An assessment of variance in ocean current signal and noise shared by in situ observations (drifters) and a large gridded analysis (GlobCurrent) is sought as a function of day of the year for 1993-2015 and across a broad spectrum of current speed. Regardless of the division of collocations, it is difficult to claim that any synoptic assessment can be based on independent observations. Instead, a measurement model that departs from ordinary linear regression by accommodating error correlation is proposed. The interpretation of independence is explored by applying Fuller's (1987) concept of equation and measurement error to a division of error into shared (correlated) and unshared (uncorrelated) components, respectively. The resulting division of variance in the new model favours noise. Ocean current shared (equation) error is of comparable magnitude to unshared (measurement) error and the latter is, for GlobCurrent and drifters respectively, comparable to ordinary and reverse linear regression. Although signal variance appears to be small, its utility as a measure of agreement between two variates is highlighted. Sparse collocations that sample a dense grid permit a first order autoregressive form of measurement model to be considered, including parameterizations of analysis-in situ error cross-correlation and analysis temporal error autocorrelation. The former (cross-correlation) is an equation error term that accommodates error shared by both GlobCurrent and drifters. The latter (autocorrelation) facilitates an identification and retrieval of all model parameters. Solutions are sought using a prescribed calibration between GlobCurrent and drifters (by variance matching). Because the true current variance of GlobCurrent and drifters is small, signal to noise ratio is near zero at best. This is particularly evident for moderate current speed and meridional current component.
翻译:对洋流信号差异和洋流信号差异和由现场观测(离心器)和大网格分析(GlobCurentrent)所共享的噪音差异进行评估是作为1993-2015年全年的一天函数,并贯穿当前速度的广泛范围。不管合用同一地点的不同,很难说任何综合评估都可以以独立观测为基础。相反,提出了一种测量模型,这种模型与普通线性回归不同,可以容纳错误相关关系,从而与普通线性回归相背离。探索了独立性的诠释方法,将Fuller的1987年方程和度度值校正值差概念分别应用于将误差分为共享(coral相关)和未共享(clobCoralCral)的值差因新模型而产生差异。对于当前正向电网的精确度差异,采用当前正值正值和后期的比值分析(Clobrentral-ralorral)的度误差与前位误差等。对于GlobCral-ral-loral-deal-deal-deal-deal disal disal dismal dismlation的测法是典型的明显和前制式的明显分析。