Slot: Missing Value Sentinel (missing_value_sentinel)
The stored value that means "missing" in the source product's files, verbatim, e.g. 32767 (gridMET _FillValue) or -9999 (Daymet nodata). Complements missing_data_handling_method: the policy slot says how gaps were handled, this says which number encodes a gap.
Tier: optional
Why this slot matters
A sentinel read as data is a catastrophic outlier (−9999 °C) or a silent bias (32767 packed); anyone touching the source files rather than the cleaned companion file needs to know which value to mask.
In plain terms
Datasets mark holes with an agreed impossible number, like −9999. If software doesn't know the marker, it will average it in as if it were a real reading. This field records the marker.
URI: envar:slot/missing_value_sentinel
Applicable Classes
| Name |
Description |
Modifies Slot |
| Uncertainty |
Uncertainty and quality character of a value series: per-value uncertainty ty... |
no |
Properties
Type and Range
Cardinality and Requirements
Examples
- Added after the reverse gap survey (docs/reverse-gap-survey.md, 2026-07): two pipelines surfaced the same field independently — the Amadeus THREDDS metadata declares
_FillValue/missing_value 32767, and GAIA's ETL descriptor registers nodata: [float4, -9999]. Neither number had a home: missing_data_handling_method records policy, not the sentinel, and a consumer re-reading the source grid needs the number itself. Kept as a string so non-numeric sentinels (NaN, empty string) stay representable.
See Also
Annotations
| property |
value |
| tier |
optional |
| justification |
A sentinel read as data is a catastrophic outlier (−9999 °C) or a silent bias (32767 packed); anyone touching the source files rather than the cleaned companion file needs to know which value to mask. |
| explanation |
Datasets mark holes with an agreed impossible number, like −9999. If software doesn't know the marker, it will average it in as if it were a real reading. This field records the marker. |
Schema Source
Mappings
| Mapping Type |
Mapped Value |
| self |
envar:missing_value_sentinel |
| native |
envar:missing_value_sentinel |
LinkML Source
name: missing_value_sentinel
annotations:
tier:
tag: tier
value: optional
justification:
tag: justification
value: A sentinel read as data is a catastrophic outlier (−9999 °C) or a silent
bias (32767 packed); anyone touching the source files rather than the cleaned
companion file needs to know which value to mask.
explanation:
tag: explanation
value: Datasets mark holes with an agreed impossible number, like −9999. If software
doesn't know the marker, it will average it in as if it were a real reading.
This field records the marker.
description: 'The stored value that means "missing" in the source product''s files,
verbatim, e.g. `32767` (gridMET `_FillValue`) or `-9999` (Daymet nodata). Complements
`missing_data_handling_method`: the policy slot says *how* gaps were handled, this
says *which number encodes a gap*.'
title: Missing Value Sentinel
comments:
- 'Added after the reverse gap survey (docs/reverse-gap-survey.md, 2026-07): two pipelines
surfaced the same field independently — the Amadeus THREDDS metadata declares `_FillValue`/`missing_value`
32767, and GAIA''s ETL descriptor registers `nodata: [float4, -9999]`. Neither number
had a home: `missing_data_handling_method` records policy, not the sentinel, and
a consumer re-reading the source grid needs the number itself. Kept as a string
so non-numeric sentinels (`NaN`, empty string) stay representable.'
examples:
- value: '32767'
description: gridMET tmmx `_FillValue` / `missing_value` (packed int16)
- value: '-9999'
description: Daymet nodata sentinel as registered in the GAIA catalog
from_schema: https://w3id.org/linkml/microschemas/envar
see_also:
- https://cfconventions.org/cf-conventions/cf-conventions.html#missing-data
rank: 1000
domain_of:
- Uncertainty
range: string