|
|
|
|
|
| Elfouhaily, T; Thompson, Dr; Chapron, Bertrand; Vandemark, D. |
| In this paper we describe modifications to a previous theory for the altimeter electromagnetic bias (EM bias) of Srokosz [1986]. A major correction introduces a scaling of Srokosz's model by nonnegligible dimensionless ratios that depend on the slope variance of both long and short waves. With these modifications the EM bias is no longer simply a function of the cross skewness between surface elevation and slope but now depends on the variance ratios that represent the modulation between short and long waves, Inclusion of these ratios can reduce previous EM bias estimates by as much as 50%. Different directions for the longwave and shortwave field are also accounted for in the two-dimensional development of our approach. A radar frequency dependence... |
| Tipo: Text |
|
| Ano: 2000 |
URL: http://archimer.ifremer.fr/doc/00000/10585/9395.pdf |
| |
|
|
| Chapron, Bertrand; Vandemark, D; Elfouhaily, T; Thompson, Dr; Gaspar, P; Labroue, S. |
| A nonparametric SSB model, derived using the TOPEX altimeter, is analyzed to show a new decomposition of the form SSB = bH(s) + f(sigma (o)), where b is 0.03 and the function of radar cross section (sigma (o)) is an absolute second-order range correction residing outside the conventional nondimensional SSB model. Expected variability in the dominant bH(s) term and its ties to the long wave orbital velocity and shorter-scale slope variances are discussed using a physic ally-motivated restatement of recent EM bias theory. The geometry of steep near-breaking waves, neglected within current theory, is invoked as one plausible explanation for the observed H-s-independent SSB component. |
| Tipo: Text |
|
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00000/10275/10691.pdf |
| |
|
|
| Elfouhaily, T; Thompson, Dr; Chapron, Bertrand; Vandemark, D. |
| The modulation of short ocean waves by longer ones is a likely contributor to the radar altimeter's electromagnetic ranging bias (EM bias). An analytic model to account for this component of the EM bias is developed here under a two-scale two-dimensional hydrodynamic assumption. Following the principle of wave action balance, a standard hydrodynamic modulation transfer function is used to establish that the longer modulating waves enter the EM bias formulation not only through their elevation and slope variables but also through their quadratures. These latter contributions help to explain the role of long-wave slope and orbital velocity fields within the EM bias problem. Simplified analytical expressions are derived using linear Gaussian statistics for... |
| Tipo: Text |
|
| Ano: 2001 |
URL: https://archimer.ifremer.fr/doc/00000/10365/9499.pdf |
| |
|
|
|
