TY - GEN
AU - J. Barkmeijer
AU - Roberto Buizza
AU - T.N. Palmer
AU - K. Puri
AU - J.-F. Mahfouf
AB - With the introduction of diabatic processes in the forward and adjoint tangent models of the European Centre for Medium-Range Weather Forecasts' model, it is possible to determine singular vectors (SVs) for situations where diabatic physics may be important in producing perturbation growth. In this paper, the linear physical parametrizations are used to compute SVs for the tropical region, or subsets thereof, with an optimization time of 48 h. Perturbation growth is measured in terms of the so-called total energy norm, augmented with a term for specific humidity. Difficulties that may arise in computing tropical SVs such as associated with spurious upper-tropospheric perturbation growth is descrived. Also the impact on the SV structure by including a specific humidity term in the defining norm is discussed. Using a term for specific humidity based on background error statistics in the norm at initial time yields SVs with a more realistic specific humidity vertical profile. SVs are determined in various configurations for two tropical cyclones. Results show that targeting in the vicinity of the cyclone is required to obtain SVs associated with the cyclone dynamics. The dominant targeted SVs for tropical cyclones show resemblance to fast-growing structures found for idealized vortices.
BT - ECMWF Technical Memoranda
CY - Shinfield Park, Reading
DA - 2000
DO - 10.21957/w2wl93l
LA - eng
M1 - 297
N2 - With the introduction of diabatic processes in the forward and adjoint tangent models of the European Centre for Medium-Range Weather Forecasts' model, it is possible to determine singular vectors (SVs) for situations where diabatic physics may be important in producing perturbation growth. In this paper, the linear physical parametrizations are used to compute SVs for the tropical region, or subsets thereof, with an optimization time of 48 h. Perturbation growth is measured in terms of the so-called total energy norm, augmented with a term for specific humidity. Difficulties that may arise in computing tropical SVs such as associated with spurious upper-tropospheric perturbation growth is descrived. Also the impact on the SV structure by including a specific humidity term in the defining norm is discussed. Using a term for specific humidity based on background error statistics in the norm at initial time yields SVs with a more realistic specific humidity vertical profile. SVs are determined in various configurations for two tropical cyclones. Results show that targeting in the vicinity of the cyclone is required to obtain SVs associated with the cyclone dynamics. The dominant targeted SVs for tropical cyclones show resemblance to fast-growing structures found for idealized vortices.
PB - ECMWF
PP - Shinfield Park, Reading
PY - 2000
T2 - ECMWF Technical Memoranda
TI - Tropical singular vectors computed with linearized diabatic physics
UR - https://www.ecmwf.int/node/7946
ER -