LIDAR Leblanc

NDACC and Water Vapor Raman Lidars: 

NDACC and Water Vapor Raman Lidars Thierry Leblanc JPL - Table Mountain Facility, CA leblanc@tmf.jpl.nasa.gov

NDACC and Water Vapor Raman Lidar 1. Measuring goals: 

NDACC and Water Vapor Raman Lidar 1. Measuring goals

NDACC and Water Vapor Raman Lidar 2. Existing wv lidars: 

NDACC and Water Vapor Raman Lidar 2. Existing wv lidars

NDACC and Water Vapor Raman Lidar: 3. Technique/retrieval: 

NDACC and Water Vapor Raman Lidar: 3. Technique/retrieval

NDACC and Water Vapor Raman Lidar: 4. Calibration: 

NDACC and Water Vapor Raman Lidar: 4. Calibration Calibration techniques: Internal/theoretical: Very challenging because requires accurate knowledge of transmission ratios of ALL the lidar optical and electro-photonic components  virtually impossible to achieve at required accuracy Semi-empirical: Use of a Calibration lamp to illuminate lidar receiver in conditions that mimic real measurements: Difficult, but possible  Accuracy depends mostly of lamp calibration accuracy External: Use of independent measurements, e.g., radiosonde, microwave  Easy to implement but accuracy limited by that of independent measurement

NDACC and Water Vapor Raman Lidar 5. CONCLUSION: 

NDACC and Water Vapor Raman Lidar 5. CONCLUSION

The Raman Lidar at Table Mountain Facility: Overview 1: 

The Raman Lidar at Table Mountain Facility: Overview 1 Laser energy: 700 mJ/pulse 8 channels: 3 w.v. ranges 3 telescopes: One 90 cm Three 6 cm Hamamatsu PMTs Licel photocounting 8000 7.5-m bins Vertical resolution 75-m

The Raman Lidar at Table Mountain Facility: Overview 2: 

The Raman Lidar at Table Mountain Facility: Overview 2 Calibration used so far: Radiosondes: Vaisala Humicap RS-92 sensors Future plans: UV lamp, GPS, Microwave Simultaneous, multiple calibration techniques Important requirement for NDACC long-term measurements: Stable calibration constant

The Raman Lidar at Table Mountain Facility: Overview 3: 

The Raman Lidar at Table Mountain Facility: Overview 3 TMF 50 miles NE of Los Angeles Lat: 34.4ºN Long: 117.7ºW Alt: 2285 m (7500 ft) > 340 clear nights/year Dataset TMF water vapor measurement program started in late 2004 November 2004 – Present: Radiosonde P,T, (2.3-20 km), RH (2.3-15 km) April 2005 – Present: Raman Lidar (4-19 km) Lidar vertical resolution and accuracy: 75 m instrumental, 2-h routine integration (5-minutes minimum) WV total error estimated to ~5-8 ppm at tropopause

The Raman Lidar at Table Mountain Facility: Overview 4: 

The Raman Lidar at Table Mountain Facility: Overview 4

The Raman Lidar at Table Mountain Facility: Overview 5: 

The Raman Lidar at Table Mountain Facility: Overview 5

The Raman Lidar at Table Mountain Facility: Overview 6: 

The Raman Lidar at Table Mountain Facility: Overview 6

The Raman Lidar at Table Mountain Facility: Overview 7: 

The Raman Lidar at Table Mountain Facility: Overview 7

The Raman Lidar at Table Mountain Facility: Overview 8: 

The Raman Lidar at Table Mountain Facility: Overview 8 Watch time variability!

Aura/MLS - Lidar andAura/MLS - sonde: 

Aura/MLS - Lidar and Aura/MLS - sonde The Raman Lidar at Table Mountain Facility: Overview 9

The Raman Lidar at Table Mountain Facility: Overview 10: 

The Raman Lidar at Table Mountain Facility: Overview 10

The Raman Lidar at Table Mountain Facility: Summary: 

The Raman Lidar at Table Mountain Facility: Summary So Far: TMF Water Vapor Raman Lidar is doing well Capable to reach 15-18 km for a 2-hour integration As of today, used only radiosonde for calibration Next: Introduce new calibration techniques: Lamp GPS? Microwave? Improve lidar power/aperture capability to reach final objectives of detection level of 2 ppm at 15 km

The Raman Lidar at Table Mountain Facility: Overview 1: 

6/13/2005 The Raman Lidar at Table Mountain Facility: Overview 1 6/13/2005 Red = JPL-AT Green = Sonde-AT Orange = STROZ-Lite – AT From: Tom McGee and Larry Twigg, NASA-GSFC

The GSFC Raman Lidars: Overview 2: 

The GSFC Raman Lidars: Overview 2 From: Tom McGee and Larry Twigg, NASA-GSFC