Improvements in Forecasting Intense Rainfall: Results from the FRANC (Forecasting Rainfall Exploiting New Data Assimilation Techniques and Novel Observations of Convection) Project
Sarah L. Dance,
Susan P. Ballard,
Ross N. Bannister,
Peter Clark,
Hannah L. Cloke,
Timothy Darlington,
David L. A. Flack,
Suzanne L. Gray,
Lee Hawkness-Smith,
Nawal Husnoo,
Anthony J. Illingworth,
Graeme A. Kelly,
Humphrey W. Lean,
Dingmin Li,
Nancy K. Nichols,
John C. Nicol,
Andrew Oxley,
Robert S. Plant,
Nigel M. Roberts,
Ian Roulstone,
David Simonin,
Robert J. Thompson,
Joanne A. Waller
Affiliations
Sarah L. Dance
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Susan P. Ballard
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Ross N. Bannister
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Peter Clark
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Hannah L. Cloke
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Timothy Darlington
Met Office, Fitzroy Rd, Exeter EX1 3PB, UK
David L. A. Flack
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Suzanne L. Gray
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Lee Hawkness-Smith
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Nawal Husnoo
Met Office, Fitzroy Rd, Exeter EX1 3PB, UK
Anthony J. Illingworth
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Graeme A. Kelly
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Humphrey W. Lean
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Dingmin Li
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Nancy K. Nichols
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
John C. Nicol
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Andrew Oxley
Department of Mathematics, University of Surrey, Guildford GU2 7XH, UK
Robert S. Plant
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Nigel M. Roberts
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Ian Roulstone
Department of Mathematics, University of Surrey, Guildford GU2 7XH, UK
David Simonin
MetOffice@Reading, Meteorology Building, University of Reading, Reading RG6 6BB, UK
Robert J. Thompson
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Joanne A. Waller
Department of Meteorology, University of Reading, Reading RG6 6BB, UK
The FRANC project (Forecasting Rainfall exploiting new data Assimilation techniques and Novel observations of Convection) has researched improvements in numerical weather prediction of convective rainfall via the reduction of initial condition uncertainty. This article provides an overview of the project’s achievements. We highlight new radar techniques: correcting for attenuation of the radar return; correction for beams that are over 90% blocked by trees or towers close to the radar; and direct assimilation of radar reflectivity and refractivity. We discuss the treatment of uncertainty in data assimilation: new methods for estimation of observation uncertainties with novel applications to Doppler radar winds, Atmospheric Motion Vectors, and satellite radiances; a new algorithm for implementation of spatially-correlated observation error statistics in operational data assimilation; and innovative treatment of moist processes in the background error covariance model. We present results indicating a link between the spatial predictability of convection and convective regimes, with potential to allow improved forecast interpretation. The research was carried out as a partnership between University researchers and the Met Office (UK). We discuss the benefits of this approach and the impact of our research, which has helped to improve operational forecasts for convective rainfall events.
