After a successful testing period in 2009 (see earlier FGAM news item “Doppler lidar - successful test flights”), CalNex 2010 is now up and running (see http://www.esrl.noaa.gov/csd/lidar/calnex/ for more details).  The project, concerned with measuring air quality and climate change chemistry in California, utilises the FGAM Halo lidar fitted aboard the NOAA Twin Otter (and operated by Fay Davies) alongside the NOAA TOPAZ lidar.  When combined, the data from the two instruments can give a measure of ozone flux with the FGAM instrument providing radial velocity observations and the TOPAZ instrument providing ozone observations, as shown below.

The project is a large collaborative effort and brings together the NOAA WP-3D and Twin Otter Remote Sensing aircraft, and the R/V Atlantis ship platform as well as ground-based observation sites.

FGAM responds to Volcanic Ash Plume

FGAM Instrument Scientists are monitoring the atmosphere above the UK at the observatories and on the FAAM 146 aircraft in response to the recent volcanic ash episode which has been affecting the country.  Eruptions beneath the Eyjafjallajoekull Glacier in Iceland sent plumes of volcanic ash into the atmosphere and the winds associated with the high pressure system transported the plume toward the UK and Europe.

Continuous observations of the atmosphere above the UK using lidars at ground-based observatories are being made by FGAM Instrument Scientists to look for signs of the ash plume.  The FGAM Elight Ozone and Aerosol Lidar at the NERC MST radar facility in Capel Dewi, is in continuous operation (unless deployed in field work) measuring profiles of both ozone and aerosol.  An aerosol layer, thought to be volcanic ash, was observed on 16 April above the site at an altitude of approximately 1.7 km.  More data plots and further information can be found at the University of Manchester's Centre for Atmospheric Science webpages.

The FGAM Halo photonics lidar, in operation at the Salford Urban Built Environmental Research Base (SUBERB) in Salford, Greater Manchester, also observed signs of the ash layer.  The lidar laser light reflects from the small particles in the atmosphere and the back-scattered signal is measured by the lidar. Above the planetary boundary layer the air is much cleaner and the lidar usually only measures high intensity back-scattered signal from cloud particles, but during the episode the lidar measured what is thought to be the volcanic ash as a medium intensity return in this region of the atmosphere.

Ground-based observations of chemical species continue to be made at the Weybourne Atmospheric Observatory, North Norfolk, but no volcanic ash has been detected so far. 

Important observations of the larger ash particles were made with FGAM instruments by FGAM Instrument Scientists on the FAAM 146 aircraft.  Airborne observations have also been made aboard the ARSF Dornier 228 aircraft and FGAM instrument scientists are involved in the analysis.

FGAM are working on data collection and analysis with the Met Office who are coordinating monitoring activities to provide up-to-date information about the transport and dispersal of the plume.  Further information about the Met Office efforts can be found on their webpages.

The FGAM Doppler lidar instrument has been successfully installed aboard the NOAA twin otter aircraft by Fay Davies. The instrument was involved in a successful mission around Colorado producing very nice data from the air (4km to the ground) and showed good agreement with a similar ground-based instrument.  A brief report about the study is available here 

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