Impacts of Convergence on Structure Functions from Surface Drifters in the Gulf of MexicoSource: Journal of Physical Oceanography:;2019:;volume 049:;issue 003::page 675Author:Pearson, Jenna
,
Fox-Kemper, Baylor
,
Barkan, Roy
,
Choi, Jun
,
Bracco, Annalisa
,
McWilliams, James C.
DOI: 10.1175/JPO-D-18-0029.1Publisher: American Meteorological Society
Abstract: There are limitations in approximating Eulerian statistics from surface drifters, due to biases from surface convergences. By contrasting second- and third-order Eulerian and surface drifter structure functions obtained from a model of the Gulf of Mexico, the consequences of the semi-Lagrangian nature of observations during the summer Grand Lagrangian Deployment (GLAD) and winter Lagrangian Submesoscale Experiment (LASER) are estimated. By varying launch pattern and location, the robustness and sensitivity of these statistics are evaluated. Over scales less than 10 km, second-order structure functions of surface drifters consistently have shallower slopes (~r2/3) than Eulerian statistics (~r), suggesting that surface drifter structure functions differ systematically and do not reproduce the scalings of the Eulerian fields. Medians of Eulerian and cluster release second-order statistics are also significantly different across all scales. Synthetic cluster release statistics depend on launch location and weakly on launch pattern. The observations suggest little seasonal difference in the second-order statistics, but the LASER third-order structure function shows a sign change around 1 km, while GLAD and the synthetic cluster releases show a third-order structure function sign change around 10 km. Further, synthetic surface drifter cluster releases (and therefore likely the GLAD observations) show robust biases in the negative third-order structure functions, which may lead to significant overestimation of the spectral energy flux and underestimation of the transition scale to a forward energy cascade. The Helmholtz decomposition, and curl and divergence statistics, of Eulerian and cluster releases differ, particularly on scales less than 10 km, in agreement with observations of drifters preferentially sampling convergences in coherent structures.
|
Collections
Show full item record
contributor author | Pearson, Jenna | |
contributor author | Fox-Kemper, Baylor | |
contributor author | Barkan, Roy | |
contributor author | Choi, Jun | |
contributor author | Bracco, Annalisa | |
contributor author | McWilliams, James C. | |
date accessioned | 2019-09-22T09:03:14Z | |
date available | 2019-09-22T09:03:14Z | |
date copyright | 1/9/2019 12:00:00 AM | |
date issued | 2019 | |
identifier other | JPO-D-18-0029.1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl1/handle/yetl/4262546 | |
description abstract | There are limitations in approximating Eulerian statistics from surface drifters, due to biases from surface convergences. By contrasting second- and third-order Eulerian and surface drifter structure functions obtained from a model of the Gulf of Mexico, the consequences of the semi-Lagrangian nature of observations during the summer Grand Lagrangian Deployment (GLAD) and winter Lagrangian Submesoscale Experiment (LASER) are estimated. By varying launch pattern and location, the robustness and sensitivity of these statistics are evaluated. Over scales less than 10 km, second-order structure functions of surface drifters consistently have shallower slopes (~r2/3) than Eulerian statistics (~r), suggesting that surface drifter structure functions differ systematically and do not reproduce the scalings of the Eulerian fields. Medians of Eulerian and cluster release second-order statistics are also significantly different across all scales. Synthetic cluster release statistics depend on launch location and weakly on launch pattern. The observations suggest little seasonal difference in the second-order statistics, but the LASER third-order structure function shows a sign change around 1 km, while GLAD and the synthetic cluster releases show a third-order structure function sign change around 10 km. Further, synthetic surface drifter cluster releases (and therefore likely the GLAD observations) show robust biases in the negative third-order structure functions, which may lead to significant overestimation of the spectral energy flux and underestimation of the transition scale to a forward energy cascade. The Helmholtz decomposition, and curl and divergence statistics, of Eulerian and cluster releases differ, particularly on scales less than 10 km, in agreement with observations of drifters preferentially sampling convergences in coherent structures. | |
publisher | American Meteorological Society | |
title | Impacts of Convergence on Structure Functions from Surface Drifters in the Gulf of Mexico | |
type | Journal Paper | |
journal volume | 49 | |
journal issue | 3 | |
journal title | Journal of Physical Oceanography | |
identifier doi | 10.1175/JPO-D-18-0029.1 | |
journal fristpage | 675 | |
journal lastpage | 690 | |
tree | Journal of Physical Oceanography:;2019:;volume 049:;issue 003 | |
contenttype | Fulltext |