Details of Award
NERC Reference : NE/H002235/1
A hyperspectral skydome sensor for atmospheric monitoring
Grant Award
- Principal Investigator:
- Professor EJ Milton, University of Southampton, School of Geography
- Grant held at:
- University of Southampton, School of Geography
- Science Area:
- Terrestrial
- Marine
- Freshwater
- Earth
- Atmospheric
- Overall Classification:
- Atmospheric
- ENRIs:
- Pollution and Waste
- Global Change
- Environmental Risks and Hazards
- Science Topics:
- Environment & Health
- Land - Atmosphere Interactions
- Boundary Layer Meteorology
- Tropospheric Processes
- Abstract:
- We propose a new instrument to measure the angular distribution of spectral sky radiance for use in ground and airborne campaigns focused on aerosol and trace gas studies, including the validation of data from Earth observing satellite sensors. Airborne survey plays an important role in determining the quantitative composition of the atmosphere, and is especially useful as means of measuring and monitoring the horizontal and vertical distribution of aerosols and particulates. The proposed approach will improve the abilities provided by currently available radiometric and photometric instruments in three ways. First, the new instrument has no moving parts, which will enhance its reliability, especially for unattended operation or use in hostile environments. Second, the instrument will provide simultaneous hyperspectral measurements of sky radiance over the full sky dome, which will mean that we can estimate the angular distribution of diffuse radiance at high temporal frequency regardless of aircraft motion. Third, the new instrument will allow retrieval of direct-beam solar radiance by virtue of its novel design and advanced data processing algorithm. Data from the instrument will be of immediate benefit to those interested in the atmospheric correction of EO data, but the advanced features of the instrument mean that it will also provide significant benefits to the wider science community, such as through improvements to existing sky radiance models, especially at the aureole around the Sun and the horizontal annulus close to the horizon, and better understanding of the relationship between sky radiance distribution and surface bidirectional reflectance measurements. Our proposed approach is to use a bundle of fibre optic cables fixed at evenly distributed points on a hemispherical dome with a cosine diffuser at its zenith. The fibre optic bundle is linked in a relatively compact and modular design rack-mounted multichannel grating spectrometer that permits portable outdoor use and easier integration on a wider range of aircraft. The spectrometer is capable of upgrade by relatively straightforward substitution (or addition) of more specialised spectrometers in future versions. Successful implementation of this approach requires overcoming the following technological challenges, 1. Determining the optimal angular spacing between fibres over the sky hemisphere. 2. Acquiring sufficiently accurate sky scans within 1 second under all weather conditions. 3. Maintaining a relative calibration accuracy better than than 3% over the period of a flight season (~6 months). 4. Ensuring that irradiance obtained by integration of sky radiance from the angular radiance probes is within 1% of the true value. 5. Ensuring that geometric registration of the data points is better than 1 degree. To demonstrate the feasibility of this approach, we have extensively tested an airborne upward-looking cosine diffuser currently operated by NERC ARSF in both laboratory and field campaigns, and used data from this sensor in conjunction with a sky radiance distribution model. These tests and our experience with AERONET and other sunphotometers have demonstrated that our approach can overcome the above challenges. The proposed research involves a three month Critical Design Review (CDR)/Algorithm Development phase, followed by development and ground-testing over a six-month period, then aircraft integration and flight testing within the final three-months. Key milestones include: (1) CDR guidelines and (2) Publication of Algorithm Theoretical Basis Document (ATBD), (3) Procurement of a multichannel spectrometer and components, (4) Development of operating software, (5) System integration and testing, (6) System calibration, (7) Full system testing on ground, (8) Aircraft integration, (9) Flight test program, and (10) Improvement and preparation for future missions, including documentation.
- NERC Reference:
- NE/H002235/1
- Grant Stage:
- Completed
- Scheme:
- Directed (Research Programmes)
- Grant Status:
- Closed
- Programme:
- Tech Proof of Concept
This grant award has a total value of £155,658
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Exception - Equipment | Indirect - Indirect Costs | DA - Investigators | DA - Estate Costs | DI - Equipment | DI - Staff | DI - T&S |
|---|---|---|---|---|---|---|---|
| £7,012 | £46,363 | £32,061 | £3,526 | £12,171 | £10,000 | £38,600 | £5,924 |
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