Multiscale Analysis of the Relations Between Atmospheric and Oceanic Time Series Recorded by Fixed Moorings

Many marine buoys around the world record multiple parameters at high frequency and fixed position. Here we consider simultaneous oceanic and atmospheric temperature time series recorded by several buoys in the English Channel (L4 and E1 stations from Western Channel Observatory of the Plymouth Marine Laboratory and Marel Carnot station from Ifremer). The sampling times are between 20 minutes and one hour depending on the series. We consider the scaling properties of both series, and their cross-correlations. We show that at low frequencies both spectra are similar, while at higher frequencies, larger than about 10 days, they have different spectra. The atmospheric temperature variability is much larger at high frequencies. Exploiting the asymmetry of their cross-correlation, we show that atmospheric temperature leads marine temperature by a scale of 10-12 days, which is the latency time needed for atmospheric temperature variations to have influence on marine temperatures. With these approaches we can statistically characterize part of the coupling between both series, and also propose a causal model expressing the marine temperature time series from the atmospheric time series.