2024/11/25 by Fahad Khan Khadim, Augusto Getirana, Rajat Bindlish +4 · 1 voice
Earth and Planetary Sciences · #Oceanographic and Atmospheric Processes #Arctic and Antarctic ice dynamics #Geology and Paleoclimatology Research
paper · pdf · doi:10.1073/pnas.2412551121
openalex publication_date 2024/11/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Sea surface salinity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">SSS</mml:mi> </mml:mrow> </mml:math> ) is a key parameter in the thermohaline circulation of global oceans. Near the megadeltas, inland streamflow through large catchments plays a crucial role in mediating salinity. While some regional studies have investigated how <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">SSS</mml:mi> </mml:mrow> </mml:math> is impacted through water cycle and climate components, a global scale quantification of inland streamflow contribution on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">SSS</mml:mi> </mml:mrow> </mml:math> variability is lacking. Here, we utilized remote sensing and observation-driven datasets to quantify the statistical associations between <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">SSS</mml:mi> </mml:mrow> </mml:math> and streamflow ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msub> <mml:mi>Q</mml:mi> <mml:mrow> <mml:mi mathvariant="italic">basin</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) at 48 megadeltas worldwide. This study uncovers a robust negative association between <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msub> <mml:mi>Q</mml:mi> <mml:mrow> <mml:mi mathvariant="italic">basin</mml:mi> </mml:mrow> </mml:msub> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">SSS</mml:mi> </mml:mrow> </mml:math> , with correlation coefficients <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mfenced close=")" open="("> <mml:mi>R</mml:mi> </mml:mfenced> </mml:math> less than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>0.6</mml:mn> </mml:mrow> </mml:math> for seasonal data found in 26 of the 48 megadeltas, and less than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>0.4</mml:mn> </mml:mrow> </mml:math> for deseasoned data in 21 megadeltas. The anticorrelation relationship is more pronounced in large deltas, particularly near tropical climates and in river-influenced deltas. The study also underscores the significant roles of climate, morphological, and anthropogenic stratification in impacting the natural influence of freshwater discharge on SSS . By highlighting the interconnected impacts of alterations in terrestrial water cycle upstream and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mrow> <mml:mi mathvariant="italic">SSS</mml:mi> </mml:mrow> </mml:math> , this work contributes to enhancing our understanding of global ocean and climate circulation patterns and in tackling environmental issues pertaining to marine ecosystems.