mlo

Mauna Loa Observatory

General

Mauna Loa Observatory (MLO) is a premier atmospheric research facility that has been continuously monitoring and collecting data related to atmospheric change since the 1950s. The undisturbed air, remote location, and minimal influences of vegetation and human activity at MLO are ideal for monitoring consituents in the atmosphere that can cause climate change. The observatory is part of the National Oceanic and Atmospheric Administration (NOAA) - Earth System Research Laboratory (ESRL) - Global Monitoring Division (GMD). Two NDACC lidars are operated at MLO. One system is operated by NOAA/ESRL and is dedicated to the measurement of stratospheric aerosols and tropospheric water vapour. The other system is operated by NASA/JPL and is dedicated to the measurement of stratospheric ozone, temperature and aerosols.

Instrument Description

The NOAA system, a Rayleigh/Raman lidar, used a Ruby laser (694-nm) between 1974 and 1998, and a Nd:YAG laser (532, 1064 nm wavelengths) since 1994. It is dedicated to the measurement of stratospheric aerosols (20-40 km). A recent upgrade allows for the measurement of water vapour up to an altitude of 10-12 km.

Instrument/dataset characteristics:

  • Instrumental vertical resolution: 300 m
  • Vertical range: aerosols=[20,40] km; water vapour=[4,10] km
  • Typical temporal resolution: from 3 min to 4 hours
  • Typical measurement frequency: once a week, nighttime only
  • Typical total number of measurements per year: 50

The NASA system, a Differential Absorption Lidar (DIAL) is the second instrument built by the JPL atmospheric lidar group group. Routine data acquisition started in July 1993 and the instrument has since measured over 2500 stratospheric ozone, aerosol, and atmospheric temperature profiles. It underwent a major upgrade in 2001. The system combines Rayleigh/Mie and nitrogen vibrational Raman scattering techniques, and includes 8 receiving channels (3 channels operating at the ozone-absorbed wavelengths of 308 nm and 332 nm, and 5 channels at the non-absorbed wavelengths of 355 nm and 387 nm). The combination of its channels allows ozone retrieval between the altitudes of 12 km and 50 km, temperature retrieval between 12 km and 95 km, and aerosol backscatter ratio between 12 km and 50 km.

Instrument/dataset characteristics:

  • Instrumental vertical resolution: 300 m
  • Vertical range: ozone=[12,50] km; temperature=[12,90] km; aerosols=[12,40] 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 special studies
  • Typical total number of measurements per year: 200

References

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