tmf

Table Mountain Facility, California

General

The NASA Jet Propulsion Laboratory (JPL) Table Mountain Facility (TMF) is a unique, remote scientific and engineering facility that provides an ideal location for many research projects, including astronomy, lidar, and projects for universities. TMF's remote location, altitude, climate, and lack of light contamination in the dark sky historically makes it one of the best places in the USA for cloudless night time skies, essential for atmospheric remote sensing. The JPL atmospheric lidar group has been designing, building and operating for over two decades several lidar instruments dedicated to the long term monitoring of atmospheric composition and satellite validation. The long-term high quality measurements from these lidars contribute to our understanding of our changing planet, in particular processes governing stratospheric ozone depletion and climate change.

See the JPL-TMF Lidar Group Website for more details.

Instrument Description

1. Stratospheric ozone DIAL:

A Differential Absorption Lidar (DIAL) has been routinely measuring stratospheric ozone (15-50 km), middle atmospheric temperature (25-90 km), and stratospheric aerosols (15-40 km) from TMF since 1988. The instrument acquired over 3000 ozone and temperature profiles. It has undergone three major upgrades in 1994, 2001, and 2016/2019. The current system combines Rayleigh/Mie and nitrogen vibrational Raman scattering techniques, and includes 12 receiving channels (6 channels operating at the ozone-absorbed wavelengths of 308 nm and 332 nm, and 6 channels at the non-absorbed wavelengths of 355 nm and 387 nm). The combination of its channels allows ozone retrievals between 8 km and 50 km altitude, temperature retrieval between 28 km and 90 km, and aerosol backscatter ratio between 12 km and 40 km.

Instrument/dataset characteristics:

  • Instrument vertical resolution: 300-m until 2019, 15-m since then
  • Vertical range: ozone=[12,50] km; Temperature=[12,90] km; Aerosols=[12,40] km
  • Instrument temporal resolution: Typically from 5-min to 2-hours
  • Typical measurement frequency: 3-5 times per week, nighttime only
  • Occasional "all-night" measurements for case studies and campaigns
  • Typical total number of measurements per year: 200.

2. Tropospheric ozone DIAL:

A tropospheric ozone lidar (4-25 km) also located at TMF has been operating since 1999. This DIAL system was designed in the early 1990s for the measurements of tropospheric ozone and aerosols. It was reconfigured and optimized in 1998 for tropospheric ozone exclusively. Routine data acquisition started in 1999 and the instrument has since measured over 2000 tropospheric ozone profiles. The system uses the Rayleigh/Mie scattering technique, and includes 4 receiving channels (2 channels operating at the ozone-absorbed wavelength of 289 nm and 2 channels at the weakly-absorbed wavelength of 299 nm). The tropospheric ozone DIAL pair 289/299 nm allows ozone retrievals between the altitudes of 4 km and 20 km. To extend the vertical range, the signal received from either the 308 or 355 nm (low-range) channel of the co-located stratospheric DIAL is used with the (upper range) 299 nm of the tropospheric ozone system to form a hybrid DIAL pair allowing ozone to be retrieve in the lower stratosphere (12-27 km).

Instrument/dataset characteristics:

  • Instrumental vertical resolution: 7.5 m
  • Vertical range: ozone=[3,25] km
  • Typical temporal resolution: From 5-min to 2-hours
  • Typical measurement frequency: 3-5 times per week, nighttime (routine), occasionally daytime (special events)
  • Occasional Up to several consecutve days (daytime and nighttime) for process studies and campaigns
  • Typical total number of measurements per year: 200.

3. Water Vapor Raman Lidar:

This Raman lidar, dedicated to the measurement of upper tropospheric water vapour, was first built in 2003. It was redesigned in 2005 and 2007 in order to optimize its detection capability in the Upper Troposphere/Lower Stratosphere (~5 ppmv). Routine data acquisition started in 2005 and the instrument has since measured over 500 tropospheric water vapour profiles. The system uses the vibrational Raman scattering of the nitrogen and water vapour molecules and includes 9 receiving channels (3 Rayleigh channels at 355 nm dedicated to temperature and aerosol measurements, 3 "nitrogen" channels at 387 nm, and 3 "water vapour" channels at 407 nm). After a few signal corrections, the ratio of the lidar signals at 407 nm and 387 nm is proportional to water vapour mixing ratio. The measurements are calibrated using a calibration lamp and routine RS92 radiosonde measurements. The combination of the various channels allows water vapour retrieval from 3.5 km to 15 km.

Instrument/dataset characteristics:

  • Instrumental vertical resolution: 7.5 m
  • Vertical range: water vapour=[3.5,15] km
  • Typical temporal resolution: From 5-min to 2-hours
  • Typical measurement frequency: 3-5 times per week, nighttime only
  • Occasional "all-night" measurements for case studies and campaigns
  • Typical total number of measurements per year: 200.

References

McDermid, S. M. Godin, and L. O. Lindquist, “Ground-based laser DIAL system for long-term measurements of stratospheric ozone,” Appl. Opt. 29, 3603–3612 (1990), https://doi.org/10.1364/AO.29.003603

McDermid, I. S., G. Beyerle, D. A. Haner, and T. Leblanc, "Redesign and improved performance of the tropospheric ozone lidar at the jet propulsion laboratory table mountain facility," Appl. Opt. 41, 7550-7555 (2002), https://doi.org/10.1364/AO.41.007550

Leblanc, T., McDermid, I. S., and Walsh, T. D.: Ground-based water vapor raman lidar measurements up to the upper troposphere and lower stratosphere for long-term monitoring, Atmos. Meas. Tech., 5, 17-36, 2012; https://doi.org/10.5194/amt-5-17-2012

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