ucar.unidata.geoloc.vertical.HybridSigmaPressure Maven / Gradle / Ivy
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/*
* Copyright 1998-2009 University Corporation for Atmospheric Research/Unidata
*
* Portions of this software were developed by the Unidata Program at the
* University Corporation for Atmospheric Research.
*
* Access and use of this software shall impose the following obligations
* and understandings on the user. The user is granted the right, without
* any fee or cost, to use, copy, modify, alter, enhance and distribute
* this software, and any derivative works thereof, and its supporting
* documentation for any purpose whatsoever, provided that this entire
* notice appears in all copies of the software, derivative works and
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* software or in any product that includes this software. The names UCAR
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*
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*/
package ucar.unidata.geoloc.vertical;
import ucar.ma2.*;
import ucar.nc2.*;
import ucar.unidata.util.Parameter;
import java.io.IOException;
import java.util.List;
/**
* Create a 3D height(z,y,x) array using the netCDF CF convention formula for
* "Hybrid Sigma Pressure".
* pressure(x,y,z) = a(z)*p0 + b(z)*surfacePressure(x,y)
* or
*
pressure(x,y,z) = ap(z) + b(z)*surfacePressure(x,y)
*
* @author caron
* @see http://cf-pcmdi.llnl.gov/
*/
public class HybridSigmaPressure extends VerticalTransformImpl {
/**
* P-naught identifier
*/
public static final String P0 = "P0_variableName";
/**
* Surface pressure name identifier
*/
public static final String PS = "SurfacePressure_variableName";
/**
* The "a" variable name identifier
*/
public static final String A = "A_variableName";
/**
* The "a" variable name identifier
*/
public static final String AP = "AP_variableName";
/**
* The "b" variable name identifier
*/
public static final String B = "B_variableName";
/**
* value of p-naught
*/
private double p0;
/**
* ps, a, and b variables
*/
private Variable psVar, aVar, bVar, p0Var;
/**
* a and b Arrays
*/
private Array aArray = null,
bArray = null;
/**
* Construct a coordinate transform for sigma pressure
*
* @param ds netCDF dataset
* @param timeDim time dimension
* @param params list of transformation Parameters
*/
public HybridSigmaPressure(NetcdfFile ds, Dimension timeDim, List params) {
super(timeDim);
String psName = getParameterStringValue(params, PS);
String aName = getParameterStringValue(params, A);
String bName = getParameterStringValue(params, B);
String p0Name = getParameterStringValue(params, P0);
String apName = getParameterStringValue(params, AP);
if (apName != null)
aVar = ds.findVariable(apName);
else
aVar = ds.findVariable(aName);
psVar = ds.findVariable(psName);
bVar = ds.findVariable(bName);
if (p0Name != null)
p0Var = ds.findVariable(p0Name);
units = ds.findAttValueIgnoreCase(psVar, "units", "none");
}
/**
* Get the 3D vertical coordinate array for this time step.
*
* @param timeIndex the time index. Ignored if !isTimeDependent().
* @return vertical coordinate array
* @throws IOException problem reading data
* @throws InvalidRangeException _more_
*/
public ArrayDouble.D3 getCoordinateArray(int timeIndex)
throws IOException, InvalidRangeException {
Array psArray = readArray(psVar, timeIndex);
if (null == aArray) {
aArray = aVar.read();
bArray = bVar.read();
p0 = (p0Var == null) ? 1.0 : p0Var.readScalarDouble();
}
int nz = (int) aArray.getSize();
Index aIndex = aArray.getIndex();
Index bIndex = bArray.getIndex();
// it's possible to have rank 3 because pressure can have a level, usually 1
// Check if rank 3 and try to reduce
if( psArray.getRank() == 3)
psArray = psArray.reduce(0);
int[] shape2D = psArray.getShape();
int ny = shape2D[0];
int nx = shape2D[1];
Index psIndex = psArray.getIndex();
ArrayDouble.D3 press = new ArrayDouble.D3(nz, ny, nx);
double ps;
for (int z = 0; z < nz; z++) {
double term1 = aArray.getDouble(aIndex.set(z)) * p0;
double bz = bArray.getDouble(bIndex.set(z));
for (int y = 0; y < ny; y++) {
for (int x = 0; x < nx; x++) {
ps = psArray.getDouble(psIndex.set( y, x));
press.set(z, y, x, term1 + bz * ps);
}
}
}
return press;
}
}