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830 results on '"Lühr, H."'

201. Thermospheric density structures over the polar regions abserved with CHAMP

Author

Schlegel, K., Lühr, H., St.-Maurice, J., Crowley, G., and Hackert, C.

Subjects
Physics::Space Physics, 550 - Earth sciences
Abstract

We report on the unexpected detection of considerable structure in high latitude thermospheric densities, as derived from an accelerometer onboard the CHAMP satellite. The width of the structures, which can either be maxima or minima, varies between a few hundred km and 2000 km. The amplitudes of these density extrema can reach 50% of ambient. Maxima cluster around 75° (N and S), while minima are found closer to the poles. In a magnetic latitude - magnetic local time frame the maxima are found mainly around the cusp region. Overall, the observed structures somewhat resemble so-called density cells previously found in model calculations. However the models generate their cells around 140-300 km altitude and show little, if any remnant at 400 km or above. This has to be contrasted with the fact that the CHAMP observations were obtained near 430 km altitude. We have explored Joule heating as a possible mechanism for the generation of the structures, at least in density enhancement regions, using Hall currents measured on CHAMP and simultaneous incoherent scatter measurements with EISCAT. However, the electric fields were usually quite small during the period of observation, making the quest for an explanation for the structures all the more challenging.

Published
2005

203. CHAMP: Mission Status & Development

Author

Reigber, C., Schwintzer, P., Lühr, H., Wickert, J., 1.2 Global Geomonitoring and Gravity Field, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, Gravity Field and Gravimetry -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Earth Observing Satellites -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
550 - Earth sciences
Published
2004

214. CHAMP Mission Science Data System Operation and Generation for Scientific Products

Author

Reigber, C., Schwintzer, P., Lühr, H., Massmann, F., Galas, R., Ritschel, B., CeGIT Centre for GeoInformation Technology, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, Earth Observing Satellites -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Gravity Field and Gravimetry -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
550 - Earth sciences
Published
2003

216. Initial results on ionosphere / plasmashere sounding based on GPS data obtained on board CHAMP

Author

Heise, S., Jakowski, N., Wehrenpfenning, A., Reigber, C., Lühr, H., 1.2 Global Geomonitoring and Gravity Field, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Gravity Field and Gravimetry -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
550 - Earth sciences
Published
2003

219. The Swarm Satellite Constellation Application and Research Facility (SCARF) and Swarm data products

Author

Olsen, N., Friis-Christensen, E., Floberghagen, R., Alken, P., Beggan, Ciaran D., Chulliat, A., Doornbos, E., da Encarnação, J. T., Hamilton, Brian, Hulot, G., von den IJssel, J., Kushinov, A., Lesur, V., Lühr, H., Macmillan, Susan, Maus, S., Noja, M., Olsen, P. E. H., Park, J., Plank, G., Püthe, C., Rauberg, J., Ritter, P., Rother, M., Sabaka, T., Schachtschneider, R., Sirol, O., Stolle, C., Thébault, E., Thomson, Alan W.P., Tøffner-Clausen, L., Velímský, J, Vigneron, P., Visser, P. N., Olsen, N., Friis-Christensen, E., Floberghagen, R., Alken, P., Beggan, Ciaran D., Chulliat, A., Doornbos, E., da Encarnação, J. T., Hamilton, Brian, Hulot, G., von den IJssel, J., Kushinov, A., Lesur, V., Lühr, H., Macmillan, Susan, Maus, S., Noja, M., Olsen, P. E. H., Park, J., Plank, G., Püthe, C., Rauberg, J., Ritter, P., Rother, M., Sabaka, T., Schachtschneider, R., Sirol, O., Stolle, C., Thébault, E., Thomson, Alan W.P., Tøffner-Clausen, L., Velímský, J, Vigneron, P., and Visser, P. N.

Abstract

Swarm, a three-satellite constellation to study the dynamics of the Earth's magnetic field and its interactions with the Earth system, is expected to be launched in late 2013. The objective of the Swarm mission is to provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system by improving our understanding of the Earth's interior and environment. In order to derive advanced models of the geomagnetic field (and other higher-level data products) it is necessary to take explicit advantage of the constellation aspect of Swarm. The Swarm SCARF (Satellite Constellation Application and Research Facility) has been established with the goal of deriving Level-2 products by combination of data from the three satellites, and of the various instruments. The present paper describes the Swarm input data products (Level-1b and auxiliary data) used by SCARF, the various processing chains of SCARF, and the Level-2 output data products determined by SCARF.

Published
2013

220. The Swarm Satellite Constellation Application and Research Facility (SCARF) and Swarm data products

Author

Olsen, Nils, Friis-Christensen, Eigil, Floberghagen, R., Alken, P., Beggan, C. D., Chulliat, A., Doornbos, E., Teixeira da Encarnacao, J., Hamilton, B., Hulot, G., van den IJssel, J., Kuvshinov, A., Lesur, V., Lühr, H., Macmillan, S., Maus, S., Noja, M., Olsen, Poul Erik Holmdahl, Park, J., Plank, G., Püthe, C., Rauberg, J., Ritter, P., Rother, M., Sabaka, T. J., Schachtschneider, R., Sirol, O., Stolle, Claudia, Thebault, E., Thomson, A. W. P., Tøffner-Clausen, Lars, Velimsky, J., Vigneron, P., Visser, P. N., Olsen, Nils, Friis-Christensen, Eigil, Floberghagen, R., Alken, P., Beggan, C. D., Chulliat, A., Doornbos, E., Teixeira da Encarnacao, J., Hamilton, B., Hulot, G., van den IJssel, J., Kuvshinov, A., Lesur, V., Lühr, H., Macmillan, S., Maus, S., Noja, M., Olsen, Poul Erik Holmdahl, Park, J., Plank, G., Püthe, C., Rauberg, J., Ritter, P., Rother, M., Sabaka, T. J., Schachtschneider, R., Sirol, O., Stolle, Claudia, Thebault, E., Thomson, A. W. P., Tøffner-Clausen, Lars, Velimsky, J., Vigneron, P., and Visser, P. N.

Abstract

Swarm, a three-satellite constellation to study the dynamics of the Earth's magnetic field and its interactions with the Earth system, is expected to be launched in late 2013. The objective of the Swarm mission is to provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system by improving our understanding of the Earth's interior and environment. In order to derive advanced models of the geomagnetic field (and other higher-level data products) it is necessary to take explicit advantage of the constellation aspect of Swarm. The Swarm SCARF (Satellite Constellation Application and Research Facility) has been established with the goal of deriving Level-2 products by combination of data from the three satellites, and of the various instruments. The present paper describes the Swarm input data products (Level-1b and auxiliary data) used by SCARF, the various processing chains of SCARF, and the Level-2 output data products determined by SCARF.

Published
2013

223. First scalar magnetic anomaly map from CHAMP satellite data indicates weak lithospheric field

Author

Maus, S., Rother, M., Holme, R., Lühr, H., Nils Olsen, and Haak, V.

Subjects
550 - Earth sciences, Physics::Geophysics
Abstract

Satel1ite magnetic anomaly maps derived by different techniques from Magsat/POGO data vary by more than a factor of 2 in the deduced strength of the lithospheric magnetic field. Here, we present a first anomaly map from new CHAMP scalar magnetic field data. After subtracting a recent 0rsted main and external field model, we remove remaining unmodeled large-scale external contributions from 120° track segments by subtracting a best-fitting uniform field. In order to preserve N/S trending features, the data are not filtered along-track. Direct integration of the spherical1y gridded data yields the final degree 14-65 spherical harmonic expansion of the total intensity anomaly at the mean satel1ite altitude of 438 km. Apart from enhanced long wavelength features and a smoother general appearance, our initial map is strikingly similar to one of the lower strength Magsat/POGO maps. INDEX TERMS: 1545 Geomagnetic and Paleomagnetism: Spatial variations (all harmonics and anomalies); 1594 Geomagnetic and Paleomagnetism: Instruments and techniques; 1532 Geomagnetic and Paleomagnetism: Reference fields (regional, global); 2778 Magnetospheric Physics: Ring current potsdam.de/champ for details). Our analysis of scalar data from the first 14 months of the mission provides strong evidence in favor of a relatively weak lithospheric field. The lithospheric magnetic anomaly map exhibits remarkable similarity to the combined Magsat/POGO map of Arkani-Hamed et al. [1994].

Published
2002

225. GPS radio occultation measurements of the ionosphere from CHAMP: Early results

Author

Jakowski, N., Wehrenpfennig, A., Heise, S., Reigber, C., Lühr, H., Grunewaldt, L., Meehan, T.K., 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Earth Observing Satellites -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
Radio Occultation, GPS, CHAMP, 550 - Earth sciences, Ionosphere
Published
2002

226. Sounding of the topside ionosphere/plasmasphere based on GPS measurements from CHAMP: Initial results

Author

Heise, S., Jakowski, N., Wehrenpfennig, A., Reigber, C., Lühr, H., 1.2 Global Geomonitoring and Gravity Field, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Earth Observing Satellites -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
Plasmasphere, GPS, CHAMP, Sounding, 550 - Earth sciences, Ionosphere
Published
2002

229. Low latitude electron temperature observed by the CHAMP satellite

Author

Stolle, Claudia, Truhlik, V., Richards, P., Olsen, Nils, Lühr, H., Stolle, Claudia, Truhlik, V., Richards, P., Olsen, Nils, and Lühr, H.

Abstract

In recent years a growing number of satellite measurements in the ionosphere and thermosphere provide long and continuous data records which enable the investigation of climatological trends and the quantification of regular variations or isolated events. The CHAMP mission provides a valuable base of in situ measurements of the ionosphere and thermosphere between 300 and 400 km altitude and for years from 2000 to 2010. In our presentation we will discuss an example of the analysis of observed electron temperature (Te) and density together with physics based model results investigating the equatorial Te morning overshoot (MO). Both, data and model revealed an anti-correlation between the equatorial MO amplitude and solar EUV flux at these altitudes. The CHAMP observations also reveal a post sunset electron temperature anomaly in analogy to the equatorial ionisation anomaly at altitudes below 400 km, although this was not predicted by earlier models. The temperature peaks coincides with the density peaks and are increased during high solar flux. Even more extended possibilities in investigating the ionosphere/thermosphere system are expected from the ESA Swarm satellite constellation mission. Provided products relevant for investigating the near Earth Space will be presented.

Published
2012

231. Status of CHAMP Mission

Author

Reigber, C., Lühr, H., Schwintzer, P., 1.2 Global Geomonitoring and Gravity Field, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, 1.1 GPS/GALILEO Earth Observation, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Gravity Field and Gravimetry -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
550 - Earth sciences
Published
2000

237. CHAMP Science Data Ground System and Expected Mission Products

Author

Reigber, C., Förste, C., Lühr, H., Schwintzer, P., 1.2 Global Geomonitoring and Gravity Field, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, 1.1 GPS/GALILEO Earth Observation, 1.0 Geodesy and Remote Sensing, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum, and Gravity Field and Gravimetry -2009, Geoengineering Centres, GFZ Publication Database, Deutsches GeoForschungsZentrum

Subjects
550 - Earth sciences
Published
1999

238. Thermospheric mass density variations during geomagnetic storms and a prediction model based on the merging electric field

Author

Liu, R. (author), Lühr, H. (author), Doornbos, E. (author), Ma, S.Y. (author), Liu, R. (author), Lühr, H. (author), Doornbos, E. (author), and Ma, S.Y. (author)

Abstract

With the help of four years (2002–2005) of CHAMP accelerometer data we have investigated the dependence of low and mid latitude thermospheric density on the merging electric field, Em, during major magnetic storms. Altogether 30 intensive storm events (Dstmin

Published
2010
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239. International Geomagnetic Reference Field: the eleventh generation

Author

Finlay, C.C., Maus, S., Beggan, C.D., Bondar, T.N., Chambodut, A., Chernova, T.A., Chuillat, A., Golovkov, V.P., Hamilton, B., Hamoudi, M., Holme, R., Hulot, G., Kuang, W., Langlais, B., Lesur, V., Lowes, F.J., Lühr, H., Macmillan, S., Mandea, M., McLean, S., Manoj, C., Menvielle, M., Michaelis, I., Olsen, N., Rauberg, J., Rother, M., Sabaka, T.J., Tangborn, A., Tøffner-Clausen, L., Thébault, E., Thomson, A.W.P., Wardinksi, I., Wei, Z., Zvereva, T.I., Finlay, C.C., Maus, S., Beggan, C.D., Bondar, T.N., Chambodut, A., Chernova, T.A., Chuillat, A., Golovkov, V.P., Hamilton, B., Hamoudi, M., Holme, R., Hulot, G., Kuang, W., Langlais, B., Lesur, V., Lowes, F.J., Lühr, H., Macmillan, S., Mandea, M., McLean, S., Manoj, C., Menvielle, M., Michaelis, I., Olsen, N., Rauberg, J., Rother, M., Sabaka, T.J., Tangborn, A., Tøffner-Clausen, L., Thébault, E., Thomson, A.W.P., Wardinksi, I., Wei, Z., and Zvereva, T.I.

Abstract

The eleventh generation of the International Geomagnetic Reference Field (IGRF)was adopted in December 2009 by the International Association of Geomagnetism and Aeronomy Working Group V-MOD. It updates the previous IGRF generation with a definitive main field model for epoch 2005.0, a main field model for epoch 2010.0, and a linear predictive secular variation model for 2010.0–2015.0. In this note the equations defining the IGRF model are provided along with the spherical harmonic coefficients for the eleventh generation. Maps of the magnetic declination, inclination and total intensity for epoch 2010.0 and their predicted rates of change for 2010.0–2015.0 are presented. The recent evolution of the South Atlantic Anomaly and magnetic pole positions are also examined.

Published
2010

240. Geomagnetic research from Space

Author

Friis-Christensen, Eigil, Lühr, H., Hulot, G., Haagmans, R., Purucker, M., Friis-Christensen, Eigil, Lühr, H., Hulot, G., Haagmans, R., and Purucker, M.

Published
2009

242. Equatorial electrojet as part of the global circuit : a case-study from the IEEY

Author

Kobea, A.T., Amory-Mazaudier, C., Do, J.M., Lühr, H., Houngninou, E., Vassal, Jacques, Blanc, E., and Curto, J.J.

Subjects
CHAMP MAGNETIQUE, ELECTROMAGNETISME, VARIATION TEMPORELLE, IONOSPHERE, Physics::Space Physics, VARIATION SPATIALE, GEOPHYSIQUE, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics
Abstract

Geomagnetic storm-time variations often occur coherently at high latitude and the day-side dip equator where they affect the east ward Sq field. This paper presents an analysis of ground magnetic field and ionospheric electrodynamic data related to the geomagnetic storm which occurred on the 27 may 1993 during the international Equatorial Electrojet Year during (IEEY) experiment. This storm-signature analysis on the auttoral, mid-latitude and equatorial ground field, and the ionospheric electrodynamic data leads to the identification of a sensitive response of the equatorial electrojet (EEJ) to large scale-auttoral return current : this response consists in a change of the eastward electric field during the pre-sunrise hours (0400-0600 UT) coherently to the high-, mid-, and equatorial-latitude H decrease and the decrease and the disappearance of the EEJ irregularities between the time-interval 0800-0950 UT. Subsequent to the change in h'F during pre-sunrise hours, the observed foF2 increase revealed an enhancement of the equatorial ionization anomaly (EIA) caused by the high-latitude penetrating electric field. The strengthening of these irregaluraties attesting by the Doppler frequency increase track the H component at the equator which undergoes a rapid increase around 0800 UT. The DeltaH variations observed at the equator are the sum of the following components S (subR), DP, DR, DCF and DT. (Résumé d'auteur)

Published
1998

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