Dsg subset writers (#1361)

* fixups

* minor fixes for dsgsubsetWriter

* fix station altitudes

Author: haileyajohnson

cdm/core/src/main/java/ucar/nc2/ft/point/writer/CFPointWriter.java

@@ -515,16 +515,16 @@ record = (Structure) writer.addVariable(null, recordName, DataType.STRUCTURE, re
 
         Formatter coordNames = new Formatter().format("%s %s %s", stnFeature.getTimeName(), latName, lonName);
         if (!Double.isNaN(pointFeat.getLocation().getAltitude())) {
-          altitudeCoordinateName = stnFeature.getAltName();
           coordNames.format(" %s", altitudeCoordinateName);
         }
 
         if (writer.getVersion().isExtendedModel()) {
           addDataVariablesExtended(pointFeat.getFeatureData(), coordNames.toString());
         }
         addDataVariablesClassic(recordDim, pointFeat.getFeatureData(), dataMap, coordNames.toString());
-
       }
+      // TODO: note if we iterate all stations, the data at the first station is changed to the data at the last station
+      break;
     }
 
     addCoordinatesClassic(recordDim, obsCoords, dataMap);

cdm/core/src/main/java/ucar/nc2/ft/point/writer/WriterCFStationCollection.java

@@ -109,6 +109,7 @@ public void writeHeader(List<StationFeature> stns, @Nullable StationPointFeature
 
     llbb = CFPointWriterUtils.getBoundingBox(stnList); // gets written in super.finish();
 
+    altitudeCoordinateName = altName;
     coords.add(VariableSimpleBuilder
         .makeScalar(stationIndexName, "station index for this observation record", null, DataType.INT)
         .addAttribute(CF.INSTANCE_DIMENSION, stationDimName).build());

cdm/core/src/main/java/ucar/nc2/ft/point/writer/WriterCFStationProfileCollection.java

@@ -114,13 +114,13 @@ public void writeHeader(List<StationFeature> stations) throws IOException {
 
 
       obsCoords.add(VariableSimpleBuilder
-          .makeScalar(stationProfile.getTimeName(), "time of measurement", timeUnit.toString(), DataType.DOUBLE)
+          .makeScalar(stationProfile.getTimeName(), "nominal time of profile", timeUnit.toString(), DataType.DOUBLE)
           .build());
       if (altUnits != null) {
-        altitudeCoordinateName = stationProfile.getAltName();
+        altitudeCoordinateName = altName;
         obsCoords
             .add(VariableSimpleBuilder.makeScalar(altitudeCoordinateName, "obs altitude", altUnits, DataType.DOUBLE)
-                .addAttribute(CF.STANDARD_NAME, "altitude")
+                .addAttribute(CF.STANDARD_NAME, altitudeCoordinateName)
                 .addAttribute(CF.POSITIVE, CF1Convention.getZisPositive(altitudeCoordinateName, altUnits)).build());
       }
     }

cdm/core/src/main/java/ucar/nc2/ft/point/writer2/WriterCFStationCollection.java

@@ -112,6 +112,7 @@ protected void writeHeader(List<StationFeature> stations) throws IOException {
       }
     }
 
+    altitudeCoordinateName = stationAltName;
     llbb = ucar.nc2.ft.point.writer.CFPointWriterUtils.getBoundingBox(stnList); // gets written in super.finish();
     coords.add(VariableSimpleBuilder
         .makeScalar(stationIndexName, "station index for this observation record", null, DataType.INT)

cdm/core/src/main/java/ucar/nc2/ft/point/writer2/WriterCFStationProfileCollection.java

@@ -118,7 +118,8 @@ protected void writeHeader(List<StationFeature> stations) throws IOException {
         coverageCollections.add(profile);
 
         obsCoords.add(VariableSimpleBuilder
-            .makeScalar(profile.getTimeName(), "time of measurement", timeUnit.toString(), DataType.DOUBLE).build());
+            .makeScalar(profile.getTimeName(), "nominal time of profile", timeUnit.toString(), DataType.DOUBLE)
+            .build());
 
         altitudeCoordinateName = profile.getAltName();
         obsCoords