Accessing Argo data by float using Argopy

Although the goal of the Argo Online school is to teach the basics of the Argo data, and therefore, we explain the data using the primary source, it is worth mentioning argopy:

is a python library dedicated to Argo data access, manipulation and visualisation for standard users as well as Argo experts. the Argo dataset is very complex: with thousands of different variables, tens of reference tables and a user manual more than 100 pages long: argopy aims to help you navigate this complex realm.

In this notebook we show a few examples, but we refer to the argopy Gallery for a more detailled explanation:

Fist, as usual, import the libraries:

import numpy as np
import matplotlib as mpl
from matplotlib import pyplot as plt

import xarray as xr
xr.set_options(display_expand_attrs = False)

<xarray.core.options.set_options at 0x164405400>

Import argopy and set-up a data fetcher:

import argopy
argopy.reset_options()
argopy.clear_cache()

from argopy import ArgoFloat
from argopy import ArgoIndex
from argopy.stores import gdacfs

You can load all profiles from a float:

apDS = ArgoFloat(6901254).open_dataset('prof')

apDS 

<xarray.Dataset> Size: 3MB
Dimensions:                       (N_PROF: 166, N_PARAM: 3, N_LEVELS: 98,
                                   N_CALIB: 1, N_HISTORY: 0)
Dimensions without coordinates: N_PROF, N_PARAM, N_LEVELS, N_CALIB, N_HISTORY
Data variables: (12/64)
    DATA_TYPE                     <U16 64B ...
    FORMAT_VERSION                <U4 16B ...
    HANDBOOK_VERSION              <U4 16B ...
    REFERENCE_DATE_TIME           datetime64[ns] 8B ...
    DATE_CREATION                 datetime64[ns] 8B ...
    DATE_UPDATE                   datetime64[ns] 8B ...
    ...                            ...
    HISTORY_ACTION                (N_HISTORY, N_PROF) <U1 0B ...
    HISTORY_PARAMETER             (N_HISTORY, N_PROF) <U1 0B ...
    HISTORY_START_PRES            (N_HISTORY, N_PROF) float32 0B ...
    HISTORY_STOP_PRES             (N_HISTORY, N_PROF) float32 0B ...
    HISTORY_PREVIOUS_VALUE        (N_HISTORY, N_PROF) float32 0B ...
    HISTORY_QCTEST                (N_HISTORY, N_PROF) <U1 0B ...
Attributes: (8)

xarray.Dataset

• Dimensions:
  • N_PROF: 166
  • N_PARAM: 3
  • N_LEVELS: 98
  • N_CALIB: 1
  • N_HISTORY: 0
• Coordinates: (0)
• Data variables: (64)
  • DATA_TYPE
    ()
    <U16
    ...

    long_name :

    Data type

    conventions :

    Argo reference table 1

    casted :

    1

    [1 values with dtype=<U16]

  • FORMAT_VERSION
    ()
    <U4
    ...

    long_name :

    File format version

    casted :

    1

    [1 values with dtype=<U4]

  • HANDBOOK_VERSION
    ()
    <U4
    ...

    long_name :

    Data handbook version

    casted :

    1

    [1 values with dtype=<U4]

  • REFERENCE_DATE_TIME
    ()
    datetime64[ns]
    ...

    long_name :

    Date of reference for Julian days

    conventions :

    YYYYMMDDHHMISS

    casted :

    1

    [1 values with dtype=datetime64[ns]]

  • DATE_CREATION
    ()
    datetime64[ns]
    ...

    long_name :

    Date of file creation

    conventions :

    YYYYMMDDHHMISS

    casted :

    1

    [1 values with dtype=datetime64[ns]]

  • DATE_UPDATE
    ()
    datetime64[ns]
    ...

    long_name :

    Date of update of this file

    conventions :

    YYYYMMDDHHMISS

    casted :

    1

    [1 values with dtype=datetime64[ns]]

  • PLATFORM_NUMBER
    (N_PROF)
    int64
    ...

    long_name :

    Float unique identifier

    conventions :

    WMO float identifier : A9IIIII

    casted :

    1

    [166 values with dtype=int64]

  • PROJECT_NAME
    (N_PROF)
    <U64
    ...

    long_name :

    Name of the project

    casted :

    1

    [166 values with dtype=<U64]

  • PI_NAME
    (N_PROF)
    <U64
    ...

    long_name :

    Name of the principal investigator

    casted :

    1

    [166 values with dtype=<U64]

  • STATION_PARAMETERS
    (N_PROF, N_PARAM)
    <U16
    ...

    long_name :

    List of available parameters for the station

    conventions :

    Argo reference table 3

    casted :

    1

    [498 values with dtype=<U16]

  • CYCLE_NUMBER
    (N_PROF)
    int64
    ...

    long_name :

    Float cycle number

    conventions :

    0...N, 0 : launch cycle (if exists), 1 : first complete cycle

    casted :

    1

    [166 values with dtype=int64]

  • DIRECTION
    (N_PROF)
    <U1
    ...

    long_name :

    Direction of the station profiles

    conventions :

    A: ascending profiles, D: descending profiles

    casted :

    1

    [166 values with dtype=<U1]

  • DATA_CENTRE
    (N_PROF)
    <U2
    ...

    long_name :

    Data centre in charge of float data processing

    conventions :

    Argo reference table 4

    casted :

    1

    [166 values with dtype=<U2]

  • DC_REFERENCE
    (N_PROF)
    <U32
    ...

    long_name :

    Station unique identifier in data centre

    conventions :

    Data centre convention

    casted :

    1

    [166 values with dtype=<U32]

  • DATA_STATE_INDICATOR
    (N_PROF)
    <U4
    ...

    long_name :

    Degree of processing the data have passed through

    conventions :

    Argo reference table 6

    casted :

    1

    [166 values with dtype=<U4]

  • DATA_MODE
    (N_PROF)
    <U1
    ...

    long_name :

    Delayed mode or real time data

    conventions :

    R : real time; D : delayed mode; A : real time with adjustment

    casted :

    1

    [166 values with dtype=<U1]

  • PLATFORM_TYPE
    (N_PROF)
    <U32
    ...

    long_name :

    Type of float

    conventions :

    Argo reference table 23

    casted :

    1

    [166 values with dtype=<U32]

  • FLOAT_SERIAL_NO
    (N_PROF)
    <U32
    ...

    long_name :

    Serial number of the float

    casted :

    1

    [166 values with dtype=<U32]

  • FIRMWARE_VERSION
    (N_PROF)
    <U32
    ...

    long_name :

    Instrument firmware version

    casted :

    1

    [166 values with dtype=<U32]

  • WMO_INST_TYPE
    (N_PROF)
    int64
    ...

    long_name :

    Coded instrument type

    conventions :

    Argo reference table 8

    casted :

    1

    [166 values with dtype=int64]

  • JULD
    (N_PROF)
    datetime64[ns]
    ...

    long_name :

    Julian day (UTC) of the station relative to REFERENCE_DATE_TIME

    standard_name :

    time

    conventions :

    Relative julian days with decimal part (as parts of day)

    resolution :

    0.0

    axis :

    T

    casted :

    1

    [166 values with dtype=datetime64[ns]]

  • JULD_QC
    (N_PROF)
    int64
    ...

    long_name :

    Quality on date and time

    conventions :

    Argo reference table 2

    casted :

    1

    [166 values with dtype=int64]

  • JULD_LOCATION
    (N_PROF)
    datetime64[ns]
    ...

    long_name :

    Julian day (UTC) of the location relative to REFERENCE_DATE_TIME

    conventions :

    Relative julian days with decimal part (as parts of day)

    resolution :

    0.0

    casted :

    1

    [166 values with dtype=datetime64[ns]]

  • LATITUDE
    (N_PROF)
    float64
    ...

    long_name :

    Latitude of the station, best estimate

    standard_name :

    latitude

    units :

    degree_north

    valid_min :

    -90.0

    valid_max :

    90.0

    axis :

    Y

    casted :

    1

    [166 values with dtype=float64]

  • LONGITUDE
    (N_PROF)
    float64
    ...

    long_name :

    Longitude of the station, best estimate

    standard_name :

    longitude

    units :

    degree_east

    valid_min :

    -180.0

    valid_max :

    180.0

    axis :

    X

    casted :

    1

    [166 values with dtype=float64]

  • POSITION_QC
    (N_PROF)
    int64
    ...

    long_name :

    Quality on position (latitude and longitude)

    conventions :

    Argo reference table 2

    casted :

    1

    [166 values with dtype=int64]

  • POSITIONING_SYSTEM
    (N_PROF)
    <U8
    ...

    long_name :

    Positioning system

    casted :

    1

    [166 values with dtype=<U8]

  • PROFILE_PRES_QC
    (N_PROF)
    <U3
    ...

    long_name :

    Global quality flag of PRES profile

    conventions :

    Argo reference table 2a

    casted :

    1

    [166 values with dtype=<U3]

  • PROFILE_TEMP_QC
    (N_PROF)
    <U3
    ...

    long_name :

    Global quality flag of TEMP profile

    conventions :

    Argo reference table 2a

    casted :

    1

    [166 values with dtype=<U3]

  • PROFILE_PSAL_QC
    (N_PROF)
    <U3
    ...

    long_name :

    Global quality flag of PSAL profile

    conventions :

    Argo reference table 2a

    casted :

    1

    [166 values with dtype=<U3]

  • VERTICAL_SAMPLING_SCHEME
    (N_PROF)
    <U256
    ...

    long_name :

    Vertical sampling scheme

    conventions :

    Argo reference table 16

    casted :

    1

    [166 values with dtype=<U256]

  • CONFIG_MISSION_NUMBER
    (N_PROF)
    int64
    ...

    long_name :

    Unique number denoting the missions performed by the float

    conventions :

    1...N, 1 : first complete mission

    casted :

    1

    [166 values with dtype=int64]

  • PRES
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Sea water pressure, equals 0 at sea-level

    standard_name :

    sea_water_pressure

    units :

    decibar

    valid_min :

    0.0

    valid_max :

    12000.0

    C_format :

    %7.1f

    FORTRAN_format :

    F7.1

    resolution :

    1.0

    axis :

    Z

    casted :

    1

    [16268 values with dtype=float32]

  • PRES_QC
    (N_PROF, N_LEVELS)
    int64
    ...

    long_name :

    quality flag

    conventions :

    Argo reference table 2

    casted :

    1

    [16268 values with dtype=int64]

  • PRES_ADJUSTED
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Sea water pressure, equals 0 at sea-level

    standard_name :

    sea_water_pressure

    units :

    decibar

    valid_min :

    0.0

    valid_max :

    12000.0

    C_format :

    %7.1f

    FORTRAN_format :

    F7.1

    resolution :

    1.0

    axis :

    Z

    casted :

    1

    [16268 values with dtype=float32]

  • PRES_ADJUSTED_QC
    (N_PROF, N_LEVELS)
    int64
    ...

    long_name :

    quality flag

    conventions :

    Argo reference table 2

    casted :

    1

    [16268 values with dtype=int64]

  • PRES_ADJUSTED_ERROR
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Contains the error on the adjusted values as determined by the delayed mode QC process

    units :

    decibar

    C_format :

    %7.1f

    FORTRAN_format :

    F7.1

    resolution :

    1.0

    casted :

    1

    [16268 values with dtype=float32]

  • TEMP
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Sea temperature in-situ ITS-90 scale

    standard_name :

    sea_water_temperature

    units :

    degree_Celsius

    valid_min :

    -2.5

    valid_max :

    40.0

    C_format :

    %9.3f

    FORTRAN_format :

    F9.3

    resolution :

    0.001

    casted :

    1

    [16268 values with dtype=float32]

  • TEMP_QC
    (N_PROF, N_LEVELS)
    int64
    ...

    long_name :

    quality flag

    conventions :

    Argo reference table 2

    casted :

    1

    [16268 values with dtype=int64]

  • TEMP_ADJUSTED
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Sea temperature in-situ ITS-90 scale

    standard_name :

    sea_water_temperature

    units :

    degree_Celsius

    valid_min :

    -2.5

    valid_max :

    40.0

    C_format :

    %9.3f

    FORTRAN_format :

    F9.3

    resolution :

    0.001

    casted :

    1

    [16268 values with dtype=float32]

  • TEMP_ADJUSTED_QC
    (N_PROF, N_LEVELS)
    int64
    ...

    long_name :

    quality flag

    conventions :

    Argo reference table 2

    casted :

    1

    [16268 values with dtype=int64]

  • TEMP_ADJUSTED_ERROR
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Contains the error on the adjusted values as determined by the delayed mode QC process

    units :

    degree_Celsius

    C_format :

    %9.3f

    FORTRAN_format :

    F9.3

    resolution :

    0.001

    casted :

    1

    [16268 values with dtype=float32]

  • PSAL
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Practical salinity

    standard_name :

    sea_water_salinity

    units :

    psu

    valid_min :

    2.0

    valid_max :

    41.0

    C_format :

    %9.3f

    FORTRAN_format :

    F9.3

    resolution :

    0.001

    casted :

    1

    [16268 values with dtype=float32]

  • PSAL_QC
    (N_PROF, N_LEVELS)
    int64
    ...

    long_name :

    quality flag

    conventions :

    Argo reference table 2

    casted :

    1

    [16268 values with dtype=int64]

  • PSAL_ADJUSTED
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Practical salinity

    standard_name :

    sea_water_salinity

    units :

    psu

    valid_min :

    2.0

    valid_max :

    41.0

    C_format :

    %9.3f

    FORTRAN_format :

    F9.3

    resolution :

    0.001

    casted :

    1

    [16268 values with dtype=float32]

  • PSAL_ADJUSTED_QC
    (N_PROF, N_LEVELS)
    int64
    ...

    long_name :

    quality flag

    conventions :

    Argo reference table 2

    casted :

    1

    [16268 values with dtype=int64]

  • PSAL_ADJUSTED_ERROR
    (N_PROF, N_LEVELS)
    float32
    ...

    long_name :

    Contains the error on the adjusted values as determined by the delayed mode QC process

    units :

    psu

    C_format :

    %9.3f

    FORTRAN_format :

    F9.3

    resolution :

    0.001

    casted :

    1

    [16268 values with dtype=float32]

  • PARAMETER
    (N_PROF, N_CALIB, N_PARAM)
    <U16
    ...

    long_name :

    List of parameters with calibration information

    conventions :

    Argo reference table 3

    casted :

    1

    [498 values with dtype=<U16]

  • SCIENTIFIC_CALIB_EQUATION
    (N_PROF, N_CALIB, N_PARAM)
    <U256
    ...

    long_name :

    Calibration equation for this parameter

    casted :

    1

    [498 values with dtype=<U256]

  • SCIENTIFIC_CALIB_COEFFICIENT
    (N_PROF, N_CALIB, N_PARAM)
    <U256
    ...

    long_name :

    Calibration coefficients for this equation

    casted :

    1

    [498 values with dtype=<U256]

  • SCIENTIFIC_CALIB_COMMENT
    (N_PROF, N_CALIB, N_PARAM)
    <U256
    ...

    long_name :

    Comment applying to this parameter calibration

    casted :

    1

    [498 values with dtype=<U256]

  • SCIENTIFIC_CALIB_DATE
    (N_PROF, N_CALIB, N_PARAM)
    datetime64[ns]
    ...

    long_name :

    Date of calibration

    conventions :

    YYYYMMDDHHMISS

    casted :

    1

    [498 values with dtype=datetime64[ns]]

  • HISTORY_INSTITUTION
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Institution which performed action

    conventions :

    Argo reference table 4

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_STEP
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Step in data processing

    conventions :

    Argo reference table 12

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_SOFTWARE
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Name of software which performed action

    conventions :

    Institution dependent

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_SOFTWARE_RELEASE
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Version/release of software which performed action

    conventions :

    Institution dependent

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_REFERENCE
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Reference of database

    conventions :

    Institution dependent

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_DATE
    (N_HISTORY, N_PROF)
    datetime64[ns]
    ...

    long_name :

    Date the history record was created

    conventions :

    YYYYMMDDHHMISS

    casted :

    1

    [0 values with dtype=datetime64[ns]]

  • HISTORY_ACTION
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Action performed on data

    conventions :

    Argo reference table 7

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_PARAMETER
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Station parameter action is performed on

    conventions :

    Argo reference table 3

    casted :

    1

    [0 values with dtype=<U1]

  • HISTORY_START_PRES
    (N_HISTORY, N_PROF)
    float32
    ...

    long_name :

    Start pressure action applied on

    units :

    decibar

    casted :

    1

    [0 values with dtype=float32]

  • HISTORY_STOP_PRES
    (N_HISTORY, N_PROF)
    float32
    ...

    long_name :

    Stop pressure action applied on

    units :

    decibar

    casted :

    1

    [0 values with dtype=float32]

  • HISTORY_PREVIOUS_VALUE
    (N_HISTORY, N_PROF)
    float32
    ...

    long_name :

    Parameter/Flag previous value before action

    casted :

    1

    [0 values with dtype=float32]

  • HISTORY_QCTEST
    (N_HISTORY, N_PROF)
    <U1
    ...

    long_name :

    Documentation of tests performed, tests failed (in hex form)

    conventions :

    Write tests performed when ACTION=QCP$; tests failed when ACTION=QCF$

    casted :

    1

    [0 values with dtype=<U1]

• Indexes: (0)
• Attributes: (8)

  title :

  Argo float vertical profile

  institution :

  FR GDAC

  source :

  Argo float

  history :

  2023-04-24T09:47:18Z creation

  references :

  http://www.argodatamgt.org/Documentation

  user_manual_version :

  3.1

  Conventions :

  Argo-3.1 CF-1.6

  featureType :

  trajectoryProfile

apDS.TEMP

<xarray.DataArray 'TEMP' (N_PROF: 166, N_LEVELS: 98)> Size: 65kB
[16268 values with dtype=float32]
Dimensions without coordinates: N_PROF, N_LEVELS
Attributes: (9)

xarray.DataArray

'TEMP'

• N_PROF: 166
• N_LEVELS: 98

• ...

  [16268 values with dtype=float32]

• Coordinates: (0)
• Indexes: (0)
• Attributes: (9)

  long_name :

  Sea temperature in-situ ITS-90 scale

  standard_name :

  sea_water_temperature

  units :

  degree_Celsius

  valid_min :

  -2.5

  valid_max :

  40.0

  C_format :

  %9.3f

  FORTRAN_format :

  F9.3

  resolution :

  0.001

  casted :

  1

The core-Argo profile files contain the core parameters provided by a float: pressure, temperature, salinity, conductivity (PRES, TEMP, PSAL, CNDC).

Now, let’s see how this argopy data set works as a xarray, and it easy to plot any data. Let’s begin ploting the first two profiles:

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

#Temperature
ax[0].plot(apDS.TEMP[0,:],-apDS.PRES[0,:],'ro',label='N_PROF=0 D Fetcher')
ax[0].plot(apDS.TEMP[1,:],-apDS.PRES[1,:],'bo',label='N_PROF=1 A Fetcher')
ax[0].set_title(apDS['TEMP'].attrs['long_name'])
ax[0].set_ylabel(apDS['PRES'].attrs['long_name'])
ax[0].grid()
ax[0].legend();

ax[1].plot(apDS.PSAL[0,:],-apDS.PRES[0],'ro',label='N_PROF=0 D Fetcher')
ax[1].plot(apDS.PSAL[1,:],-apDS.PRES[1],'bo',label='N_PROF=1 A Fetcher')
ax[1].set_title(apDS['TEMP'].attrs['long_name'])
ax[1].grid()
ax[1].legend();

and of course the locations of these two profiles and the rest of them:

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

ax.plot(apDS.LONGITUDE[0],apDS.LATITUDE[0],'ks',markersize=10,label='001D N_PROF=0 Descending')
ax.plot(apDS.LONGITUDE[1],apDS.LATITUDE[1],'bs',markersize=10,label='001 N_PROF=0 Ascending')
ax.plot(apDS.LONGITUDE[2:],apDS.LATITUDE[2:],'bo',label='rest of the proiles')
ax.grid()
ax.legend();

or using the plotting routines of argopy, easyly we can plot the full trayectory

scatter_map(apDS, set_global=False);

/Users/pvb/miniconda3/envs/AOS/lib/python3.13/site-packages/argopy/plot/plot.py:489: UserWarning: More than one N_LEVELS found in this dataset, scatter_map will use the first level only
  warnings.warn(

argopy is powerfull with continous updates, an de refer to the argopy Documentation for a more detailled explanation of its capabilities.