????GPS??GRACE?????????????????????????????

????????GPS??GRACE??????????????????????????????????????е????????ICE-5G and ICE-3G???????????????????????????????????????????е??????????????????????????????????????????????????仯????????????GRACE?????????????????ICE-5G????????????????????????????????????????????С~20%??????????????????????~40%?????????????????????α???????仯??GPS??GRACE???????????????????????????????????????????????????????Ч??? (~150 km??80%?????) ?????????????????????????~90 km); ????μ?????Ч??????????3.7 × 10²⁰?? Pas ??1.9 × 10²¹?? Pas (90%?????)???????????????????????????С~20%??

GLACIAL ISOSTATIC ADJUSTMENT MODELS CONSTRAINED BY JOINT INVERSION OF GPS AND GRACE SATELLITE OBSERVATIONS IN NORTH AMERICA

We present a joint inversion analysis of the GPS??derived radial (vertical) deformation and GRACE??derived gravity rates in North America to examine whether the ice??sheet models (ICE??5G and ICE??3G) can fit the satellite based observations. The results show that the existing ice??sheet models can not correctly predict the concentration of gravity change observed by GRACE in two areas of west and southeast of Hudson Bay. Tests of modifying ICE??5G show that a reduction of ice thickness by about 20% in the west area of Hudson Bay and an increase by about 40% in the southeast are required to fit both observed vertical deformation and gravity changes by GPS and GRACE.The results of joint inversion demonstrate that the estimated effective lithosphere thickness (150 km, under a statistical confidence level of 80%) is apparently larger than that valuation (chouq 90 km) inferred from relative sea??level data, while the upper??and lower??mantle viscosity estimates (3.7 × 10²⁰?? Pa s; 1.9 × 10²¹?? Pas; 90% confidence level) are about 20% smaller than those derived from sea??level indicators.