Add specificHumidity to ADPUPA BUFR DUMP Python API (NOAA-EMC#1246)

This PR adds specificHumidity to the ADPUPA BUFR DUMP Python API. The
following file has been changed:
~/ush/ioda/bufr2ioda/bufr2ioda_adpupa.py

The specificHumidity is calculated using the dewPoint and pressure. The
information is extracted from the prepBUFR codes and also documented.

The validation of the output obs is performed using the specificHumidity
from the prepBUFR data. For more details, please check: NOAA-EMC#1193

Co-authored-by: Praveen Singh <[email protected]>

ush/ioda/bufr2ioda/bufr2ioda_adpupa.py

@@ -37,6 +37,21 @@ def Compute_WindComponents_from_WindDirection_and_WindSpeed(wdir, wspd):
     return uob, vob
 
 
+def Compute_SpecificHumidity_from_dewPoint_and_Pressure(tmdp, prlc):
+
+    # est is saturated vapor pressure in Mb
+    est = 6.1078 * np.exp((17.269 * (tmdp - 273.16))/((tmdp - 273.16)+237.3))
+    # Change est from Mb to Pa
+    est = est*100.
+
+    # specificHumidity (qob) is in kg/kg
+    qob = (0.622 * est)/(prlc - (0.378 * est))
+    qob = ma.array(qob)
+    qob = ma.masked_values(qob, qob.fill_value)
+
+    return qob
+
+
 def bufr_to_ioda(config, logger):
 
     subsets = config["subsets"]
@@ -191,6 +206,7 @@ def bufr_to_ioda(config, logger):
     dewpointTemperatureOE = np.float32(np.ma.masked_array(np.full((len(tmdp)), 0.0)))
     windEastwardOE = np.float32(np.ma.masked_array(np.full((len(wspd)), 0.0)))
     windNorthwardOE = np.float32(np.ma.masked_array(np.full((len(wspd)), 0.0)))
+    specificHumidityOE = np.float32(np.ma.masked_array(np.full((len(qob)), 0.0)))
 
     end_time = time.time()
     running_time = end_time - start_time
@@ -208,6 +224,9 @@ def bufr_to_ioda(config, logger):
     logger.debug(f'   uob min/max = {uob.min()} {uob.max()}')
     logger.debug(f'   vob min/max = {vob.min()} {vob.max()}')
 
+    qob = Compute_SpecificHumidity_from_dewPoint_and_Pressure(tmdp, prlc)
+    logger.debug(f'   qob min/max = {qob.min()} {qob.max()}')
+
     end_time = time.time()
     running_time = end_time - start_time
     logger.info(f'Processing time for creating derived variables : {running_time} seconds')
@@ -236,6 +255,7 @@ def bufr_to_ioda(config, logger):
     logger.debug(f'     wspd      shape = {wspd.shape}')
     logger.debug(f'     uob       shape = {uob.shape}')
     logger.debug(f'     vob       shape = {vob.shape}')
+    logger.debug(f'     qob       shape = {qob.shape}')
 
     logger.debug(f'     qmpr      shape = {qmpr.shape}')
     logger.debug(f'     qmat      shape = {qmat.shape}')
@@ -264,6 +284,7 @@ def bufr_to_ioda(config, logger):
     logger.debug(f'     wspd      type  = {wspd.dtype}')
     logger.debug(f'     uob       type  = {uob.dtype}')
     logger.debug(f'     vob       type  = {vob.dtype}')
+    logger.debug(f'     qob       type  = {qob.dtype}')
 
     logger.debug(f'     qmpr      type  = {qmpr.dtype}')
     logger.debug(f'     qmat      type  = {qmat.dtype}')
@@ -365,6 +386,12 @@ def bufr_to_ioda(config, logger):
         .write_attr('long_name', 'Northward Wind') \
         .write_data(vob)
 
+    # Specific Humidity
+    obsspace.create_var('ObsValue/specificHumidity', dtype=qob.dtype, fillval=qob.fill_value) \
+        .write_attr('units', 'kg kg-1') \
+        .write_attr('long_name', 'Specific Humidity') \
+        .write_data(qob)
+
     # Pressure Quality Marker
     obsspace.create_var('QualityMarker/pressure', dtype=qmpr.dtype, fillval=qmpr.fill_value) \
         .write_attr('long_name', 'Pressure Quality Marker') \
@@ -420,6 +447,12 @@ def bufr_to_ioda(config, logger):
         .write_attr('long_name', 'Northward Wind Observation Error') \
         .write_data(windNorthwardOE)
 
+    # Specific Humidity Observation Error
+    obsspace.create_var('ObsError/specificHumidity', dtype=qob.dtype, fillval=qob.fill_value) \
+        .write_attr('units', 'kg kg-1') \
+        .write_attr('long_name', 'Specific Humidity Observation Error') \
+        .write_data(specificHumidityOE)
+
     end_time = time.time()
     running_time = end_time - start_time
     logger.info(f"Running time for splitting and output IODA: {running_time} seconds")