Berechnung von Temperaturen aus Lidar-Daten Michael Gerding Leibniz-Institut für Atmosphärenphysik

LIDAR: LIght Detection and Ranging

Elastic Lidar Backscatter Signal M. Gerding, PhD thesis, IAP Kühlungsborn, 2000

Basic Lidar Equation intensity at the emitted wavelength received from altitude z i (z=c·t/2) emitted intensity at the wavelength solid angle of visible telescope aperture transmission between ground and scattering altitude z i detector sensitivity total backscatter coefficient geometric overlap between laser and telescope FOV background bin width

Temperature profiles by combined lidars Alpers et al., ACP, February 2003, 0:30 - 1:30 UT IAP Kühlungsborn (54°N, 12°E)

Light Interaction with the Atmosphere Rayleigh scattering elastic; atoms or molecules Mie (particle) scattering elastic; aerosol particles Raman scattering inelastic, molecules Fluorescence inelastic, broadband emission; atoms or molecules Resonance fluorescence elastic at atomic transition; large cross section Absorption attenuation in bands; molecules or particles

above 80 km: K resonance lidar Hyperfinestructure and Doppler broadening of a K resonance line von Zahn and Höffner, 1996

km: K resonance lidar Hyperfinestructure and Doppler broadening of a K resonance line Measured and fitted shape of the resonance line

22-90 km: Rayleigh lidar hydrostatic equation ideal gas law relative density profile required - derived from (aerosol free) lidar backscatter signal

Temperature profile from air density profile temperature air density

1-30 km: Rotation-Raman lidar Rotation-Raman spectrum of air for excitation at nm Alpers et al., 2004

Light Interactions with the Atmosphere from: A. Behrendt, PhD thesis, University Hamburg, 2000 Rayleigh-Raman spectrum wavelength [nm] relative intensity Q branch total intensity of the rotational Raman bands Rayleigh/Mie line pure rotation Raman bands vibrational Raman scatter

Temperature Profile from Rot. Raman Lidar Rotation-Raman spectrum depends on temperature Intensity of transitions to high J-numbers increase with temperature, intensity of transitions to low J-numbers decrease Intensity ratio between two different wavelengths depends on temperature For lidar choose narrow fractions of the spectrum wavelength [nm] high-J filter low-J filter A. Behrendt, Uni Hamburg, 2000

Temperature Profile from Rot. Raman Lidar (II) Backscatter signal at the different wavelengths depend on temperature, but also on the filter characteristic, the transmission of the detection system, atmospheric extinction  temperature dependence of the signal can (hardly) be calculated or  lidar can be calibrated with respect to temperature response (comparison with other methods like radiosondes)

Comparison of temperature sounding principles rangecomplexitylimits Rayleigh-IntegrationStrato- and Mesosphere aerosol inhibits sounding hydrostatic equilibrium assumed Raman-Integration(Troposphere) Stratosphere aerosol disturbs sounding hydrostatic equilibrium assumed Resonance-DopplerMesopause region ( km)  limited to atomic metal layer Brilloiun-Dopplerlower troposphere  very weak signal hydrostatic equilibrium assumed Rotation-RamanTropo- and Stratosphere  weak signal

Temperature profiles by combined lidars

GW propagation from troposphere to MLT

Lidar-observed temperature variations

IAP Mobile Potassium Lidar photo: J. Höffner Potassium Temperature Lidar of Leibniz-Institute of Atmospheric Physics on the Plateauberget near Longyearbyen (78°N, 16°E)

Lidar telescope hall at IAP Kühlungsborn

Laser beams of IAP resonance/Rayleigh lidars at night

IAP main building with operating lidar

Detector of the IAP T lidars originally described by Alpers et al. [2004]