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Waterbody temperature

Image credit: Servir (USAID/NASA)

PRODUCT DESCRIPTION

Category

Component products

Water Quantity & Quality

N/A

Uses

  • Surface geology mapping - mapping geological features
  • Environmental monitoring - baseline historic mapping of environment and ecosystems

Geo-information requirements

  • Water quantity identification
  • Water quality identification

Description

Water body temperature derived from satellite measurements provide information on the temperature of the water close to the surface, or the water “skin”, but no information on the vertical temperature profile of the water body. To derive water surface temperature, a satellite sensor has to measure in the thermal infrared (TIR - emissive) part of the electromagnetic spectrum (between 8 to 14 µm). EO systems with thermal optical sensors are available, such as Landsat and ASTER. Emissive thermal infra-red images typically have lower spatial resolution than corresponding reflective optical images from the same.

Quantitative estimation of temperatures from TIR images requires compensation for absorption by atmospheric gases (water vapour, ozone and carbon dioxide) and upwelling atmospheric emitted radiance. The most common method to compensate for atmospheric effects is usage of radiative transfer models such as MODTRAN. Thermal infrared temperatures may also be affected by surface effects (such as multiple reflection, and sub‑pixel mixing).

Temperature data obtained from satellite sensors and in situ measurements are desirable to understand the thermal processes taking place in water bodies.  Satellite-based monitoring may extend and supplement data that can be obtained from in-situ devices, including automated sensors that may provide data via telemetry. In regions with vast numbers of lakes (e.g., Canada, Alaska) very little prior information may be available in exploration and development areas.

The Sentinel-3 satellite will include the Sea and Land Surface Temperature Radiometer (SLSTR) which is based on Envisat’s (Advanced) Along Track Scanning Radiometers AATSR.

The water body temperature product can deliver temperature calibrated images over lake areas (raster), along with horizontal profile plots and summary reports. Multi-temporal and multi-season characteristics can be evaluated.

Known restrictions / limitations

Temperature calculation may not be possible for small water bodies due to the low spatial resolution of thermal sensors.

Lifecycle stage and demand

Pre-License Exploration

Development

Production

Decommission

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All lifecycle stages:

  • Water body temperature is likely a component of baseline environmental information that may be required in advance of exploration and development in a project area. Temperature data would be valuable along with lake productivity and bathymetry information to enable understanding potential sensitivity of water bodies.
  • Baseline information on water bodies in a project/license area or large region of operations.

Monitoring of water bodies over time to capture seasonal variation in properties.

Geographic coverage and demand

Coverage and demand is global, but focused on locations where access is challenging, or the sheer number of lakes makes baseline data gathering very challenging.

Challenges Addressed

OTM:030  Ecosystem valuation of potential site

HC:2102  Understanding hydrogeology

HC:4109  Understand temporal and spatial extent of usable fish habitat to maintain acceptable levels

PRODUCT SPECIFICATIONS

Input data sources

Optical: HR2, MR1 with thermal infrared bands

Water body temperature estimation requires usage of sensors capable of acquiring data in the thermal part of the spectrum, e.g., Landsat-7, Landsat- 8, Landsat- 5 (archive only). ASTER sensors (since 1999) provide 5 TIR bands with 90 m resolution.

Supporting data: In situ measurements

Spatial resolution and coverage

Spatial resolution: 30–90 m.

The best available spatial resolutions are: 60 m from Landsat-7; 100 m (resampled to 30 m) from Landsat-8; and 90 m for ASTER.

Minimum Mapping Unit (MMU)

The minimum mapping unit is constrained by the minimum size of lakes that can be imaged. For example, from Landsat-7 (60 m), lakes can be monitored for average temperature that are greater than approximately 1.4 ha; however, lake position and extent would need to be delineated from higher resolution imagery, to constrain thermal returns to “on-target” areas.

Accuracy / constraints

Landsat-8: 41 meters circular error, 90-percent confidence.

AVHRR: The validation against in situ observations exhibits biases in the range of −0.4–0.6 K.

Sentinel 3 SLSTR: will allow determining global sea-surface temperature with an accuracy of 0.3K.

Accurate discrimination of land from water pixels and mixed pixels is important. Precise geocoding and ortho-rectification is important especially for the small lakes.

Accuracy assessment approach & quality control measures

Comparison with in-situ measurements.

Frequency / timeliness

Observation frequency: Depending on satellite revisit time (e.g., Landsat8, 16 days). Frequency of historical maps is highly variable depending on the archive.

Timeliness of delivery: Processing can be completed in near real time (< 24 hours) depending on availability of base images.

Availability

Archive and ESA (Sentinel) data available at no charge. Systematic acquisition of Landsat-8 at no charge.

Archived products, including basic archived ASTER data products are available to all users at no cost. Availability may be limited for specific dates.

Delivery / output format

  

Data type:

  • Raster
  • Plots
  • Summary report

File format:

  • Geotiff or client specified raster formats
  • Standard office graphics formats
  • Standard office document formats

Download product sheet.

 

Lead Author:

Hatfield Consultants/SRC

Peer Reviewer:

OTM/GeoVille

Author(s):

Dean, Aleksandrowicz

Document Title:

Waterbody temperature

# of Pages:

4

Circulation:

Internal – Project consortium and science partners

 

External – ESA

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