Lidar difficulties retrievals and successes Franco Marenco Crown

Lidar difficulties, retrievals, and successes Franco Marenco © Crown copyright Met Office

The 146 lidar story • • • • Mevex (2009) – first use – qualitative Laser frozen – six months for servicing First version of on-board viewer (Lidardisplay) Volcanic ash (2010) – quantitative – fully analysed FENNEC (Apr+May 2011) – quantitative data analysis planned Sept 2011 – loss of power – 4 months servicing DIAMET (Nov-Dec 2011) – Manchester instrument – was poor → servicing PIK&MIX (Jan-Feb 2012) – loan lidar from Leosphere (weak) MEVALI (March 2012) – lidar back from Leosphere – weaker signal April 2012 – tested in the lab for T dependence – no result Water spill preventers + lidar breather installed FENNEC (June 2012) – quantitative data analysis planned July 2012 – laser broken – “self fix” (new laser) – good and strong signal SAMBBA (Sept-Oct 2012) - quantitative data analysis planned ALS 450 out of production © Crown copyright Met Office

Temperature effect Ground-based In flight © Crown copyright Met Office

i. Buttons: temperature effect proven RED – ground based GREEN – COALESC BLUE - FENNEC Rayleigh scattering constant ( m=0. 00415) © Crown copyright Met Office

i. Buttons for housekeeping To what temperature cycle are we exposing the lidar? Something happened on Thursday, 29 September 2011 at 15: 45! © Crown copyright Met Office

Lidar upgrade • In collaboration with Patrick Chazette (LSCE) • New “better” polarising beam splitters Paris, January 2013 ? © Crown copyright Met Office

Finding molecular layers: is the contour plot adequate? Fennec Is this blue (low signal) due to aerosols or Rayleigh scattering? © Crown copyright Met Office

Finding molecular layers: is the contour plot adequate? aerosols or alignment problem? molecular this slope is very different from Rayleigh scattering: must be aerosols!! © Crown copyright Met Office

Inversion of lidar signals Range corrected signal Aerosol extinction coefficient Reference Height 2 1 2 3 4 5 Reference Height 1 extinction backscatter © Crown copyright Met Office LIDAR RATIO

Setting layers manually for analysis accept/reject aerosol and depol calibration ranges ch 0: yellow surface spike ch 1: brown cloud tops © Crown copyright Met Office

Volcanic ash: extinction coefficient retrievals spatially resolved detection signal inversion 17 May lidar ratio 60 sr ~ 30% uncertainty quantitative ~1800 lidar profiles inspected + analysed (6 flights) © Crown copyright Met Office

Ash concentration estimates courtesy of B. Johnson, J. Dorsey and M. Gallagher Date fc 4 May 5 May 14 May 16 May 17 May 18 May 0. 52 0. 72 0. 97 0. 78 0. 82 0. 75 © Crown copyright Met Office Kext (m 2/g) 0. 92 0. 65 0. 62 0. 82 0. 74 Uncertainty: ~ factor of 2

Volcanic ash Lidar vs. NAME • reasonable overall magnitude • positional errors sometimes • model uncertainties: source term, meteorology, sub-scale processes courtesy of H. Webster (Atmospheric Dispersion Group) © Crown copyright Met Office

Volcanic ash - Lidar vs. SEVIRI courtesy of P. Francis and M. Cooke (Satellite Applications) 17 May © Crown copyright Met Office

ACEMED: validation of CALIPSO In collaboration with V. Amiridis, A. Tsekeri and E. Marinou (National Observatory of Athens) © Crown copyright Met Office

COSIC: contrails In collaboration with H. Jones (U. Manchester) © Crown copyright Met Office

Verification of cirrus model Courtesy of A. Baran © Crown copyright Met Office

SAMBBA © Crown copyright Met Office

SAMBBA © Crown copyright Met Office

FENNEC © Crown copyright Met Office

Questions and answers © Crown copyright Met Office