Movable field gonio-spectrometer "ManTIS Observatory"
for easy ground truthing of satellite measurements
Reflection of sunlight from vegetated earth surface is highly variable. For example, it depends on vegetation type and soil properties. On this basis space-born measurements of the electromagnetic spectrum of the earth surface allow for an efficient mapping of vegetation types, large scale environmental changes, and for the assessment of matter fluxes (e.g. greenhouse gas emissions) by remote sensing techniques. However, in order to calibrate satellite observation with the specific type of vegetation, the direction-dependent reflectance of light has to be determined as a function of the sun’s irradiation angle as well as the position of the optical measuring device. Satellite systems with large foot print and sensors with pointing possibilities typically do not account for this anisotropy yet. In order to improve accuracy, field measurements are needed for validation (ground truthing). The goniometer developed at the Alfred Wegener Institute is particularly designed for field use in difficult terrains: low weight and weatherproof parts help to ease the investigation of direction-dependent reflectance of sunlight even in remote areas.
- total weight: 21,5 kg
- full circle recording with an accuracy of 1°
- ± 30° off nadir;accuracy 1°
- time for a complete series of 63 measurement points:20 min
- constantly centered observation;
- sensor height : 2 m
The manual transportable instrument system for hemispheric multiangular observations called "ManTIS Observatory" was successfully deployed on several field campaigns to permafrost and tundra landscapes in order to prepare hyper-spectral measurements for the “EnMAP” satellite mission launched in 2015. For instance, ManTIS is used to derive algorithms for the simulation and normalisation of off-nadir measurements in cooperation with the EnMAP team.
The instrument was designed to be manufactured of simple and low cost materials and for easy use with robust mechanics and resistance against moisture and cold conditions.
A German patent DE102011117713B4 was granted. Applications are pending in US and CA. Several exemplars of prototypes have been manufactured and were successfully used under harsh conditions.
Marcel Buchhorn, Alfred Wegener Institute, Telegrafenberg A43, 14473 Potsdam; email@example.com; Tel: ++49(0)331-288-2218 or the Technology Transfer Office (see below)