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Scanning Water Vapor DIAL Introduction (3) Measurements The water-vapor differential absorption lidar of University of Hohenheim (UHOH DIAL) is capable of performing full hemispherical scans based on the Coudé-concept. The 800-mm receiving telescope and a transmitter telescope are mounted on the scanning unit together with a safety radar. The transmitted laser beam is guided with an optical fiber to the transmitter telescope. The whole system is housed by a mobile platform in order to perform measurements at different field sites. The platform was specifically designed to fulfill the requirements of the sensitive optical and electronic parts of the DIAL equipment. (1) Overview of the UHOH DIAL Set Up References Behrendt, A., V. Wulfmeyer, A. Riede, G. Wagner, S. Pal, H. Bauer, M. Radlach, and F. Späth, 2009 In Richard H. Picard, Klaus Schäfer, Adolfo Comeron et al. (Eds.), SPIE Conference Proceeding Vol. 7475, Art. No. 74750L, DOI:10.1117/12.835143. Behrendt, A., S. Pal, F. Aoshima, M. Bender, A. Blyth, U. Corsmeier, J. Cuesta, G. Dick, M. Dorninger, C. Flamant, P. Di Girolamo, T. Gorgas, Y. Huang, N. Kalthoff, S. Khodayar, H. Mannstein, K. Träumner, A. Wieser, and V. Wulfmeyer, 2011: Observation of Convection Initiation Processes with a Suite of State-of-the-Art Research Instruments during COPS IOP8b. Q. J. R. Meteorol. Soc. 137(S1): 81–100, doi:10.1002/qj.758. Laser: Titanium:Sapphire laser, 820 nm, 250 Hz, max. 7 W (so far) pumped with Nd:YAG laser, 532 nm, 250 Hz, 41 W Injection seeded with DFB lasers Transmitter: 20-cm telescope, fiber-coupled Receiver: 80 cm primary mirror Resolution: 15 m, single shot = 1/250 s (raw data, analogue) Data products: Absolute humidity and backscatter signal at 820 nm Figure 2. DIAL technique Receiving Telescope Transmitting Telescope Camera Radar Sunlight Detectors Figure 3. Photograph of the scanning unit with the 200-mm transmitting and the 800-mm receiving telescopes. A safety radar is mounted next to the transmitting telescope. A camera can be used by the operator to observe the atmospheric volume which is sampled. Sunlight detectors protect the scanner from erroneous views too close to the Sun Figure 1. Overview of the UHOH DIAL set-up: The laser beam is guided with an optical fiber to the 200-mm transmission telescope (TM1- folding mirror, TM2-parabolic mirror). The receiver consists of a 800- mm primary telescope mirror (M1) and the secondary mirror M2. M3 to M7 are folding mirrors of the Coudé path. Beam reducers are used to focus the received light onto the detectors (BR1 to BR3a,b). IF- interference filter, BS-beam splitter, APD1, APD2-avalanche photodiodes. (2) Key Parameters Bhawar, R., et al., 2011: The Water Vapour Intercomparison Effort in the Framework of the Convective and Orographically-Induced Precipitation Study: Airborne-to-Ground-based and airborne-to-airborne Lidar Systems. Q. J. R. Meteorol. Soc. 137(S1): 225-347, doi:10.1002/qj.697. Wagner, G., A. Behrendt, V. Wulfmeyer, F. Späth, and M. Schiller, 2013: High-power Ti:sapphire laser at 820 nm for scanning ground-based water-vapor differential absorption lidar. Applied Optics, Vol. 52, Issue 11, pp. 2454-2469, http://dx.doi.org/10.1364/AO.52.002454. Andreas Behrendt, Florian Späth, Simon Metzendorf, Shravan Muppa, Andrea Riede, Volker Wulfmeyer University of Hohenheim, Institute of Physics and Meteorology, 70593 Stuttgart, Germany. Email: [email protected] Intensity of Lidar Signals Range r S on S off S on S off S on S off ln S on S off ln d dr 2 2 abs () Nr α σ = = Layer of H 2 O Number density () ( ) 0 exp Ir I r α = Beer‘s Law: S on (r) S off (r) ln d dr N(r) = 1 2 σ Absorption cross section HOPE quicklooks at https://www.uni-hohenheim.de/ipm_lidar/HOPE/UHOH_HOPE.htm 2 km Jülich FZJ Pier N DIAL

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Page 1: Scanning Water Vapor DIAL€¦ · Scanning Water Vapor DIAL Introduction (3) Measurements The water-vapor differential absorption lidar of University of Hohenheim (UHOH DIAL) is capable

Scanning Water Vapor DIAL

Introduction (3) MeasurementsThe water-vapor differential absorption lidar of University of Hohenheim (UHOH DIAL) is capable of performing full hemispherical scans based on the Coudé-concept.The 800-mm receiving telescope and a transmitter

telescope are mounted on the scanning unit together with a safety radar. The transmitted laser beam is guided with an optical fiber to the transmitter telescope. The whole system is housed by a mobile platform in

order to perform measurements at different field sites. The platform was specifically designed to fulfill the requirements of the sensitive optical and electronic parts of the DIAL equipment.

(1) Overview of the UHOH DIAL Set Up

References

Behrendt, A., V. Wulfmeyer, A. Riede, G. Wagner, S. Pal, H. Bauer, M. Radlach, and F. Späth, 2009 In Richard H. Picard, Klaus Schäfer, AdolfoComeron et al. (Eds.), SPIE Conference Proceeding Vol. 7475, Art. No. 74750L, DOI:10.1117/12.835143.

Behrendt, A., S. Pal, F. Aoshima, M. Bender, A. Blyth, U. Corsmeier, J. Cuesta, G. Dick, M. Dorninger, C. Flamant, P. Di Girolamo, T. Gorgas, Y.Huang, N. Kalthoff, S. Khodayar, H. Mannstein, K. Träumner, A. Wieser, and V. Wulfmeyer, 2011: Observation of Convection Initiation Processeswith a Suite of State-of-the-Art Research Instruments during COPS IOP8b. Q. J. R. Meteorol. Soc. 137(S1): 81–100, doi:10.1002/qj.758.

Laser: Titanium:Sapphire laser,820 nm, 250 Hz, max. 7 W (so far)pumped with Nd:YAG laser, 532 nm, 250 Hz, 41 WInjection seeded with DFB lasersTransmitter: 20-cm telescope, fiber-coupledReceiver: 80 cm primary mirrorResolution: 15 m, single shot = 1/250 s

(raw data, analogue)Data products: Absolute humidityandbackscatter signal at 820 nm

Figure 2. DIAL technique

ReceivingTelescope

TransmittingTelescope

Camera

Radar

SunlightDetectors

Figure 3. Photograph of the scanning unit with the 200-mm transmitting and the 800-mm receiving telescopes. A safety radar is mounted next to the transmitting telescope. A camera can be used by the operator to observe the atmospheric volume which is sampled. Sunlight detectors protect the scanner from erroneous views too close to the Sun

Figure 1. Overview of the UHOH DIAL set-up: The laser beam is guidedwith an optical fiber to the 200-mm transmission telescope (TM1-folding mirror, TM2-parabolic mirror). The receiver consists of a 800-mm primary telescope mirror (M1) and the secondary mirror M2. M3to M7 are folding mirrors of the Coudé path. Beam reducers are used tofocus the received light onto the detectors (BR1 to BR3a,b).IF- interference filter, BS-beam splitter, APD1, APD2-avalanche photodiodes.

(2) Key Parameters

Bhawar, R., et al., 2011: The Water Vapour Intercomparison Effort in the Framework of the Convective and Orographically-InducedPrecipitation Study: Airborne-to-Ground-based and airborne-to-airborne Lidar Systems. Q. J. R. Meteorol. Soc. 137(S1): 225-347,doi:10.1002/qj.697.

Wagner, G., A. Behrendt, V. Wulfmeyer, F. Späth, and M. Schiller, 2013: High-power Ti:sapphire laser at 820 nm for scanning ground-basedwater-vapor differential absorption lidar. Applied Optics, Vol. 52, Issue 11, pp. 2454-2469, http://dx.doi.org/10.1364/AO.52.002454.

Andreas Behrendt, Florian Späth, Simon Metzendorf, Shravan Muppa, Andrea Riede, Volker WulfmeyerUniversity of Hohenheim, Institute of Physics and Meteorology, 70593 Stuttgart, Germany. Email: [email protected]

Intensity of Lidar Signals

Range r

Son Soff

Son

Soff

Son

Soffln Son

Sofflnd

dr

2 2abs ( )N rα σ= =

Layer of H2O

Number density

( ) ( )0 expI r I rα= −Beer‘s Law:

Son(r)Soff(r)

lnddr

N(r) = 12 σ

Absorption cross section

HOPE quicklooks athttps://www.uni-hohenheim.de/ipm_lidar/HOPE/UHOH_HOPE.htm

2 km

Jülich

FZJ

Pier

N

DIAL