TY - JOUR
T1 - Cross-spectral analysis of the SST/10-m wind speed coupling resolved by satellite products and climate model simulations
AU - Laurindo, Lucas C.
AU - Siqueira, Leo
AU - Mariano, Arthur J.
AU - Kirtman, Ben P.
PY - 2019/5/1
Y1 - 2019/5/1
N2 - This study aims to determine the spatial–temporal scales where the SST forcing of the near-surface winds takes places, and its relationship with the action of coherent ocean eddies. Here, cross-spectral statistics are used to examine the relationship between satellite-based SST and 10-m wind speed (w) fields at scales between 102–104 km and 101–103 days. It is shown that the transition from negative SST/w correlations at large-scales to positive at oceanic mesoscales occurs at wavelengths coinciding with the atmospheric first baroclinic Rossby radius of deformation; and that the dispersion of positively-correlated signals resembles tropical instability waves near the equator, and Rossby waves in the extratropics. Transfer functions are used to estimate the SST-driven w response in physical space (wc), a signal that explains 5–40% of the mesoscale w variance in the equatorial cold tongues, and 2–15% at extratropical SST fronts. The signature of ocean eddies is clearly visible in wc, accounting for 20–60% of its variability in eddy-rich regions. To provide further insight on the role of ocean eddies in the SST-driven coupling, the analysis is repeated for two climate model (CCSM) simulations using ocean grid resolutions of 1 ∘ (eddy-parameterized, LR) and 0. 1 ∘ (eddy-resolving, HR). The lack of resolved eddies in LR leads to a significantly underestimated mesoscale w variance relative to HR. Conversely, the wc variability in HR can exceed the satellite estimates by a factor of two at extratropical SST fronts and underestimate it by a factor of almost six near the equator, reflecting shortcomings of the CCSM to be addressed in its future developments.
AB - This study aims to determine the spatial–temporal scales where the SST forcing of the near-surface winds takes places, and its relationship with the action of coherent ocean eddies. Here, cross-spectral statistics are used to examine the relationship between satellite-based SST and 10-m wind speed (w) fields at scales between 102–104 km and 101–103 days. It is shown that the transition from negative SST/w correlations at large-scales to positive at oceanic mesoscales occurs at wavelengths coinciding with the atmospheric first baroclinic Rossby radius of deformation; and that the dispersion of positively-correlated signals resembles tropical instability waves near the equator, and Rossby waves in the extratropics. Transfer functions are used to estimate the SST-driven w response in physical space (wc), a signal that explains 5–40% of the mesoscale w variance in the equatorial cold tongues, and 2–15% at extratropical SST fronts. The signature of ocean eddies is clearly visible in wc, accounting for 20–60% of its variability in eddy-rich regions. To provide further insight on the role of ocean eddies in the SST-driven coupling, the analysis is repeated for two climate model (CCSM) simulations using ocean grid resolutions of 1 ∘ (eddy-parameterized, LR) and 0. 1 ∘ (eddy-resolving, HR). The lack of resolved eddies in LR leads to a significantly underestimated mesoscale w variance relative to HR. Conversely, the wc variability in HR can exceed the satellite estimates by a factor of two at extratropical SST fronts and underestimate it by a factor of almost six near the equator, reflecting shortcomings of the CCSM to be addressed in its future developments.
KW - Air–sea interaction
KW - Climate modeling
KW - Cross-spectral analysis
KW - Mesoscale ocean eddies
KW - Oceanic Rossby waves
KW - Satellite observations
UR - http://www.scopus.com/inward/record.url?scp=85053698283&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85053698283&partnerID=8YFLogxK
U2 - 10.1007/s00382-018-4434-6
DO - 10.1007/s00382-018-4434-6
M3 - Article
AN - SCOPUS:85053698283
VL - 52
SP - 5071
EP - 5098
JO - Climate Dynamics
JF - Climate Dynamics
SN - 0930-7575
IS - 9-10
ER -