The Combined Gravity Model GGM05C

GGM05C is an unconstrained global gravity model complete to degree and order 360 determined from 1) GRACE K-band intersatellite range-rate data, GPS tracking and GRACE accelerometer data, 2) GOCE gradiometer data (ZZ+YY+XX+XZ) spanning the entire mission using a band pass filter of 10-50 mHz and polar gap filled with synthetic gradients from GGM05S to degree/order 150 evaluated at 200-km altitude, and 3) terrestrial gravity anomalies from DTU13 (Andersen et al., 2014). The value for C20 has been replaced with a value derived from satellite laser ranging. No rate terms were modeled.
For additional details on the background modeling, see the CSR RL05 processing standards document available at ftp://podaac.jpl.nasa.gov/allData/grace/docs/L2-CSR0005_ProcStd_v4.0.pdf (Bettadpur 2012). Detailed information about GGM05C is available at ftp://ftp.csr.utexas.edu/pub/grace/GGM05/README_GGM05C.pdf (Ries et al., 2016).

GGM05C是一个完整至360阶次（degree and order）的无约束全球重力模型（unconstrained global gravity model），其构建基于三类数据：1）GRACE K波段星间距离速率数据、GPS跟踪数据及GRACE加速度计数据；2）GOCE梯度仪数据（ZZ+YY+XX+XZ），覆盖整个任务周期，采用10-50 mHz的带通滤波器（band pass filter）处理，极地间隙（polar gap）通过GGM05S模型至150阶次的合成梯度（synthetic gradient）填充（评估高度为200公里）；3）DTU13数据集提供的地面重力异常（terrestrial gravity anomaly）（Andersen等，2014）。C20项的值已替换为由卫星激光测距（satellite laser ranging）获取的值。未对任何速率项（rate term）进行建模。

关于背景建模的更多细节，请参见CSR RL05处理标准文档，该文档可通过以下链接获取：ftp://podaac.jpl.nasa.gov/allData/grace/docs/L2-CSR0005_ProcStd_v4.0.pdf（Bettadpur 2012）。有关GGM05C的详细信息，请访问：ftp://ftp.csr.utexas.edu/pub/grace/GGM05/README_GGM05C.pdf（Ries等，2016）。