Wind speed trends over the southwestern Atlantic Ocean, between 33° and 50°S

Abstract

Surface scalar wind speed trends (from 1979 to 2009) at the southwestern Atlantic Ocean, between 33° and 50°S and 55° and 70°W, were estimated from the NCEP/NCAR I (NR1) and the Climate Forecast System Reanalysis (CFSR) using Sen's slope. Trends were tested using the seasonal Mann–Kendall test. Scalar wind speed trends computed from NR1 database were positive throughout the whole study area, with values ranging from +0.01 to +0.03 m s−1 year−1. On the contrary, wind speed trends computed from CFSR database were rather different to trends obtained from NR1 reanalysis. Wind speed and sea surface temperature (SST) trend patterns, both computed from CFSR database, seem to be quite consistent but, in general, no apparent relationship between both patterns was obtained when different global databases were analysed. Sea surface wind speed data compiled from multiple satellite observations were also used to compute wind speed trends. Computed satellite trends resulted in very good agreement with positive values obtained from NR1 database. NR1 data series presented significant inter‐annual to multi‐decadal oscillations at the Argentinean continental shelf, but they would not seem to be associated either with the Southern Annular Mode or with El Niño Southern Oscillation. Possible impacts of positive speed wind trends on the mean depth of the ocean mixed layer and on the wind wave climate are briefly discussed.

Uncertainty in recent near-surface wind speed trends: a global reanalysis intercomparison

“…Positive values correspond to increasing trends whereas negative values denote slowing wind speeds. This linear regression method has been used instead of a more complex technique such as the Theil-Sen Slope estimator (Theil 1950, Sen 1968) since it has been demonstrated that they produce very similar results (Pescio et al 2016).…”

“…The observations used in the reanalyses are not the only source of uncertainty affecting these products, also there are some errors in the assimilation systems that can have an impact on the quality of the reanalyses (Reichler and Kim 2008). To address the uncertainty inherent in the estimation of longterm trends (Liléo et al 2013, Nchaba et al 2017, Pescio et al 2016 the use of more than one reanalysis has been recommended. A multi-reanalysis approach allows the quantification of the individual reanalysis uncertainty and the identification of robust signals that could be distinguished from artifacts in the observational data sources.…”

Wind Pattern Change Along a Period of Coastal Occurrence Variation of a Stinging Medusa on a SW Atlantic Beach

“…Different changes in atmospheric processes have been previously reported for the southwestern Atlantic Ocean (Gregg & Conkright, 2002;Severov et al, 2004;Simionato et al, 2005;Dragani et al, 2013;Pescio et al, 2015), and in particular for the Argentine platform (Martos & Piccolo, 1988;Lucas et al, 2005;Auad & Martos, 2012;Delgado et al, 2012). The passage of cyclones produced from baroclinic and lee topographic instability of the westerlies seemed to cause the high temporal variability of the winds over the southeastern South Atlantic (Gan & Rao, 1991).…”

An estimation of the effect of a possible wind speed increase on the ocean mixed layer depth at the northern Patagonian continental shelf

“…The raw analysis of the NR1 data shows no temporal trend in variables, except in the wind (Pescio et al, 2015) where we find an increment of 1.7 ± 0.9 cm s −1 /yr at a 95% confidence level. The analogous result for the B node is 2.2 ± 0.9 cm s −1 /yr.…”