High Altitude and LOng Range Research Aircraft | GEOHALO

This figure shows the results of the evaluation of gravity measurements taken on the German high-altitude research aircraft HALO over Italy in June 2013. The figure consists of four individual images or plots. At the top right is a map showing Italy with its adjacent seas (Adriatic and Mediterranean). The flight profiles flown with the HALO aircraft are shown on this map. One of these profiles is marked. It starts near Venice and leads over the Adriatic and Calabria to the Mediterranean east of Sicily. For this flight profile, the gravity variations obtained along this track are shown as a function of geographical latitude in a plot on the left-hand side of the figure. They vary between approx. +60 and -60 mGal. For comparison, the values of a global gravity field model (EIGEN-6C4) are drawn as a second curve below. This gravity field model was calculated from satellite data and earlier terrestrial gravity measurements. It shows a high degree of agreement with the gravity data measured on HALO. A third curve drawn below shows the variations of the earth's surface above land (topography) and below water (bathymetry) along the flown track. It varies between about -3500 and +1000 meters. Bottom right and left, the map and the plot of gravity variations are shown in the same way for a second flight profile flown approximately one hundred kilometers west, parallel to the first profile.
Results from the analysis of the GEOHALO gravity measurements: The pictures on the left hand side show the gravity variations derived from the Chekan-AM (blue) together with the passed topography and bathymetry along the respective flight tracks (right, yellow). For comparison the values of the global model EIGEN-6C4 are given (green). This model is based on satellite and terrestrial data. (Ch. Förste, GFZ)

The new German research aircraft HALO (High Altitude and LOng Range Research Aircraft) has been purchased by a joint initiative of the German Federal Ministry for Education and Research BMBF, the Max Planck Society, the Helmholtz Association, the state of Bavaria, the Reseach Centre Juelich, the Karlsruhe Institute for Technology KIT and the German Centre for Aeronautics and Space Research DLR. GFZ is partner of the HALO consortium. The German Research Foundation DFG is supporting projects on the HALO aircraft within the DFG High priority program SPP-1294 “Atmospheric and Earth System Research with the High Altitude and Long Range Research Aircraft (HALO)”.

GEOHALO is the first scientific mission done on the HALO aircraft. It comprises an equipment of geophysical and geodetic sensors and has been conducted between June 4th and 12th 2013 in four flights over Italy.

GFZ was involved in the GEOHALO project with the topics "GNSS-Reflectometry", "Geomagnetic Field" and "Gravimetry". Our section was responsible for the Gravimetry. It was the intention to show whether and how an efficient airborne gravity field determination is feasible in wide areas when using a fast aircraft like HALO at higher altitudes. Here, unlike “classical” airborne gravimetry for exploration, the aim is not primarily the highest spatial resolution by flying as low and slow as possible. The task is to map areas where only insufficient or no terrestrial gravity data are available to achieve a resolution which is considerably better as that of satellite-only gravity field models. This is beneficial for the generation of global gravity field models which require a uniform, high spatial resolution for the gravity data over the entire Earth. Hence, future targets for HALO will mainly be areas with bad or sparse terrestrial data and regions which are inaccessibly for terrestrial gravimetry on ground.

The figures below show first comparisons between gravity variations deduced from the HALO measurements and the global gravity field model EIGEN-6C4 which contains satellite and terrestrial gravity data. To remove the high frequency noise of the Chekan measurements and of the GNSS derived vertical kinematic accelerations a low-pass filter with a cut-off wavelength of 200 seconds has been applied. With a flight speed of 425 km/h this results in a spatial resolution of 12 km half-wavelength. This corresponds to the resolution of the model EIGEN-6C4, which can be assumed as very accurate in this area due to the good and dense gravimetrical data included. It’s clearly visible, that HALO coincides very well with EIGEN-6C4.

Project Partners:

  • GFZ, Sections 1.1 “Space Geodetic Techniques” and 2.3 “Geomagnetism“
  • Federal Institute for Geosciences and Natural Resources (BGR), Hannover
  • Eidgenössische Technische Hochschule (ETH), Zurich
  • Institut de Ciències de l’Espai (ICE – CSIC/IEEC), Barcelona
  • German Space Operations Center (DLR-GSOC), Oberpfaffenhofen

Project Duration:

  • 2008 – 2012

Funding: 

Project related publications:

  •  Schaller, T., Scheinert, M., Barthelmes, F., Förste, C. (2019): Inversion of GEOHALO aerogravimetry to infer ocean bottom topography: application to the Tyrrhenian, Ionian and Adriatic seas. - Geophysical Journal International, 216, 2, 840-850.
    https://doi.org/10.1093/gji/ggy456
  • Lu, B., Barthelmes, F., Petrovic, S., Förste, C., Flechtner, F., Luo, Z., He, K., Li, M. (2017): Airborne Gravimetry of GEOHALO Mission: Data Processing and Gravity Field Modeling.Journal of Geophysical Research, 122, 12, 10,586-10,604.
    https://doi.org/10.1002/2017JB01442
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