| 725 | | ||[=#PA0503 PA0503] || z0* exceeds 0.5 * surface-layer height at ... surface grid point (i,j) = (...,...) || Monin-Obukhov similarity is assumed between the surface and the first computational grid point normal to the surface. Because of the staggered grid, the distance between these two points is half of the grid spacing in the respective direction, i.e. {{{dz/2}}} in vertical direction. The height {{{z = dz/2}}} defines the top of the (analytical) logarithmic layer {{{z_mo}}} (the surface layer height). Functions like {{{ln(z_mo/z0)}}}, where {{{z0}}} is the roughness length, are used to calculate characteristic surface layer variables like u* or theta*. This mathematically requires that {{{z_mo > z0}}}, or in other words, that {{{z0 < dz/2}}}. In case you have run into this error, you either need to reduce the roughness length {{{z0}}} (via namelist parameter roughness_length or in the static driver) or enlarge the grid spacing {{{dz}}}. Same holds for roughness length {{{z0h}}} for temperature and {{{z0q}}} for moisture. \\ \\ '''Attention:''' This message is given only once (for the first grid point where the exceedance has been detected). Be aware that there might be more grid points where {{{z0}}} exceeds the surface-layer height. \\ \\ In case of water surfaces {{{z0}}} is automatically calculated each time step via the Charnock relation and respectively checked. No information about grid point location(s) is given for that case. More than one location may have been detected. \\ \\ |
| 726 | | Set initialization parameter {{{allow_roughness_limitation}}} = ''.TRUE.'' in order to allow for an automatical limitation of {{{z0}}} to a maximum value of {{{0.5 * z_mo}}}, which is equivalent to {{{0.25 * dz}}}. || |
| | 725 | ||[=#PA0503 PA0503] || z0* exceeds 0.5 * surface-layer height at ... surface grid point (i,j) = (...,...) || Monin-Obukhov similarity is assumed between the surface and the first computational grid point normal to the surface. Because of the staggered grid, the distance between these two points is half of the grid spacing in the respective direction, i.e. {{{dz/2}}} in vertical direction. The height {{{z = dz/2}}} defines the top of the (analytical) logarithmic layer {{{z_mo}}} (the surface layer height). Functions like {{{ln(z_mo/z0)}}}, where {{{z0}}} is the roughness length, are used to calculate characteristic surface layer variables like u* or theta*. This mathematically requires that {{{z_mo > z0}}}, or in other words, that {{{z0 < dz/2}}}. In case you have run into this error, you either need to reduce the roughness length {{{z0}}} (via namelist parameter roughness_length or in the static driver) or enlarge the grid spacing {{{dz}}}. Same holds for roughness length {{{z0h}}} for temperature and {{{z0q}}} for moisture. \\ \\ '''Attention:''' This message is given only once (for the first grid point where the exceedance has been detected). Be aware that there might be more grid points where {{{z0}}} exceeds the surface-layer height. \\ \\ In case of water surfaces {{{z0}}} is automatically calculated each time step via the Charnock relation and respectively checked. No information about grid point location(s) is given for that case. More than one location may have been detected. \\ \\ Set initialization parameter {{{allow_roughness_limitation}}} = ''.TRUE.'' in order to allow for an automatical limitation of {{{z0}}} to a maximum value of {{{0.5 * z_mo}}}, which is equivalent to {{{0.25 * dz}}}. || |
