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  • Northerly wind trends along the Portuguese marine coast since 1950
    Publication . Leitão, Francisco; Relvas, Paulo; Canovas, Fernando; Baptista, Vânia; Teodosio, M. A.
    Wind is a marine coastal factor that is little understood but has a strong interaction with biological productivity. In this study, northerly wind trends in three regions of the Portuguese coast (Northwestern: NW, Southwestern: SW, and Southern: S) were analyzed. Two datasets with long-term (ICOADS: 1960-2010) and short-term data (Satellite: 1989-2010) were used to complement one another. The study revealed the northerly wind yearly data to be non-stationary and highly variable between years. Overall, the northerly wind intensity increased throughout the 1960s regardless of the area and dataset. Between 1960 and 2010, the northerly wind increased at a linear rate of 0.24, 0.09, and 0.15ms-1 per decade in the NW, SW, and S coastal regions, respectively. The rate was higher in recent decades (1988-2009), with the wind intensity increasing by 0.4, 0.3, and 0.3ms-1 per decade in the NW, SW, and S regions, respectively. Analyses of the sudden shifts showed significant increases in northerly wind intensities after 2003, 2004, and 1998 in the NW, SW, and S coast, respectively. Exceptions were found for autumn (September for short-term data), when a decrease in northerly winds was observed in recent decades, regardless of the area, and for summer, when no changes in wind trends were recorded in the NW and SW. The long-term data also showed a major increase in northerly winds in winter (January and February), which is the recruitment season for many small and medium-sized pelagic fish. The increase in the intensity of the northerly winds over the past two decades and the past half-century occurred at a higher rate than was estimated by the IPCC for the next century.
  • Correction to: Northerly wind trends along the Portuguese marine coast since 1950
    Publication . Leitão, Francisco; Relvas, Paulo; Canovas, Fernando; Baptista, Vânia; Teodósio, M. A.
    All figure captions are not accurate. Also, there is a repeated error in most figures because the vertical scales incorrectly show Wind Strenght instead of Wind Strength and in Fig. 4 (mid-panel) 2003 instead of 2004.
  • A 60-year time series analyses of the upwelling along the Portuguese Coast
    Publication . Leitão, Francisco; Baptista, Vânia; Vieira, Vasco; Laginha Silva, Patrícia; Relvas, Paulo; Teodosio, M A
    Coastal upwelling has a significant local impact on marine coastal environment and on marine biology, namely fisheries. This study aims to evaluate climate and environmental changes in upwelling trends between 1950 and 2010. Annual, seasonal and monthly upwelling trends were studied in three different oceanographic areas of the Portuguese coast (northwestern-NW, southwestern-SW, and south-S). Two sea surface temperature datasets, remote sensing (RS: 1985-2009) and International Comprehensive Ocean-Atmosphere Data Set (ICOADS: 1950-2010), were used to estimate an upwelling index (UPWI) based on the difference between offshore and coastal sea surface temperature. Time series analyses reveal similar yearly and monthly trends between datasets A decrease of the UPWI was observed, extending longer than 20 years in the NW (1956-1979) and SW (1956-1994), and 30 years in the S (1956-1994). Analyses of sudden shifts reveal long term weakening and intensification periods of up to 30 years. This means that in the past 60 years a normal climate UPWI occurred along the Portuguese coast. An intensification of UPWI was recorded in recent decades regardless of the areas (RS: 1985-2009). Such an intensification rate (linear increase in UPWI) is only significant in S in recent decades (increase rate: ICOADS = 0.02 degrees C decade-1; RS = 0.11 degrees C decade-1) while in NW and SW the increase rate is meaningless. In NW more stable UPWI conditions were recorded, however average UPWI values increased in autumn and winter in NW in recently decades (RS: 1985-2009). An intensification rate of UPWI was recorded during summer (July, August and September) in SW and S in latter decades (RS: 1985-2009). The average UPWI values increased in recent decades in autumn in S. Marked phenological changes were observed in S in summer (before downwelling conditions prevail whilst recently when UPWI regimes prevail) with UPWI seasonal regime in S in recent decades becoming similar to those found in SW and NW. Results of this work can contribute to a better understanding of how upwelling dynamics affect/are correlated with biological data.