SMAP and CalCOFI Observe Freshening during the 2014–2016 Northeast Pacific Warm Anomaly

Jorge Vazquez-Cuervo,Jose Gomez-Valdes

doi:10.3390/rs10111716

Jorge Vazquez-Cuervo, Jose Gomez-Valdes

Open Access

https://doi.org/10.3390/rs10111716

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Journal: Remote sensing	Publication Date: Oct 31, 2018
Citations: 5	License type: CC BY 4.0

Affiliation: California Institute of Technology

Abstract

Data from NASA’s Soil Moisture Active Passive Mission (SMAP) and from the California Cooperative Oceanic Fisheries Investigations (CalCOFI) were used to examine the freshening that occurred during 2015–2016 in the Southern California Current System. Overall, the freshening was found to be related to the 2014–2016 Northeast Pacific Warm Anomaly. The primary goal was to determine the feasibility of using SMAP data to observe the surface salinity signal associated with the warming and its coastal impact. As a first step, direct comparisons were done with salinity from the CalCOFI data at one-meter depth. During 2015, SMAP was saltier than CalCOFI by 0.5 Practical Salinity Units (PSU), but biases were reduced to <0.1 PSU during 2016. South of 33°N, and nearer to the coast where upwelling dominates, SMAP was fresher in 2015 by almost 0.2 PSU. CalCOFI showed freshening of 0.1 PSU. North of 33°N, SMAP and CalCOFI saw significant freshening in 2016, SMAP by 0.4 PSU and CalCOFI by 0.2 PSU. Differences between SMAP and CalCOFI are consistent with the increased stratification in 2015 and changes in the mixed layer depth. SMAP observed freshening that reached the Baja California Coast.

Highlights

A well-documented marine heat wave occurred in the Northeast Pacific during the period 2014–2016
For the Soil Moisture Active Passive Mission (SMAP) and California Cooperative Oceanic Fisheries Investigations (CalCOFI) co-locations, we used the criterion of 100 km from the coast to delineate open ocean and coastal comparisons
The SMAP Sea Surface Salinity (SSS) can be used to monitor the freshening in a coastal region associated with a major warming event

Summary

Introduction

A well-documented marine heat wave occurred in the Northeast Pacific during the period 2014–2016 (the 2014–2016 warm anomaly). Based on an analysis using NASA’s Multiscale Ultra-highResolution Sea Surface Temperature (MUR SST), [1] reported that SST anomalies along the West Coast of the United States were warmer than usual during the period 2014–2016, relative to the 2002–2012 climatology. They found that during the upwelling season, the anomalies were abated along the coast. The work in [5] analyzed the influence of the 2015–2016 El Niño years on the CCS They found that the effects of the equatorial Kelvin wave activity and the upwelling-favorable winds on the CCS were weaker than expected, especially for a strong El Niño. A study of the salinity variability from remote sensing during the 2014–2016 warm anomaly is lacking

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