#include <Main/fg_props.hxx>
#include <Main/util.hxx>
+#include "atmosphere.hxx"
#include "fgmetar.hxx"
#include "environment_ctrl.hxx"
metar_valid(false),
setup_winds_aloft(true),
wind_interpolation_required(true),
- station_elevation_ft(0.0),
// Interpolation constant definitions.
EnvironmentUpdatePeriodSec( 0.2 ),
MaxWindChangeKtsSec( 0.2 ),
return d > 180.0 ? d - 360.0 : d;
}
+// Return the sea level pressure for a metar observation, in inHg.
+// This is different from QNH because it accounts for the current
+// temperature at the observation point.
+// metarPressure in inHg
+// fieldHt in ft
+// fieldTemp in C
+
+static double reducePressureSl(double metarPressure, double fieldHt,
+ double fieldTemp)
+{
+ double elev = fieldHt * SG_FEET_TO_METER;
+ double fieldPressure
+ = FGAtmo::fieldPressure(elev, metarPressure * atmodel::inHg);
+ double slPressure = P_layer(0, elev, fieldPressure,
+ fieldTemp + atmodel::freezing,
+ atmodel::ISA::lam0);
+ return slPressure / atmodel::inHg;
+}
+
void
FGMetarCtrl::update(double dt)
{
bool reinit_required = false;
bool layer_rebuild_required = false;
+ double station_elevation_ft = station_elevation_n->getDoubleValue();
if (first_update) {
double dir = base_wind_dir_n->getDoubleValue()+magnetic_variation_n->getDoubleValue();
fgDefaultWeatherValue("visibility-m", metarvis);
double metarpressure = pressure_n->getDoubleValue();
- fgDefaultWeatherValue("pressure-sea-level-inhg", metarpressure);
+ fgDefaultWeatherValue("pressure-sea-level-inhg",
+ reducePressureSl(metarpressure,
+ station_elevation_ft,
+ temperature_n->getDoubleValue()));
// We haven't already loaded a METAR, so apply it immediately.
vector<SGPropertyNode_ptr> layers = clouds_n->getChildren("layer");
double pressure = boundary_sea_level_pressure_n->getDoubleValue();
double metarpressure = pressure_n->getDoubleValue();
- if( pressure != metarpressure ) {
- pressure = interpolate_val( pressure, metarpressure, MaxPressureChangeInHgSec );
+ double newpressure = reducePressureSl(metarpressure,
+ station_elevation_ft,
+ temperature_n->getDoubleValue());
+ if( pressure != newpressure ) {
+ pressure = interpolate_val( pressure, newpressure, MaxPressureChangeInHgSec );
fgDefaultWeatherValue("pressure-sea-level-inhg", pressure);
reinit_required = true;
}
}
}
}
-
- set_temp_at_altitude(temperature_n->getDoubleValue(), station_elevation_ft);
- set_dewpoint_at_altitude(dewpoint_n->getDoubleValue(), station_elevation_ft);
+ set_temp_at_altitude(temperature_n->getDoubleValue(), station_elevation_ft);
+ set_dewpoint_at_altitude(dewpoint_n->getDoubleValue(), station_elevation_ft);
//TODO: check if temperature/dewpoint have changed. This requires reinit.
// Force an update of the 3D clouds