.. _hydroland_data_description: Data Description ================ This page describes the HydroLand output variables and derived indicators, their units and conventions, the spatial and temporal coverage, and the file formats and naming conventions. Output variables ---------------- HydroLand produces two families of gridded NetCDF output files. The `mesoscale Hydrologic Model (mHM) `_ simulates land-surface hydrology, including soil water storage, evapotranspiration, and runoff generation. The `multiscale Routing Model (mRM) `_ routes the simulated runoff through the river network to produce routed river discharge. Two settings determine how time appears in HydroLand output files. The run frequency controls how often HydroLand is executed and packaged (``day`` or ``month``). The output time step controls the temporal resolution written inside the files (``daily`` or ``hourly``), depending on the incoming OPA data and the HydroLand configuration. For example, a monthly run can write one monthly file containing daily or hourly time steps, while a daily run writes a one-day file with daily or hourly time steps. mHM flux and state files ^^^^^^^^^^^^^^^^^^^^^^^^^ These files contain gridded land-surface states and fluxes produced by mHM at the configured output time step. They describe how water is stored in the soil, returned to the atmosphere, and generated as runoff before routing. .. list-table:: :header-rows: 1 :widths: 30 50 20 * - Variable - Description - Unit * - ``SWC_L01``, ``SWC_L02``, ``SWC_L03`` - Soil water content (3 layers) - mm * - ``aET`` - Actual evapotranspiration - mm day⁻¹ * - ``Q`` - Total runoff - mm day⁻¹ mRM routing files ^^^^^^^^^^^^^^^^^ These files contain gridded routed river discharge produced by mRM from the mHM runoff output. They follow the same run frequency and output time step as the corresponding HydroLand run. .. list-table:: :header-rows: 1 :widths: 30 50 20 * - Variable - Description - Unit * - ``Qrouted`` - Routed river discharge - m³ s⁻¹ Indicator products ^^^^^^^^^^^^^^^^^^ Indicator files are period-summary products derived from the mHM and mRM outputs. They are not continuous flux files; they summarise flood, drought, aridity, and soil-moisture conditions over the supplied historical or projection period. .. list-table:: :header-rows: 1 :widths: 30 50 20 * - Indicator - Description - Output unit * - HydroLand aridity indicator - Ratio of mean annual actual ET to mean annual precipitation - dimensionless * - Soil moisture deficit - Time-mean deficit below the fitted long-term soil moisture trend - mm * - Discharge percentiles - p1, p5, p10, p90, p95, p99 threshold values from routed discharge - m³ s⁻¹ * - Flood/drought event count - Number of distinct events above/below the selected percentile threshold - count * - Flood/drought duration - Total number of event time steps - days or hours * - Flood/drought intensity - Accumulated exceedance or deficit relative to the threshold - m³ s⁻¹ × time step The algorithms behind the indicator products are described in :ref:`hydroland_technical_documentation`. Spatial coverage and resolution ------------------------------- - **Domain:** global (land surface). - **Resolutions:** ``0.1°`` (≈ 10 km) and ``0.05°`` (≈ 5 km). - **mRM routing subdomains:** 53 (``0.1°`` setup) or 26 (``0.05°`` setup) basin-based partitions, merged into a single global product. Temporal coverage and resolution -------------------------------- - **Period:** historical (1990–2014) and projection (2015–2049). - **Run frequency:** ``day`` or ``month``, controlling whether HydroLand writes one-day files or files covering a full month. - **Output time step:** ``daily`` or ``hourly``, controlling the temporal resolution of the data stored inside each file. File formats and naming conventions ----------------------------------- All outputs are NetCDF (``.nc``) with CF-compliant metadata. Attributes are inherited from the driving climate forcing (``activity``, ``experiment``, ``generation``, ``model``, ``realization``, ``stream``, ``resolution``) together with the global attribute ``application = "HydroLand"``. mHM flux files:: YYYY_MM_DD_to_YYYY_MM_DD_mHM_Fluxes_States.nc (daily) YYYY_MM_DD_T00_00_to_YYYY_MM_DD_T23_00_mHM_Fluxes_States.nc (hourly) mRM flux files:: YYYY_MM_DD_to_YYYY_MM_DD_mRM_Fluxes_States.nc YYYY_MM_DD_T00_00_to_YYYY_MM_DD_T23_00_mRM_Fluxes_States.nc Indicator files:: YYYY_YYYY_aridity_index.nc YYYY_YYYY__percentile_discharge_indicators.nc (e.g. 90th, 5th) HydroLand output is published on the DestinE Data Lake under the collection identifier `EO.UFZ.DAT.HYDROLAND `_. Different model experiments appear as separate items, so users can identify the experiment, period, and realization they need. Further access notes and STAC metadata conventions are described in :ref:`hydroland_examples`.