Background Error Statistics-
It is used in most atmospheric analysis methods, including optimal interpolation, 3DVAR and 4DVAR and Kalman Filter-based methods. Usually the Background Error covariance matrix of the control variables was assumed to be isotropic and homogeneous, but a flow-dependent covariance matrix could be derived with certain techniques. The simplest way to derive an isotropic and homogeneous error covariance matrix is to use NMC-method based on a historical dataset of the model forecasts.
Boundary Condition-
In numerical weather prediction the boundary conditions for a regional model can be specified as a function of the solution of a larger scale model at, and just within, the boundary of the regional model.
Blocking-
Obstructing, on a large scale, of the normal west-to-east progress of migratory cyclones and anticyclones. A common form of blocking is an Omega Ridge or Omega Block.
Box Models-
Mathematical models that simulate the chemistry at a given point in space as a function of time. Advection of chemical species in and out of the box is not considered. These models are used particularly to study the evolution of homogeneous air masses and for Lagrangian
air-shed studies.
Broadband Emissivity-
The ratio of the power emitted by a body at a temperature T to the power emitted if the body obeyed Plank's radiation law. Strictly,
emissivity should be qualified by the frequency, direction, and even polarization state of the emitted radiation.
