Method for determining types of precipitation in the atmosphere

• US 20060097907A1
• Filed: 02/02/2004
• Published: 05/11/2006
• Est. Priority Date: 02/07/2003
• Status: Active Grant

• Current Assignee: Metek GmbH
• Original Assignee: Metek GmbH
• Inventors: Fischer, Bernd, Peters, Gerhard
• Granted Patent: US 7,688,249 B2
• Time in Patent Office: Days
• US Class Current: 342/26.00R
• CPC Class Codes: G01S 13/951 ground based
• CPC Class Codes: G01S 13/958 Theoretical aspects
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

A method for determination of precipitation types in the atmosphere is described, wherein an output signal, in particular a radar signal, having a transmitting frequency spectrum is transmitted, reflection signals formed by reflection of the output signals at precipitation particles at at least two atmospheric levels and having a reflection spectrum are detected, and wherein finally the characteristics of the reflection signals are analyzed. The method according to the invention is characterized in that on analyzing characteristics of the reflection signals a course of a difference frequency spectrum formed by transmission frequency and reflection frequency spectrum is analyzed resolved by altitude levels.

Claims

1-20. -20. (canceled)

21. A method for determining types of precipitation in the atmosphere, including the steps of:

transmitting output signals, wherein said output signals have a transmitting frequency spectrum;

detecting reflection signals formed by scattering of said output signals at precipitation particles at at least two altitude levels, wherein said reflection signals have a reflection frequency spectrum; and

analyzing characteristics of said reflection signals, wherein during such analyzing step, a characteristic shape of a function curve of a difference frequency spectrum formed from said transmitting frequency spectrum and said reflection frequency spectrum is analyzed, resolved by altitude levels.

22. A method according to claim 21, wherein said output signals and said reflection signals are transmitted or received, respectively, by a combined transmitting and receiving unit.

23. A method according to claim 21, wherein a vertical dimension of 35 m is selected for said altitude levels.

24. A method according to claim 21, wherein said output signals and said reflection signals are transmitted or received, respectively, to or from, respectively, twenty-eight altitude levels.

25. A method according to claim 21, wherein a time span of 10 s is selected as a measurement time interval.

26. A method according to claim 21, wherein four altitude levels are used for analyzing said reflection signals.

27. A method according to claim 26, wherein the altitude levels 70 to 105 m, 105 to 140 m, 210 to 245 m, and 420 to 455 m are used or analyzing said reflection signals.

28. A method according to claim 21, wherein a course of the difference frequency spectrum is analyzed taking into consideration at least one parameter that is determined based on at least one of:

a maximum value of a receive power;

a value for a difference frequency at maximum intensity of said difference frequency spectrum;

a width of said difference frequency spectrum;

a quotient formed from a maximum value and a width of the difference frequency spectrum; and

a difference frequency between a maximum value and a value in the center of said difference frequency spectrum.

29. A method according to claim 28, wherein said at least one parameter is calculated and classified for said method for determining.

30. A method according to claim 21, wherein during said step of analyzing characteristics of said reflection signals, a precipitation event is assumed as soon as at least four values of said difference frequency spectrum of one altitude level are above an altitude level-specific threshold value.

31. A method according to claim 30, wherein said altitude level-specific threshold value is determined according to the specification “

average value of the difference frequency spectrum added to the 1.5 fold value of the standard deviation”

.

32. A method according to claim 21, wherein for determining a noise level, a maximum value of said difference frequency spectrum is determined, eliminated, and subsequently an average value of said difference frequency spectrum decreased by the eliminated maximum value is determined.

33. A method according to claim 32, wherein a minimum value of variance is determined for determining said noise level.

34. A method according to claim 21, wherein determined drop spectrums are used for determining a current Z/R relation.

35. A method according to claim 21, wherein 70 m is selected as a lowest measuring altitude.

36. A method according to claim 21, wherein a transmitting frequency of said output signal is modulated in a saw-tooth shaped manner.

37. A method according to claim 21, wherein said output signal is transmitted at a constant transmitting power.

38. An apparatus for determining types of precipitation in the atmosphere, comprising:

at least one transmitting unit for transmitting output signals having a transmitting frequency spectrum;

at least one receiving unit for receiving reflection signals formed by scattering of said output signals at precipitation particles in the atmosphere and having a reflection frequency spectrum, wherein said transmitting unit and said receiving unit are combined into a combination transmitting-receiving element such that a beam path covered by said output signal and said input signal is nearly identical; and

an analyzing unit for analyzing characteristics of said reflection signals taking into consideration a characteristic shape of a function curve of a difference frequency spectrum formed from said transmitting frequency spectrum and said reflection frequency spectrum, resolved by altitude levels.

39. An apparatus according to claim 38, wherein said combination transmitting-receiving element comprises a feedhorn as well as at least one parabolic mirror.

40. An apparatus according to claim 38, wherein a modulation generator is provided for modulating a transmission frequency of said output signal.