Lopez
Manuel
Lopez
Manuel
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PreprintHydrographic conditions near the coast of northwestern Baja California : 1997–2004( 2005-05-18) Perez-Brunius, Paula ; Lopez, Manuel ; Pineda, JesusThe effects of the 1997-98 and 2002-04 El Ni˜no on the upper waters in the con- tinental shelf and slope regions off northwestern Baja California are explored with data from eight cruises taken in late spring from 1998 to 2004 and the summers of 1997 and 1998. Geostrophic velocities were calculated referenced to a specific vol- ume anomaly surface separating the southward flowing California Current waters from the waters advected to the north by the California Undercurrent. The result- ing fields show equatorward flow near the surface except in the summer of 1997, when a poleward jet was found in the upper 40 dbars. This shallow jet advected anomalously warm and salty waters characteristic of the 1997-98 El Ni˜no, with its core found within 20-30 kms from the coast. By spring of 1998, the waters brought into the region by the jet had mixed across the pycnoline with the salty California Undercurrent waters below, resulting in high salinity levels on the density surfaces corresponding to the otherwise fresh California Current waters (25-26¾t). By con- trast, the 2002-04 El Ni˜no stands out for the very fresh and cold waters found on the same density surfaces in late spring of 2003 and 2004, marking a pronounced presence of subarctic waters. The fresh conditions found on the latter years repre- sent a nearshore expresion of the anomalous intrusion of subarctic waters observed 50-150 km from the coast of Southern California and Punta Eugenia, reported from July 2002 until April 2003. Our results suggest that the presence of this intrusion has continued to influence the region at least until May 2004.
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ArticleComparison of upwelling indices off Baja California derived from three different wind data sources(California Cooperative Oceanic Fisheries Investigations, 2007-12) Perez-Brunius, Paula ; Lopez, Manuel ; Pares-Sierra, Alejandro ; Pineda, JesusWe compared the NOAA Southwest Fisheries Science Center’s Environmental Research Division (formerly Pacific Fisheries Environmental Laboratory: PFEL) coastal upwelling indices along the northern Baja California coast with those derived from winds measured by coastal meteorological stations and estimated by the QuikSCAT satellite. With the exception of the PFEL series at 33°N, the three data sets compare reasonably well, having similar typical year patterns, correlations >0.6, and significant coherences for periods three to five days or longer. By contrast, the seasonal variations, the timing and magnitude of maximum upwelling, and the variability of the PFEL indices at 33°N are significantly different compared to all the other time series, including QuikSCAT at that location. The performance of the QuikSCAT winds close to shore was evaluated using the coastal meteorological station data. Although large root-meansquare (RMS) errors in direction were found for the QuikSCAT winds, both datasets have properties similar to the variance ellipses, and show reasonable coherences for frequencies in the weather band and lower, particularly south of 33°N.
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ArticleSpatially heterogeneous, synchronous settlement of Chthamalus spp. larvae in northern Baja California(Inter-Research, 2005-11-04) Ladah, Lydia B. ; Tapia, Fabian J. ; Pineda, Jesus ; Lopez, ManuelWe evaluated the spatial variability in barnacle settlement at scales of 10s to 100s of meters (among-sites: 300 m; within-site: 30 m) along 1 km of coastline in the Bay of Todos Santos, northern Baja California, Mexico. Settlement of the intertidal barnacles Chthamalus spp. was monitored daily from April 1 to May 10, 2002, and thereafter every other day to September 18, 2002. Concurrently, temperature of the water column was measured every 15 min, and hourly wind speed and direction data were acquired from a nearby site. We identified 12 settlement pulses during our study, with all but 2 pulses showing significant differences in mean settlement at either or both spatial scales. Despite a high variability in numbers, settlement pulses were synchronous between sites. The occurrence of settlement pulses was significantly correlated with a rapid increase in the stratification of nearshore waters, but not correlated with sudden fluctuations in the direction of winds perpendicular to the shore. Sudden changes in the stratification of nearshore waters have been associated with the occurrence of internal tidal bores. Our results suggest that internal motions, more specifically internal tidal bores, could be an important mechanism for the onshore transport of larvae in the Bay of Todos Santos.