Time Series Variables¶
Each grid point in the High Resolution Tidal Hindcast stores a one-year
hourly (Alaska) or half-hourly (contiguous U.S.) time series in a parquet
file. The table below describes every column in that file. These are the
variables returned by get_data_at_point and the
us-tidal CLI.
For the single-value summary variables shown in the Atlas (annual mean speed, 95th percentile, etc.), see Atlas Variables.
The full variable reference documents every field in the dataset. The table and metadata below are generated directly from the parquet schema of the downloaded file.
Column names prefixed with vap_ are Value Added Products:
quantities derived from the raw model output (e.g. speed computed from
u/v components, power density from speed). Pass return_metadata=True
to get_data_at_point to receive CF-convention variable and file-level
metadata alongside the DataFrame.
Layered variables span all 10 sigma layers (layer 0 = sea surface, layer 9 = near-seafloor) and are collapsed to a single row.
| Variable | Label | Units |
|---|---|---|
| vap_sea_water_speed_layer_(0–9) | Sea Water Speed | m s-1 |
| vap_water_column_max_sea_water_speed | Depth maximum Sea Water Speed | m s-1 |
| vap_water_column_mean_sea_water_speed | Depth averaged Sea Water Speed | m s-1 |
| vap_sea_water_power_density_layer_(0–9) | Sea Water Power Density | W m-2 |
| vap_water_column_max_sea_water_power_density | Depth maximum Sea Water Power Density | W m-2 |
| vap_water_column_mean_sea_water_power_density | Depth averaged Sea Water Power Density | W m-2 |
| vap_sea_water_to_direction_layer_(0–9) | Sea Water Velocity To Direction | degree |
| vap_water_column_mean_sea_water_to_direction | Depth averaged Sea Water Velocity To Direction | degree |
| vap_surface_elevation | Sea Surface Elevation Relative to Mean Sea Level | m |
| u_layer_(0–9) | Eastward Water Velocity | m s-1 |
| v_layer_(0–9) | Northward Water Velocity | m s-1 |
| vap_sigma_depth_layer_(0–9) | Depth Below Sea Surface at Sigma Levels | m |
| element_corner_1_lat | Nodal Latitude | degrees_north |
| element_corner_1_lon | Nodal Longitude | degrees_east |
| element_corner_2_lat | Nodal Latitude | degrees_north |
| element_corner_2_lon | Nodal Longitude | degrees_east |
| element_corner_3_lat | Nodal Latitude | degrees_north |
| element_corner_3_lon | Nodal Longitude | degrees_east |
| vap_sea_floor_depth | Water Depth from Sea Surface to Seafloor | m |
| vap_water_column_mean_u | Depth averaged Eastward Water Velocity | m s-1 |
| vap_water_column_mean_v | Depth averaged Northward Water Velocity | m s-1 |
| vap_zeta_center | Sea Surface Height at Cell Centers from NAVD88 | m from NAVD88 |
Variable Metadata¶
Each column carries full CF-convention metadata accessible via
return_metadata=True. Here is the complete attribute set for
vap_sea_water_power_density_layer_0 as an example:
_, file_meta, var_meta = tidal.get_data_at_point(lat=lat, lon=lon, return_metadata=True)
pd.DataFrame(var_meta["vap_sea_water_power_density_layer_0"].items(), columns=["Attribute", "Value"])
| | Attribute | Value |
|----|----|----|
| 0 | long_name | Sea Water Power Density |
| 1 | units | W m-2 |
| 2 | grid | fvcom_grid |
| 3 | type | data |
| 4 | mesh | fvcom_mesh |
| 5 | location | face |
| 6 | coverage_content_type | modelResult |
| 7 | additional_processing | Computed using the fluid power density equatio... |
| 8 | computation | sea_water_power_density = 0.5 \* rho \* sea_wate... |
| 9 | input_variables | sea_water_speed (m/s), rho=\`1025.0\` (kg/m³) |
| 10 | citation | Haas, Kevin A., et al. 'Assessment of Energy P... |
Dataset Metadata¶
Each parquet file in this dataset also contains metadata that describes the dataset:
| | Attribute | Value |
|----|----|----|
| 0 | WPTO_HINDCAST_FORMAT_VERSION | 1.0 |
| 1 | WPTO_HINDCAST_METADATA_TYPE | netcdf_compatible |
| 2 | Conventions | CF-1.10, ACDD-1.3, ME Data Pipeline-1.0 |
| 3 | acknowledgement | This work was funded by the U.S. Department of... |
| 4 | code_url | https://github.com/NREL/Marine_Energy_Resource... |
| 5 | code_version | 1.0.0 |
| 6 | creator_country | USA |
| 7 | creator_email | zhaoqing.yang@pnnl.gov |
| 8 | creator_institution | Pacific Northwest National Laboratory (PNNL) |
| 9 | creator_institution_url | https://www.pnnl.gov/ |
| 10 | creator_name | Zhaoqing Yang |
| 11 | creator_sector | gov_federal |
| 12 | creator_state | Washington |
| 13 | creator_type | institution |
| 14 | creator_url | https://www.pnnl.gov/projects/ocean-dynamics-m... |
| 15 | contributor_name | Mithun Deb, Preston Spicer, Taiping Wang, Levi... |
| 16 | contributor_role | author, author, author, author, author, proces... |
| 17 | contributor_role_vocabulary | https://vocab.nerc.ac.uk/collection/G04/current/ |
| 18 | contributor_url | https://www.pnnl.gov, www.nrel.gov |
| 19 | data_level | b1 |
| 20 | dataset_name | wpto_high_res_tidal.ak_cook_inlet.v1.0.0 |
| 21 | datastream | wpto_high_res_tidal.ak_cook_inlet.b1.v1.0.0 |
| 22 | description | High-resolution tidal energy resource hindcas... |
| 23 | featureType | timeSeries |
| 24 | geospatial_lat_units | degrees_north |
| 25 | geospatial_lon_units | degrees_east |
| 26 | geospatial_vertical_origin | geoid |
| 27 | geospatial_vertical_positive | down |
| 28 | geospatial_vertical_units | m |
| 29 | history | Ran by asimms on x1003c2s1b1n1 (OS: Linux, Ker... |
| 30 | id | AK_cook_inlet.wpto_high_res_tidal.v1.0.0 |
| 31 | infoURL | https://www.github.com/nrel/marine_energy_reso... |
| 32 | inputs | \['/kfs2/projects/hindcastra/Tidal/datasets/hig... |
| 33 | keywords | OCEAN TIDES, TIDAL ENERGY, VELOCITY, SPEED, DI... |
| 34 | license | Freely Distributed |
| 35 | naming_authority | gov.nrel.water_power |
| 36 | references | Deb, Mithun, Zhaoqing Yang, and Taiping Wang. ... |
| 37 | temporal | hourly |
| 38 | date_created | 2023-02-07T20:23:00 |
| 39 | date_issued | 2025-11-12 |
| 40 | date_metadata_modified | 2025-11-20T19:46:18.682654+00:00 |
| 41 | date_modified | 2025-11-20T19:46:18.682654+00:00 |
| 42 | processing_level | b1 |
| 43 | product_version | 1.0.0 |
| 44 | program | U.S. Department of Energy (DOE) Office of Ener... |
| 45 | project | High Resolution Tidal Hindcast |
| 46 | summary | High-resolution tidal energy resource hindcas... |
| 47 | publisher_country | USA |
| 48 | publisher_email | michael.lawson@nrel.gov |
| 49 | publisher_institution | National Renewable Energy Laboratory (NREL) |
| 50 | publisher_name | Michael Lawson |
| 51 | publisher_state | Colorado |
| 52 | publisher_type | institution |
| 53 | publisher_url | https://www.nrel.gov |
| 54 | source | FVCOM_4.3.1 |
| 55 | title | High Resolution Tidal Hindcast for Cook Inlet,... |