Figure S2. WRMS reduction ratio for GPS stations in the Amazon Basin; circles denote
the results for the north component, and diamonds are for the east component, and
triangles are for the vertical component. This figure indicates that the correlations of
horizontal seasonal variations between GPS and GRACE depend on their relative
locations to the load. For the GPS stations located west and east of the load, such as
QUI1, QUI2, RIOP, RECF, BRAZ, and SAVO, the correlation is good in the east
direction (diamond) and poor in the north direction (circle). This is because their
horizontal seasonal movements are mainly in the east-west direction. For the stations on
the south side of the load, such as UFPR, CHPI and UEPF, the correlations in the north
component (circle) are much better than those in the east component (diamond). Triangle
denotes WRMS reduction in height.
WRMS (Weighted Root-Mean-Squares) reduction ratio was defined by [Fu et al., 2012]
to assess the correlations between GPS measured and GRACE modeled seasonal
deformation.
𝑊𝑅𝑀𝑆𝐺𝑃𝑆 − 𝑊𝑅𝑀𝑆𝐺𝑃𝑆−𝐺𝑅𝐴𝐶𝐸
𝑅𝑎𝑡𝑖𝑜𝑊𝑅𝑀𝑆_𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 =
𝑊𝑅𝑀𝑆𝐺𝑃𝑆 − 𝑊𝑅𝑀𝑆𝐺𝑃𝑆−𝐺𝑃𝑆𝑓𝑖𝑡
where 𝑊𝑅𝑀𝑆𝐺𝑃𝑆 is the WRMS of the GPS seasonal (detrended) timeseries;
𝑊𝑅𝑀𝑆𝐺𝑃𝑆−𝐺𝑅𝐴𝐶𝐸 is the WRMS of the GPS timeseries with seasonal effects corrected by
GRACE-modeled seasonal displacements; 𝑊𝑅𝑀𝑆𝐺𝑃𝑆−𝐺𝑃𝑆𝑓𝑖𝑡 is the WRMS of the GPS
timeseries with seasonal components removed by fitting seasonal terms to the GPS
timeseries. A value of +1.0 would represent perfect agreement between GPS-observed
and GRACE-modeled seasonal deformation. So higher WRMS reduction ratio represents
better correlation between GPS and GRACE.
Reference:
Fu, Y., J. T. Freymueller, and T. Jensen (2012), Seasonal hydrological loading in
southern Alaska observed by GPS and GRACE, Geophys. Res. Lett., 39, L15310,
doi:10.1029/2012GL052453.