Keyword Glossary

G

glacial mass balance
the net change in a glacier's mass over a specific period, typically a year, representing the difference between accumulation (snow and ice gain) and ablation (melting and loss of ice). the net change in a glacier's mass over a specific period, typically a year, representing the difference between accumulation (snow and ice gain) and ablation (melting and loss of ice). Read More
glacier runoff
the water that flows from a glacier, resulting from the melting of ice and snow, or from rainfall on the glacier's surface. the water that flows from a glacier, resulting from the melting of ice and snow, or from rainfall on the glacier's surface. Read More
Global Infrastructure Risk Model and Resilience Index (GIRI)
a comprehensive, publicly available tool that assesses the financial risks associated with major hazards (earthquakes, tsunamis, floods, etc.) across global infrastructure sectors. a comprehensive, publicly available tool that assesses the financial risks associated with major hazards (earthquakes, tsunamis, floods, etc.) across global infrastructure sectors. Read More

H

Heating degree days (HD
Energy consumption in cold environments depends on the excess of temperature below a given threshold, where heating is required. HDD is an index which uses the mean, maximum and minimum daily temperature.
Units: degree-days Energy consumption in cold environments depends on the excess of temperature below a given threshold, where heating is required. HDD is an index which uses the mean, maximum and minimum daily… Read More

M

Maximum 1-day precipitation (RX1day)
Maximum 1-day precipitation amount. Units: mm Maximum 1-day precipitation amount. Units: mm Read More
Maximum 5-day precipitation (RX5day)
Maximum 5-day precipitation amount. Units: mm Maximum 5-day precipitation amount. Units: mm Read More
Maximum of maximum temperatures (TXx)
Maximum of daily maximum temperature.
Units: degree Celsius Maximum of daily maximum temperature.
Units: degree Celsius Read More
Maximum temperature (TX)
Mean of daily maximum temperature.
Units: degree Celsius Mean of daily maximum temperature.
Units: degree Celsius Read More
Mean Temperature (T)
Mean near-surface air temperature.
Units: degree Celsius Mean near-surface air temperature.
Units: degree Celsius Read More
MERIT Hydro - Hydrologically Adjusted Elevations
High-resolution raster hydrography maps are a fundamental data source for many geoscience applications. Here we introduce MERIT Hydro, a new global flow direction map at 3-arc sec resolution (~90 m at the equator) derived from the latest elevation data (MERIT DEM) and water body data sets (G1WBM, Global Surface Water Occurrence, and OpenStreetMap). We developed a new algorithm to extract river networks near automatically by separating actual inland basins from dummy depressions caused by the errors in input elevation data. After a minimum amount of hand editing, the constructed hydrography map shows good agreement with existing quality-controlled river network data sets in terms of flow accumulation area and river basin shape. The location of river streamlines was realistically aligned with existing satellite-based global river channel data. Relative error in the drainage area was <0.05 for 90% of Global Runoff Data Center (GRDC) gauges, confirming the accuracy of the delineated global river networks. Discrepancies in flow accumulation area were found mostly in arid river basins containing depressions that are occasionally connected at high water levels and thus resulting in uncertain watershed boundaries. MERIT Hydro improves on existing global hydrography data sets in terms of spatial coverage (between N90 and S60) and representation of small streams, mainly due to increased availability of high-quality baseline geospatial data sets. The new flow direction and flow accumulation maps, along with accompanying supplementary layers on hydrologically adjusted elevation and channel width, will advance geoscience studies related to river hydrology at both global and local scales. High-resolution raster hydrography maps are a fundamental data source for many geoscience applications. Here we introduce MERIT Hydro, a new global flow direction map at 3-arc sec resolution (~… Read More