Satellite-Observed Time and Length Scales of Global Sea Surface Salinity Variability: A Comparison of Three Satellite Missions
Abstract
:1. Introduction
2. Materials and Methods
2.1. Data
2.1.1. Satellite Sea Surface Salinity
2.1.2. Other Data
2.2. Methods
2.2.1. Estimation of the Time Scales
2.2.2. Estimation of the Length Scales
3. Results
3.1. Temporal Scales of SSS Variability
3.1.1. Agreement on the Global Pattern
3.1.2. Regional Differences and Possible Reasons
3.2. Spatial Scales of SSS Variability
3.2.1. Agreement on the Global Pattern
3.2.2. Regional Differences and Possible Reasons
4. Discussion
5. Conclusions
- The geographic patterns of the time and length scales of SSS variability are generally consistent between the three satellite missions, although there are noticeable quantitative differences. The differences are likely due to differences in the design and sampling strategy between the satellite missions and/or different level of noise in the data.
- The temporal scales of SSS variability vary from more than 90 days. The longest time scales (up to 160 days) are observed in the western tropical Pacific and are related to the ENSO variability. The very short time scales (close to the Nyquist period) in some parts of the ocean are likely due to high levels of noise in the data (high noise-to signal ratio).
- The longest-length scales are in the tropics (with slight asymmetry around the Equator such as the longest scales are observed in the North Hemisphere around 5°N–10°N) and decrease towards higher latitudes.
- The length scales are anisotropic in the tropics (the zonal scales are generally shorter than the meridional ones) and become isotropic towards higher latitudes.
- The processes governing the SSS distribution and variability are non-stationary. The complex spatial patterns of the time and length scales of SSS variability seem to reflect the underlying physical process governing the variability.
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
Appendix A. Error Variance of Satellite SSS Dataset
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Yi, D.L.; Melnichenko, O.; Hacker, P.; Fan, K. Satellite-Observed Time and Length Scales of Global Sea Surface Salinity Variability: A Comparison of Three Satellite Missions. Remote Sens. 2022, 14, 5435. https://doi.org/10.3390/rs14215435
Yi DL, Melnichenko O, Hacker P, Fan K. Satellite-Observed Time and Length Scales of Global Sea Surface Salinity Variability: A Comparison of Three Satellite Missions. Remote Sensing. 2022; 14(21):5435. https://doi.org/10.3390/rs14215435
Chicago/Turabian StyleYi, Daling Li, Oleg Melnichenko, Peter Hacker, and Ke Fan. 2022. "Satellite-Observed Time and Length Scales of Global Sea Surface Salinity Variability: A Comparison of Three Satellite Missions" Remote Sensing 14, no. 21: 5435. https://doi.org/10.3390/rs14215435