Engineering topics

Wobus, R. L.

Publications and source records attributed to Wobus, R. L..

3 records

NASA NTRS1984

Long-term dynamical stability and transition in a spectral model

The relationship between blocking and multiple equilibria was investigated in a two layer model of the Northern Hemisphere January heating and boundary conditions are imposed. The truncation varies over global wavenumbers 4-8 and the coefficients of horizontal diffusion of heat and potential vorticity are varied about realistic values. It is shown that while severely truncated models can exhibit multiple quasi equilibria under realistic domain, forcing, and boundary conditions, higher resolution is required to allow realistic transitions to be mediated by strong baroclinic wave activity. It is indicated that for extended range forecasting blocking transitions are not likely to be forecast well unless the associated synoptic events can be forecasted statistically.

Wobus, R. L.↗

NASA NTRS1984

A new parameterization of 15 micron radiative transfer for a GCM

In order to make the Wu-Kaplan longwave radiative transfer parameterization (Krishnamurthy, 1982) presently used in the 9 layer GLAS GCM more suitable for use at higher horizontal and vertical resolutions, the fixed CO2 transmittance tables and climatological O3 transmittances are replaced with appropriate models. Results of off line tests of simple models of CO2 transmittance as a function of atmospheric temperature profile and surface pressure, based on the technique used by Susskind et al. (1983) in the GLAS physical retrieval scheme are given. The models are evaluated in terms of tansmittance error, flux divergence error, and equilibrium temperature error. The transmittances of CO2 averaged over each of the spectral bands 500-660 cm-1 and 660-800 cm-1 are modeled, following Susskind et al., 1983, as products of effective layer transmittances.

Wobus, R. L.↗

NASA NTRS1981

A numerical model study of long-term planetary wave predictability

A numerical model was developed to study planetary wave behavior over periods up to 4 months under the influences of stochastic and diffusive forcing by synoptic scale motions and of sea surface temperature anomalies. The model is suitable for Monte Carlo experiments which provide ensemble mean and variance predictions and permit the response to heating anomalies to be partly separated from random variability. The model incorporates the linear-balanced dynamical equations for wind at two tropospheric levels and temperature at one level. The model atmosphere is forced by semiempirical January heating linearly dependent on local air temperature. Topography and the lower boundary layer are represented by vertical motion and drag functions, respectively, of the lower level wind. The linear phase speeds of Rossby waves are modified to reflect the effect of the stratosphere.

Wobus, R. L.↗