PIMS/CSC Weekly Seminar: Chiara Piccolo and Mike Cullen

  • Date: 05/11/2012
  • Time: 14:30
Chiara Piccolo (Met Office, UK) and Mike Cullen (Met Office, UK)

Simon Fraser University


Adaptive mesh method in the Met Office variational data assimilation system




A frequent problem in forecasting fog or icy roads in a numerical
weather prediction system is attributed to the misinterpretation of the
boundary layer structure in the assimilation procedure. Case studies
showed that much of the misinterpretation of temperature inversions and
stratocumulus layers in the assimilation is due to inappropriate
background error covariances. This paper looks at the application of
adaptive mesh methods in the Met Office variational assimilation system
to modify the background error correlations in the boundary layer when
temperature inversions or stratocumulus layers are present in the
background state. Results show improvements in the analysis root mean
square errors with respect to radiosonde observations and surface
observations and improvements in forecast errors in two metre
temperature in the presence of low clouds. This enhancement in two metre
temperature forecast is attributed to reduced background vertical
correlations and increased temperature background error variances in the
assimilation due to the movement of the grid near the surface. Impacts
above surface will be also discussed.

Other Information: 

Location: TASC-2, Rm 8500