Reading an Argo cycle

Reading an Argo cycle#

The descending profile#

As mentioned before, some floats also make measurements in the first descending phase of the first cycle. The data is in the <R/D>_001D.nc file

cy1D = xr.open_dataset('../../Data/202107-ArgoData/dac/coriolis/6901254/profiles/R6901254_001D.nc')

print(f"The dimesions of TEMP are:\n {cy1D.TEMP.dims[0]}:{cy1D.TEMP.shape[0]} \n {cy1D.TEMP.dims[1]}:{cy1D.TEMP.shape[1]}")

The dimesions of TEMP are:
 N_PROF:1 
 N_LEVELS:51

in this case there is only one profile, let’s plot it together with the ascending data (cy1):

fig, ax = plt.subplots(1,2,figsize=(8,10))

#Temperature
ax[0].plot(cy1D.TEMP[0],-cy1D.PRES[0],'k-',label='N_PROF=0 Descending',linewidth=3.0)
ax[0].plot(cy1.TEMP[0],-cy1.PRES[0],'b-',label='N_PROF=0 Ascending')
ax[0].plot(cy1.TEMP[1],-cy1.PRES[1],'ro',label='N_PROF=1 Ascending')
ax[0].set_title(cy1.TEMP.long_name)
ax[0].set_ylabel(cy1.PRES.long_name)
ax[0].grid()
ax[0].legend()

#Salinity
ax[1].plot(cy1D.PSAL[0],-cy1D.PRES[0],'k-',label='N_PROF=0 Descending',linewidth=3.0)
ax[1].plot(cy1.PSAL[0],-cy1.PRES[0],'b-',label='N_PROF=0 Ascending')
ax[1].plot(cy1.PSAL[1],-cy1.PRES[1],'ro',label='N_PROF=1 Ascending')
ax[1].set_title(cy1.PSAL.long_name)
ax[1].grid()

As indicated in the figure, the first descending is only until the parking depth.

Geographical information#

The NetCDF file includes information about the geographical position of the observations (LONGITUDE and LATITUDE) and the date of the observation (JULD).

for variable in ['LONGITUDE', 'LATITUDE' , 'JULD']:
   print(f"The {cy1.data_vars[variable].long_name} is in the variable {variable}")

The Longitude of the station, best estimate is in the variable LONGITUDE
The Latitude of the station, best estimate is in the variable LATITUDE
The Julian day (UTC) of the station relative to REFERENCE_DATE_TIME is in the variable JULD

Let’s plot it

fig, ax = plt.subplots(figsize=(8,8))

ax.plot(cy1D.LONGITUDE[0],cy1D.LATITUDE[0],'ko',label='001D N_PROF=0 Descending')
ax.plot(cy1.LONGITUDE[0],cy1.LATITUDE[0],'bo',label='001 N_PROF=0 Ascending')
#ax.set_title(cy1..long_name)
ax.set_xlabel(cy1.LONGITUDE.long_name)
ax.set_ylabel(cy1.LATITUDE.long_name)
ax.text(cy1D.LONGITUDE[0],cy1D.LATITUDE[0],'Date of observation for 001D:'+cy1D.JULD[0].values.astype(str), fontsize=14)
ax.text(cy1.LONGITUDE[0],cy1.LATITUDE[0],'Date of observation for 001:'+cy1.JULD[0].values.astype(str), fontsize=14)
ax.grid()
ax.legend();

../../_images/f29fa87d160e737a54032e8a3b90c30eed05e7c8106cedb21eeccf23e04750f0.png

The 2 ascending profiles in 001 have, obviously, the same time stamp:

print(cy1.JULD[0].values.astype(str))
print(cy1.JULD[1].values.astype(str))

2018-10-25T05:30:00.000000000
2018-10-25T05:30:00.000000000

Note that for some floats there is a <R/D>_000.n or even a <R/D>_000D.n file.

Meta information in the cycle file#

The NetCDF file for each cycle includes a lot of additional information about each one of the profiles in it. Let’s take a look at the basic information.

print(f"For cycle {cy1D.CYCLE_NUMBER.astype(int).values} The {cy1D.DIRECTION.long_name} (DIRECTION) is {cy1D.DIRECTION.values.astype(str)}")
print(f"For cycle  {cy1.CYCLE_NUMBER.astype(int).values} the {cy1.DIRECTION.long_name}  (DIRECTION) is {cy1.DIRECTION.values.astype(str)}")

For cycle [1] The Direction of the station profiles (DIRECTION) is ['D']
For cycle  [1 1] the Direction of the station profiles  (DIRECTION) is ['A' 'A']

A is for ascending and D for descending.

And all the meta information of the float, and for each profile within each cycle, among others:

for variable in ['PLATFORM_NUMBER','DATA_CENTRE','PROJECT_NAME','PI_NAME']:
   print(f"The {cy1.data_vars[variable].long_name} ({variable}) is {cy1.data_vars[variable].values.astype(str)}")

The Float unique identifier (PLATFORM_NUMBER) is ['6901254 ' '6901254 ']
The Data centre in charge of float data processing (DATA_CENTRE) is ['IF' 'IF']
The Name of the project (PROJECT_NAME) is ['ARGO SPAIN                                                      '
 'ARGO SPAIN                                                      ']
The Name of the principal investigator (PI_NAME) is ['Pedro Velez                                                     '
 'Pedro Velez                                                     ']

We can also access the dimession that define the profile

for key in cy1.sizes.keys():
    print(key,cy1.sizes[key])

N_PROF 2
N_PARAM 3
N_LEVELS 97
N_HISTORY 3
N_CALIB 1

N_LEVELS is the number of vertical levels, i.e. in pressure. N_PROF is the number of profiles within the cycle, as we saw previously. N_PARAM is the number of parameters, 3 for this float: TEMP, PSAL and PRES

Later we will explain N_CALIB and N_HISTORY

Meta data#

There is a lot of additional meta information in the <FloatWmoID>_meta.nc file

Mdata = xr.open_dataset('../../Data/202107-ArgoData/dac/coriolis/6901254/6901254_meta.nc')

Always, the basic information appears in all the netcdf files of an Argo float:

for variable in ['PLATFORM_NUMBER','DATA_CENTRE','PROJECT_NAME','PI_NAME']:
   print(f"The {Mdata.data_vars[variable].long_name} ({variable}) is {Mdata.data_vars[variable].values.astype(str)}")

The Float unique identifier (PLATFORM_NUMBER) is 6901254 
The Data centre in charge of float real-time processing (DATA_CENTRE) is IF
The Program under which the float was deployed (PROJECT_NAME) is ARGO SPAIN                                                      
The Name of the principal investigator (PI_NAME) is Pedro Velez                                                     

and some examples of additional information in the <FloatWmoID>_meta.nc file

for variable in ['FIRMWARE_VERSION','BATTERY_TYPE','DEPLOYMENT_PLATFORM','CONFIG_PARAMETER_NAME','SENSOR_SERIAL_NO']:
   print(f"The {Mdata.data_vars[variable].long_name} ({variable}) is {Mdata.data_vars[variable].values.astype(str)}")

The Firmware version for the float (FIRMWARE_VERSION) is n/a                             
The Type of battery packs in the float (BATTERY_TYPE) is LITHIUM                                                         
The Identifier of the deployment platform (DEPLOYMENT_PLATFORM) is ANGELES ALVARI?O                
The Name of configuration parameter (CONFIG_PARAMETER_NAME) is ['CONFIG_CycleTime_hours                                                                                                          '
 'CONFIG_ParkPressure_dbar                                                                                                        '
 'CONFIG_ProfilePressure_dbar                                                                                                     '
 'CONFIG_DescentToParkPresSamplingTime_seconds                                                                                    '
 'CONFIG_Direction_NUMBER                                                                                                         ']
The Serial number of the sensor (SENSOR_SERIAL_NO) is ['n/a             ' 'n/a             ' 'n/a             ']

The full descritpion of all the variables is in the Argo user’s Manual