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[GFS] Calculate cloud levels from pressure and temperature

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This commit is contained in:
Roland Rossgotterer
2019-02-18 17:27:20 +01:00
committed by Mat Sutcliffe
parent 5ea8b7376e
commit 5b10abd63d
2 changed files with 51 additions and 24 deletions
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69
src/plugins/weatherdata/gfs/weatherdatagfs.cpp
View File

@@ -44,12 +44,11 @@ namespace BlackWxPlugin
{ { {6, 1} }, { TCDC, "Total Cloud Cover", "%" } },
};
double millibarToLevel(double millibar)
// https://physics.stackexchange.com/questions/333475/how-to-calculate-altitude-from-current-temperature-and-pressure
double calculateAltitudeFt(double seaLevelPressurePa, double atmosphericPressurePa, double temperatureK)
{
static const double hPaStandardPressure = CPhysicalQuantitiesConstants::ICAOFlightLevelPressure().value(CPressureUnit::mbar());
millibar /= 100;
double level = (1 - std::pow(millibar / hPaStandardPressure, 0.190284)) * 145366.45;
return level;
double altitude = (std::pow(seaLevelPressurePa / atmosphericPressurePa, 0.19022) - 1) * temperatureK * 3.28084 / 0.0065;
return altitude;
}
CWeatherDataGfs::CWeatherDataGfs(QObject *parent) :
@@ -287,17 +286,19 @@ namespace BlackWxPlugin
if (QThread::currentThread()->isInterruptionRequested()) { return; }
CTemperatureLayerList temperatureLayers;
CWindLayerList windLayers;
for (auto isobaricLayerIt = gfsGridPoint.isobaricLayers.begin(); isobaricLayerIt != gfsGridPoint.isobaricLayers.end(); ++isobaricLayerIt)
for (const GfsIsobaricLayer &isobaricLayer : gfsGridPoint.isobaricLayers)
{
GfsIsobaricLayer isobaricLayer = isobaricLayerIt.value();
CAltitude level(isobaricLayerIt.key(), CAltitude::MeanSeaLevel, CLengthUnit::ft());
double level = gfsGridPoint.isobaricLayers.key(isobaricLayer);
double altitudeFt = calculateAltitudeFt(gfsGridPoint.pressureAtMsl, level, isobaricLayer.temperature);
CAltitude altitude(altitudeFt, CAltitude::MeanSeaLevel, CLengthUnit::ft());
auto temperature = CTemperature { isobaricLayer.temperature, CTemperatureUnit::K() };
auto dewPoint = calculateDewPoint(temperature, isobaricLayer.relativeHumidity);
CTemperatureLayer temperatureLayer(level, temperature, dewPoint, isobaricLayer.relativeHumidity);
CTemperatureLayer temperatureLayer(altitude, temperature, dewPoint, isobaricLayer.relativeHumidity);
temperatureLayers.push_back(temperatureLayer);
double windDirection = -1 * CMathUtils::rad2deg(std::atan2(-isobaricLayer.windU, isobaricLayer.windV));
@@ -305,19 +306,21 @@ namespace BlackWxPlugin
if (windDirection < 0.0) { windDirection += 360.0; }
if (windDirection >= 360.0) { windDirection -= 360.0; }
double windSpeed = std::hypot(isobaricLayer.windU, isobaricLayer.windV);
CWindLayer windLayer(level, CAngle(windDirection, CAngleUnit::deg()), CSpeed(windSpeed, CSpeedUnit::m_s()), {});
CWindLayer windLayer(altitude, CAngle(windDirection, CAngleUnit::deg()), CSpeed(windSpeed, CSpeedUnit::m_s()), {});
windLayers.push_back(windLayer);
}
CCloudLayerList cloudLayers;
for (auto cloudLayerIt = gfsGridPoint.cloudLayers.begin(); cloudLayerIt != gfsGridPoint.cloudLayers.end(); ++cloudLayerIt)
for (const GfsCloudLayer &gfsCloudLayer : gfsGridPoint.cloudLayers)
{
if (std::isnan(cloudLayerIt.value().bottomLevel) || std::isnan(cloudLayerIt.value().topLevel)) { continue; }
if (std::isnan(gfsCloudLayer.bottomLevelPressure) || std::isnan(gfsCloudLayer.topLevelPressure) || std::isnan(gfsCloudLayer.topLevelTemperature)) { continue; }
CCloudLayer cloudLayer;
cloudLayer.setBase(CAltitude(cloudLayerIt.value().bottomLevel, CAltitude::MeanSeaLevel, CLengthUnit::ft()));
cloudLayer.setTop(CAltitude(cloudLayerIt.value().topLevel, CAltitude::MeanSeaLevel, CLengthUnit::ft()));
cloudLayer.setCoveragePercent(cloudLayerIt.value().totalCoverage);
double bottomLevelFt = calculateAltitudeFt(gfsGridPoint.pressureAtMsl, gfsCloudLayer.bottomLevelPressure, gfsCloudLayer.topLevelTemperature);
double topLevelFt = calculateAltitudeFt(gfsGridPoint.pressureAtMsl, gfsCloudLayer.topLevelPressure, gfsCloudLayer.topLevelTemperature);
cloudLayer.setBase(CAltitude(bottomLevelFt, CAltitude::MeanSeaLevel, CLengthUnit::ft()));
cloudLayer.setTop(CAltitude(topLevelFt, CAltitude::MeanSeaLevel, CLengthUnit::ft()));
cloudLayer.setCoveragePercent(gfsCloudLayer.totalCoverage);
if (gfsGridPoint.surfaceSnow > 0.0) { cloudLayer.setPrecipitation(CCloudLayer::Snow); }
if (gfsGridPoint.surfaceRain > 0.0) { cloudLayer.setPrecipitation(CCloudLayer::Rain); }
@@ -533,7 +536,7 @@ namespace BlackWxPlugin
switch(typeFirstFixedSurface)
{
case GroundOrWaterSurface: level = 0.0; break;
case IsobaricSurface: level = std::round(millibarToLevel(valueFirstFixedSurface)); break;
case IsobaricSurface: level = valueFirstFixedSurface; break;
case MeanSeaLevel: level = 0.0; break;
default: CLogMessage(this).warning(u"Unexpected first fixed surface type: %1") << typeFirstFixedSurface; return;
}
@@ -592,7 +595,8 @@ namespace BlackWxPlugin
case PRATE: setPrecipitationRate(gfld->fld); break;
case CRAIN: setSurfaceRain(gfld->fld); break;
case CSNOW: setSurfaceSnow(gfld->fld); break;
default: CLogMessage(this).error(u"Unexpected parameterValue in Template 4.8: %1 (%2)") << parameterValue.code << parameterValue.name; return;
case TMP: setCloudTemperature(gfld->fld, typeFirstFixedSurface, grib2CloudLevelHash.value(typeFirstFixedSurface)); break;
default: CLogMessage(this).warning(u"Unexpected parameterValue in Template 4.8: %1 (%2)") << parameterValue.code << parameterValue.name; return;
}
}
@@ -641,21 +645,42 @@ namespace BlackWxPlugin
for (auto &gridPoint : m_gfsWeatherGrid)
{
static const g2float minimumLayer = 0.0;
double levelFt = std::numeric_limits<double>::quiet_NaN();
double levelPressure = std::numeric_limits<double>::quiet_NaN();
g2float fieldValue = fld[gridPoint.fieldPosition];
// A value of 9.999e20 is undefined. Check that the pressure value is below
if (fieldValue < 9.998e20f) { levelFt = millibarToLevel(fld[gridPoint.fieldPosition]); }
if (fieldValue < 9.998e20f) { levelPressure = fld[gridPoint.fieldPosition]; }
switch (surfaceType)
{
case LowCloudBottomLevel:
case MiddleCloudBottomLevel:
case HighCloudBottomLevel:
if (fieldValue > minimumLayer) { gridPoint.cloudLayers[level].bottomLevel = levelFt; }
if (fieldValue > minimumLayer) { gridPoint.cloudLayers[level].bottomLevelPressure = levelPressure; }
break;
case LowCloudTopLevel:
case MiddleCloudTopLevel:
case HighCloudTopLevel:
if (fieldValue > minimumLayer) { gridPoint.cloudLayers[level].topLevel = levelFt; }
if (fieldValue > minimumLayer) { gridPoint.cloudLayers[level].topLevelPressure = levelPressure; }
break;
default:
Q_ASSERT(false);
break;
}
}
}
void CWeatherDataGfs::setCloudTemperature(const g2float *fld, int surfaceType, int level)
{
for (auto &gridPoint : m_gfsWeatherGrid)
{
double temperature = std::numeric_limits<double>::quiet_NaN();
g2float fieldValue = fld[gridPoint.fieldPosition];
if (fieldValue < 9.998e20f) { temperature = fld[gridPoint.fieldPosition]; }
switch (surfaceType)
{
case LowCloudTopLevel:
case MiddleCloudTopLevel:
case HighCloudTopLevel:
gridPoint.cloudLayers[level].topLevelTemperature = temperature;
break;
default:
Q_ASSERT(false);

6
src/plugins/weatherdata/gfs/weatherdatagfs.h
View File

@@ -116,9 +116,10 @@ namespace BlackWxPlugin
struct GfsCloudLayer
{
double bottomLevel = 0.0;
double topLevel = 0.0;
double bottomLevelPressure = 0.0;
double topLevelPressure = 0.0;
double totalCoverage = 0.0;
double topLevelTemperature = 0.0;
};
struct GfsGridPoint
@@ -151,6 +152,7 @@ namespace BlackWxPlugin
void setWindU(const g2float *fld, double level);
void setCloudCoverage(const g2float *fld, int level);
void setCloudLevel(const g2float *fld, int surfaceType, int level);
void setCloudTemperature(const g2float *fld, int surfaceType, int level);
void setPressureAtMsl(const g2float *fld);
void setSurfaceRain(const g2float *fld);
void setSurfaceSnow(const g2float *fld);