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Dataset Title:	[Open cell and single-step titration method comparison] - Open cell and single- step method for total alkalinity titrations from samples collected on R/V Mirai cruises MR23-06C and MR23-07 in the North Pacific and Western Arctic from September to November 2023 (US GEOTRACES GP17-OCE and GP17-ANT: Inorganic Carbon Cycling in the South Pacific and Southern Oceans by Direct Measurement)
Institution:	BCO-DMO (Dataset ID: bcodmo_dataset_957527_v1)
Range:	longitude = -174.8726 to 179.4858°E, latitude = 27.5003 to 77.0399°N, time = 2023-09-07T21:11:00Z to 2023-11-01T03:38:00Z
Information:	Summary \| License \| FGDC \| ISO 19115 \| Metadata \| Background \| Data Access Form \| Files

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The Dataset Attribute Structure (.das) for this Dataset

Attributes {
 s {
  Cruise {
    String long_name "Cruise";
    String units "unitless";
  }
  sample_ID {
    Int32 actual_range 1100, 70136;
    String long_name "Sample_id";
    String units "unitless";
  }
  Station {
    Int32 actual_range 1, 70;
    String long_name "Station";
    String units "unitless";
  }
  Cast {
    Int32 actual_range 1, 3;
    String long_name "Cast";
    String units "unitless";
  }
  NiskinBottle_No {
    Int32 actual_range 0, 36;
    String long_name "Niskinbottle_no";
    String units "unitless";
  }
  Date {
    String long_name "Date";
    String units "unitless";
  }
  time_unitless {
    String long_name "Time";
    String units "unitless";
  }
  time {
    String _CoordinateAxisType "Time";
    Float64 actual_range 1.69412106e+9, 1.69880988e+9;
    String axis "T";
    String ioos_category "Time";
    String long_name "Iso_datetime_utc";
    String standard_name "time";
    String time_origin "01-JAN-1970 00:00:00";
    String units "seconds since 1970-01-01T00:00:00Z";
  }
  latitude {
    String _CoordinateAxisType "Lat";
    Float32 actual_range 27.5003, 77.0399;
    String axis "Y";
    String ioos_category "Location";
    String long_name "Latitude";
    String standard_name "latitude";
    String units "degrees_north";
  }
  longitude {
    String _CoordinateAxisType "Lon";
    Float32 actual_range -174.8726, 179.4858;
    String axis "X";
    String ioos_category "Location";
    String long_name "Longitude";
    String standard_name "longitude";
    String units "degrees_east";
  }
  CTD_Salinity {
    Float32 actual_range 28.8814, 35.4799;
    String long_name "Ctd_salinity";
    String units "unitless";
  }
  CTD_Salinity_flag {
    Int32 actual_range 2, 9;
    String long_name "Ctd_salinity_flag";
    String units "unitless";
  }
  Bottle_Salinity {
    Float32 actual_range 24.1627, 35.474;
    String long_name "Bottle_salinity";
    String units "unitless";
  }
  Bot_Sal_flag {
    Int32 actual_range 2, 9;
    String long_name "Bot_sal_flag";
    String units "unitless";
  }
  CTD_Pressure {
    Float32 actual_range 5.0, 6137.2;
    String long_name "Ctd_pressure";
    String units "decibars (db)";
  }
  Total_Alkalinity_Single_Step_method {
    Float32 actual_range 1791.2, 2438.3;
    String long_name "Total_alkalinity_single_step_method";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  Total_Alkalinity_Single_Step_Method_flag {
    Int32 actual_range 2, 6;
    String long_name "Total_alkalinity_single_step_method_flag";
    String units "unitless";
  }
  Total_Alkalinity_Open_Cell_Method {
    Float32 actual_range 1788.236, 2436.068;
    String long_name "Total_alkalinity_open_cell_method";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  Total_Alkalinity_Open_Cell_Method_Flag {
    Int32 actual_range 2, 5;
    String long_name "Total_alkalinity_open_cell_method_flag";
    String units "unitless";
  }
  Ship_DIC {
    Float32 actual_range 1740.5, 2393.9;
    String long_name "Ship_dic";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  Ship_DIC_flag {
    Int32 actual_range 2, 6;
    String long_name "Ship_dic_flag";
    String units "unitless";
  }
  Lab_DIC {
    Float32 actual_range 1734.5, 2397.5;
    String long_name "Lab_dic";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  Lab_DIC_analytical_flag {
    Int32 actual_range 2, 4;
    String long_name "Lab_dic_analytical_flag";
    String units "unitless";
  }
  Lab_DIC_Storage_flag {
    Int32 actual_range 2, 4;
    String long_name "Lab_dic_storage_flag";
    String units "unitless";
  }
  Ship_pHt {
    Float32 actual_range 7.2135, 8.0449;
    String long_name "Ship_pht";
    String units "total scale";
  }
  Ship_pHt_flag {
    Int32 actual_range 2, 9;
    String long_name "Ship_pht_flag";
    String units "unitless";
  }
  Ship_pH_Temp {
    Int32 actual_range 25, 25;
    String long_name "Ship_ph_temp";
    String units "degrees Celsius";
  }
  Lab_pHt {
    Float32 actual_range 7.2712, 8.1372;
    String long_name "Lab_pht";
    String units "total scale";
  }
  Lab_pHt_analytical_flag {
    Int32 actual_range 2, 9;
    String long_name "Lab_pht_analytical_flag";
    String units "unitless";
  }
  Lab_pHt_storage_flag {
    Int32 actual_range 2, 9;
    String long_name "Lab_pht_storage_flag";
    String units "unitless";
  }
  Lab_pHt_temp {
    Int32 actual_range 20, 20;
    String long_name "Lab_pht_temp";
    String units "degrees Celsius";
  }
  CTDTEMP {
    Float32 actual_range -1.6626, 26.5914;
    String long_name "Ctdtemp";
    String units "degrees Celsius";
  }
  CTDTEMP_Flag {
    Int32 actual_range 2, 9;
    String long_name "Ctdtemp_flag";
    String units "unitless";
  }
  O2 {
    Float32 actual_range 14.53, 449.44;
    String long_name "O2";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  O2_flag {
    Int32 actual_range 2, 9;
    String long_name "O2_flag";
    String units "unitless";
  }
  DOC {
    Float32 actual_range 34.2, 76.8;
    String long_name "Doc";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  DOC_flag {
    Int32 actual_range 2, 9;
    String long_name "Doc_flag";
    String units "unitless";
  }
  NO3 {
    Float32 actual_range -0.02, 44.61;
    String long_name "No3";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  NO3_flag {
    Int32 actual_range 2, 9;
    String long_name "No3_flag";
    String units "unitless";
  }
  NO2 {
    Float32 actual_range 0.0, 0.33;
    String long_name "No2";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  NO2_flag {
    Int32 actual_range 2, 9;
    String long_name "No2_flag";
    String units "unitless";
  }
  Si {
    Float32 actual_range 1.09, 234.28;
    String long_name "Si";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  Si_flag {
    Int32 actual_range 2, 9;
    String long_name "Si_flag";
    String units "unitless";
  }
  PO4 {
    Float32 actual_range -0.003, 3.169;
    String long_name "Po4";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  PO4_flag {
    Int32 actual_range 2, 9;
    String long_name "Po4_flag";
    String units "unitless";
  }
  NH4 {
    Float32 actual_range -0.01, 7.58;
    String long_name "Nh4";
    String units "micromoles per kilogram of seawater (umol/kg_sw)";
  }
  NH4_flag {
    Int32 actual_range 2, 9;
    String long_name "Nh4_flag";
    String units "unitless";
  }
  fDOM {
    Float32 actual_range 0.001, 0.016;
    String long_name "Fdom";
    String units "RU";
  }
  fDOM_flag {
    Int32 actual_range 2, 9;
    String long_name "Fdom_flag";
    String units "unitless";
  }
 }
  NC_GLOBAL {
    String cdm_data_type "Other";
    String Conventions "COARDS, CF-1.6, ACDD-1.3";
    String creator_email "info@bco-dmo.org";
    String creator_name "BCO-DMO";
    String creator_url "https://www.bco-dmo.org/";
    String defaultDataQuery "&amp;time&lt;now";
    String doi "10.26008/1912/bco-dmo.957527.1";
    Float64 Easternmost_Easting 179.4858;
    Float64 geospatial_lat_max 77.0399;
    Float64 geospatial_lat_min 27.5003;
    String geospatial_lat_units "degrees_north";
    Float64 geospatial_lon_max 179.4858;
    Float64 geospatial_lon_min -174.8726;
    String geospatial_lon_units "degrees_east";
    String history 
"2025-05-12T13:07:40Z (local files)
2025-05-12T13:07:40Z https://erddap.bco-dmo.org/tabledap/bcodmo_dataset_957527_v1.das";
    String infoUrl "https://osprey.bco-dmo.org/dataset/957527";
    String institution "BCO-DMO";
    String license 
"The data may be used and redistributed for free but is not intended
for legal use, since it may contain inaccuracies. Neither the data
Contributor, ERD, NOAA, nor the United States Government, nor any
of their employees or contractors, makes any warranty, express or
implied, including warranties of merchantability and fitness for a
particular purpose, or assumes any legal liability for the accuracy,
completeness, or usefulness, of this information.";
    Float64 Northernmost_Northing 77.0399;
    String sourceUrl "(local files)";
    Float64 Southernmost_Northing 27.5003;
    String summary "Duplicate samples were collected for total alkalinity on two cruises in 2023 aboard the R/V Mirai (MR23-06C and MR23-07) in order to compare two different methods of total alkalinity titrations: the open cell with non-linear least squares fitting and single step with spectrophotometric endpoint detection. Measurements of dissolved inorganic carbon and pH on the total scale were also made as quality control checks. GLODAPv2 hinted at a potential offset between laboratories in the Pacific Ocean. We hypothesized that if non-negligible amounts of organic alkalinity were present, the different methods could be titrating different amounts leading to differences between the methods. The results show that any offset is within the uncertainty of the analytical precision and presence of organic alkalinity in open ocean waters remains inconclusive.";
    String time_coverage_end "2023-11-01T03:38:00Z";
    String time_coverage_start "2023-09-07T21:11:00Z";
    String title "[Open cell and single-step titration method comparison] - Open cell and single-step method for total alkalinity titrations from samples collected on R/V Mirai cruises MR23-06C and MR23-07 in the North Pacific and Western Arctic from September to November 2023 (US GEOTRACES GP17-OCE and GP17-ANT: Inorganic Carbon Cycling in the South Pacific and Southern Oceans by Direct Measurement)";
    Float64 Westernmost_Easting -174.8726;
  }
}

Using tabledap to Request Data and Graphs from Tabular Datasets

tabledap lets you request a data subset, a graph, or a map from a tabular dataset (for example, buoy data), via a specially formed URL. tabledap uses the OPeNDAP (external link)

Data Access Protocol (DAP) (external link)

and its selection constraints (external link)

The URL specifies what you want: the dataset, a description of the graph or the subset of the data, and the file type for the response.

(easy) You can get data by using the dataset's Data Access Form or Subset form. They make the URL for you.
(easy) You can make a graph or map by using the dataset's Make A Graph form. It makes the URL for you.
(not hard) You can bypass the forms and get the data or make a graph or map by generating the URL by hand or with a computer program or script.

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https://coastwatch.pfeg.noaa.gov/erddap/tabledap/datasetID.fileType{?query}
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https://coastwatch.pfeg.noaa.gov/erddap/tabledap/pmelTaoDySst.htmlTable?longitude,latitude,time,station,wmo_platform_code,T_25&time>=2015-05-23T12:00:00Z&time<=2015-05-31T12:00:00Z
Thus, the query is often a comma-separated list of desired variable names, followed by a collection of constraints (e.g., variable<value), each preceded by '&' (which is interpreted as "AND").

For details, see the tabledap Documentation.

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