Add Grib 41

Author: SebastianThomas

grib/src/main/java/ucar/nc2/grib/grib2/Grib2Pds.java

@@ -68,6 +68,8 @@ public static Grib2Pds factory(int template, byte[] input) {
         return new Grib2Pds32(input);
       case 40:
         return new Grib2Pds40(input);
+      case 41:
+        return new Grib2Pds41(input);
       case 48:
         return new Grib2Pds48(input);
       case 60:
@@ -1698,6 +1700,65 @@ public int templateLength() {
 
   ///////////////////////////////////////////////////////////////////////////////
 
+  /*
+   * Product definition template 4.41 – individual ensemble forecast, control and perturbed, for atmospheric
+   * constituents
+   * Octet No. Contents
+   * 10 Parameter category (see Code table 4.1)
+   * 11 Parameter number (see Code table 4.2)
+   * 12–13 Constituent Type (see Code Table 4.230)
+   * 14 Type of Generating Process (see Code table 4.3)
+   * 15 Background Process
+   * 16 Generating Process Identifier
+   * 17–18 Hours of observational data cut-off after reference time (see Note)
+   * 19 Minutes of observational data cut-off after reference time
+   * 20 Indicator of unit of time range (see Code table 4.4)
+   * 21-24 Forecast time in units defined by octet 18
+   * 25 Type of first fixed surface (see Code table 4.5)
+   * 26 Scale factor of first fixed surface
+   * 27–30 Scaled value of first fixed surface
+   * 31 Type of second fixed surface (see Code table 4.5)
+   * 32 Scale factor of second fixed surface
+   * 33-36 Scaled value of second fixed surface
+   * 37 Type of ensemble forecast (see Code table 4.6)
+   * 38 Perturbation number
+   * 39 Number of forecasts in ensemble
+   * Note: Hours greater than 65534 will be coded as 65534.
+   */
+
+  private static class Grib2Pds41 extends Grib2Pds40 implements PdsEnsemble {
+
+    Grib2Pds41(byte[] input) {
+      super(input);
+    }
+
+    public boolean isEnsemble() {
+      return true;
+    }
+
+    /* Type of ensemble forecast (see Code table 4.6) */
+    public int getPerturbationType() {
+      return getOctet(37);
+    }
+
+    /* Perturbation Ensemble Member Number */
+    public int getPerturbationNumber() {
+      return getOctet(38);
+    }
+
+    /* Number of forecasts in ensemble */
+    public int getNumberEnsembleForecasts() {
+      return getOctet(39);
+    }
+
+    @Override
+    public int templateLength() {
+      return 39;
+    }
+  }
+
+  ///////////////////////////////////////////////////////////////////////////////
+
   /*
    * Product definition template 4.48 – analysis or forecast at a horizontal level or in a horizontal layer at a point
    * in time for optical properties of aerosol

grib/src/test/data/index/icon-ch2-eps-202606230000-0-poacsnc-ctrl.grib2

@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2026 University Corporation for Atmospheric Research/Unidata
+ * See LICENSE for license information.
+ */
+
+package ucar.nc2.grib.grib2;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.io.IOException;
+import java.util.List;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Test data from github issue https://github.com/Unidata/netcdf-java/issues/41
+ * Data was used to create a .gbx9 file for testing.
+ * <p>
+ * PDS (Secton 4) output from ecCodes grib_dump at the end of the file, uses as a basis for
+ * testing PDS (Secton 4) parsing
+ */
+@RunWith(JUnit4.class)
+public class TestPds41 {
+
+  private Grib2Pds pds;
+
+  @Before
+  public void openTestFile() throws IOException {
+    String testfile = "../grib/src/test/data/index/icon-ch2-eps-202606230000-0-poacsnc-ctrl.grib2.gbx9";
+
+    Grib2Index gi = new Grib2Index();
+    boolean success = gi.readIndex(testfile, -1);
+    assertThat(success).isTrue();
+    List<Grib2Record> records = gi.getRecords();
+    Grib2Record record = records.get(0);
+    pds = record.getPDS();
+  }
+
+  @Test
+  public void testPdsBasic() {
+    assertThat(pds.getRawLength()).isEqualTo(63);
+    assertThat(pds.getTemplateNumber()).isEqualTo(41);
+  }
+
+  // check overrides
+  @Test
+  public void testGenProcessType() {
+    assertThat(pds.getGenProcessType()).isEqualTo(4);;
+  }
+
+  @Test
+  public void testBackProcessId() {
+    assertThat(pds.getBackProcessId()).isEqualTo(0);;
+  }
+
+  @Test
+  public void testGenProcessId() {
+    assertThat(pds.getGenProcessId()).isEqualTo(142);;
+  }
+
+  @Test
+  public void testTimeUnit() {
+    assertThat(pds.getTimeUnit()).isEqualTo(0);
+  }
+
+  @Test
+  public void testLevelType1() {
+    assertThat(pds.getLevelType1()).isEqualTo(150);
+  }
+
+  @Test
+  public void testLevelScale1() {
+    assertThat(pds.getLevelScale1()).isEqualTo(0);
+  }
+
+  @Test
+  public void testLevelValue1() {
+    assertThat(pds.getLevelValue1()).isEqualTo(80);
+  }
+
+  @Test
+  public void testLevelType2() {
+    assertThat(pds.getLevelType2()).isEqualTo(150);
+  }
+
+  @Test
+  public void testLevelScale2() {
+    assertThat(pds.getLevelScale2()).isEqualTo(0);
+  }
+
+  @Test
+  public void testLevelValue2() {
+    assertThat(pds.getLevelValue2()).isEqualTo(81);
+  }
+
+  @Test
+  public void testTemplateLength() {
+    assertThat(pds.templateLength()).isEqualTo(39);
+  }
+
+  @Test
+  public void testIsEnsemble() {
+    assertThat(pds.isEnsemble()).isTrue();
+  }
+
+  @Test
+  public void testPerturbationType() {
+    assertThat(((Grib2Pds.PdsEnsemble) pds).getPerturbationType()).isEqualTo(192);
+  }
+
+  @Test
+  public void testPerturbationNumber() {
+    assertThat(((Grib2Pds.PdsEnsemble) pds).getPerturbationNumber()).isEqualTo(0);
+  }
+
+  @Test
+  public void testNumberEnsembleForecasts() {
+    assertThat(((Grib2Pds.PdsEnsemble) pds).getNumberEnsembleForecasts()).isEqualTo(21);
+  }
+}
+
+// grib_dump -O icon-ch2-eps-202606230000-0-poacsnc-ctrl.grib2
+// ***** FILE: icon-ch2-eps-202606230000-0-poacsnc-ctrl.grib2
+// ...
+// ====================== SECTION_4 ( length=63, padding=0 ) ======================
+// 1-4 section4Length = 63
+// 5 numberOfSection = 4
+// 6-7 NV = 6
+// 8-9 productDefinitionTemplateNumber = 41 [Individual ensemble forecast, control and perturbed, at a horizontal level
+// or in a horizontal layer at a point in time for atmospheric chemical constituents (grib2/tables/15/4.0.table) ]
+// 10 parameterCategory = 20 [Atmospheric chemical constituents (grib2/tables/15/4.1.0.table) ]
+// 11 parameterNumber = 60 [Unknown code table entry (grib2/tables/15/4.2.0.20.table) ]
+// 12-13 constituentType = 62300 [Unknown code table entry (grib2/tables/15/4.230.table) ]
+// 14 typeOfGeneratingProcess = 4 [Ensemble forecast (grib2/tables/15/4.3.table) ]
+// 15 backgroundProcess = 0
+// 16 generatingProcessIdentifier = 142
+// 17-18 hoursAfterDataCutoff = 0
+// 19 minutesAfterDataCutoff = 0
+// 20 indicatorOfUnitForForecastTime = 0 [Minute (grib2/tables/15/4.4.table) ]
+// 21-24 forecastTime = 0
+// 25 typeOfFirstFixedSurface = 150 [Generalized vertical height coordinate (grib2/tables/15/4.5.table) ]
+// 26 scaleFactorOfFirstFixedSurface = 0
+// 27-30 scaledValueOfFirstFixedSurface = 80
+// 31 typeOfSecondFixedSurface = 150 [Generalized vertical height coordinate (grib2/tables/15/4.5.table) ]
+// 32 scaleFactorOfSecondFixedSurface = 0
+// 33-36 scaledValueOfSecondFixedSurface = 81
+// 37 typeOfEnsembleForecast = 192 [Unknown code table entry (grib2/tables/15/4.6.table) ]
+// 38 perturbationNumber = 0
+// 39 numberOfForecastsInEnsemble = 21
+// 40-43 nlev = 81
+// 44-47 numberOfVGridUsed = 4
+// 48-63 uuidOfVGrid = 16 {
+// 4d, 01, b8, 87, 1a, 1c, 80, 1c, 03, 16, f2, 80, f2, e6, 2c, c0
+// } # bytes uuidOfVGrid