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Overview

Fathom data is made available by layer. Each layer constitutes a particular data metric for a particular set of dimensions (or descriptors). The dimensions vary depending on what the data represents e.g. flood depths, risk scores, elevation.

Each layer is uniquely defined by its corresponding Layer ID. This is a string defined as follows:

Model-Resolution-Offset-[“1in”ReturnPeriod]-Type-[Defences]-Metric-[Year]-[{“dT”DeltaT, ClimateScenario}]-[“PERCENTILE”Percentile]-Version

[ ] = optional
{ } = choice
“” = literal value

Model - Fathom product from which the layer originates e.g. GLOBAL, UK

Resolution - The horizontal resolution of the layer in arc seconds e.g. 1ARCSEC, 1_3ARCSEC

Offset - Describes the translation direction of any offset of the tile lower left corner relative to the tile name. The offset amount is always 1/7200°. For example, NW_OFFSET means that the bottom left corner of the n00e000 tile is at lon=-1/7200, lat=1/7200. E.g. NW_OFFSET, 00_OFFSET

ReturnPeriod - The frequency of flooding defined by the average time (in years) between the occurrence of a given event e.g. 50, 1000

Type - The type of flooding e.g. PLUVIAL, COASTAL

Defences - The defence state of the flood type e.g. DEFENDED, UNDEFENDED

Metric - The risk metric defined by the layer e.g. DEPTH, RISK_CATEGORY

Year - A year defining part of a climate scenario. Note, selection of a particular year provides data representing the impact of climate change in a 21-year period centred on that year; it does not reflect internal variability for any specific year. e.g. 2020, 2050

DeltaT - Change in global mean surface temperature in °C compared to pre-industrial (1850 – 1900) defining part of a climate scenario. Values must contain two decimal places e.g. dT1.25, dT3.00

ClimateScenario - Models representing different greenhouse gas emissions pathways defining part of a climate scenario e.g. SSP2_4.5, NGFS_CP

Percentile - Represents the uncertainty level of the underlying climate models for the chosen climate scenario e.g. PERCENTILE50, PERCENTILE83

Version - Reflects the data version given as vMajor.Minor[.Patch] e.g. v1.1.0, v3.0

Some examples of Layer IDs are:

  • GLOBAL-1ARCSEC-NW_OFFSET-1in100-PLUVIAL-DEFENDED-DEPTH-2020-PERCENTILE50-v3.0
  • GLOBAL-1ARCSEC-NW_OFFSET-1in20-FLUVIAL-UNDEFENDED-DEPTH-2030-SSP2_4.5-PERCENTILE50-v3.0
  • UK-1_3ARCSEC-00_OFFSET-1in100-FLUVIAL-DEFENDED-DEPTH-2000-PERCENTILE50-v1.1.0