotherms at a predetermined altitude.

39. The method of claim 38 where the predetermined altitude is a function of R_eff.

40. The method of claim 37 where the step of scanning comprises the steps of:

scanning from an aircraft; and

setting the predetermined direction in the azimuth plane.

41. The method of claim 40 where the step of scanning comprises the step of varying the predetermined direction vertically;

and the method further comprises the step of generating a plurality of the horizontal temperature maps for a plurality of altitudes.

42. The method of claim 36 where:

the wavelength λ

is between 12.2 μ

m and 13 μ

m and where the step of detecting comprises the step of scanning with an infrared radiometer in the vertical and horizontal directions; and

further comprising the step of generating horizontal and vertical temperature maps.