Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2022, Vol. 19, No. 2, pp. 183-192
Comparative analysis of Okhotsk Sea surface temperature from satellite observations and ERA5 reanalysis
D.M. Lozhkin
1 , G.V. Shevchenko
1, 2 1 Russian Federal Research Institute of Fisheries and Oceanography, Sakhalin Branch, Yuzhno-Sakhalinsk, Russia
2 Institute of Marine Geology and Geophysics FEB RAS, Yuzhno-Sakhalinsk, Russia
Accepted: 15.03.2022
DOI: 10.21046/2070-7401-2022-19-2-183-192
For the Sea of Okhotsk and adjacent waters (the area bounded by coordinates 42–60 N and 135–160 E), a comparison of the monthly average Sea Surface Temperature (SST) series based on satellite data (SakhNIRO base) and the ERA5 reanalysis for 1998–2020 was performed. It is shown that in the study area, the winter and summer reanalysis SST is higher than the satellite SST. On the contrary, in autumn and especially in spring in most of the water area, the satellite SST is higher than the reanalysis SST. Differences in annual averages are small, except for some dynamically active regions. The first mode of the SST difference field’s expansion in terms of the analysis of natural orthogonal functions describes only 27 % of the total dispersion of investigated parameter. Its spatial distribution in almost the entire area has negative values. No stable seasonal variations were found in its temporal function, the main role is played by positive (to a lesser extent negative) emissions, indicating significant discrepancies in certain months, mainly summer. The moderate share of the first mode in the total variance of the parameter and the absence of stable cyclical components in the temporal function suggests that the differences in the spatiotemporal variability of SST from different data sources are not regular, but are caused by random factors. An exception is the presence of a pronounced cycle with a period of 11 years that may be associated with the inclusion of solar activity in the reanalysis model.
Keywords: sea surface temperature, satellite observations, reanalysis, empirical orthogonal functions
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