[1] Univ Maryland Baltimore Cty, Joint Ctr Earth Syst Technol, 1000 Hilltop Circle,TRC 182, Baltimore, MD 21250 USA
[2] E GEOS SpA, I-75100 Contrada Terlecchie, Matera, Italy
[3] Hitotsubashi Univ, Kunitachi, Tokyo, Japan
[4] Tech Univ Munich, Geodat Observ Wettzell, D-93444 Bad Kotzting, Germany