Figure 4. Sampling error for ratios ranges from 0.01 to 0.5.
Example in the time domain: GRACE monthly solutions
Temporal variations of the gravity field globally are monitored by the GRACE (between 2002-2017) and the GRACE-FO (from 2018) missions (Bettadpur, 2007). Mass variation in the Amazonas basin is dominated by the annual period of the hydrological cycle (c.f. gravity anomaly time series from GRACE and GRACE-FO monthly solutions in Figure 5). The monthly sampling is equivalent to N=1/12=0.083. Using (14) and (29), the maximal L1-norm sampling error becomes 2.27%, while the maximal L2-norm error is 2.49%.