RESuMEN Se realizaron tres cruceros (noviembre de 2002, y junio y noviembre de 2003) en la costa ... more RESuMEN Se realizaron tres cruceros (noviembre de 2002, y junio y noviembre de 2003) en la costa occidental de Baja California con el objetivo de analizar las variaciones espaciales y temporales del coeficiente de absorción específico de luz por el fitoplancton (a φ(λ)) y la concentración de pigmentos por cromatografía líquida de alta resolución (HPLC por sus siglas en inglés). Se encontró que en estaciones alejadas de la costa dominan aguas oligo-tróficas con clorofila a total (ClaT) superficial menor a 0.2 mg m -3 , mientras que cerca de la costa se observan aguas mesotróficas (ClaT superficial 0.2–2 mg m -3). En las estaciones oligotróficas dominan células del picoplancton mientras que en aguas costeras domina el microplancton. En noviembre de 2002 la proporción entre grupos fue similar, sin embargo, para junio de 2003 en la mayoría de las estaciones la abundancia del microplancton fue mayor a 50%. Para noviembre de 2003 se observó una tendencia similar a lo encontrado en 2002. E...
Algunas consideraciones tecnicas sobre la toma de muestra, almacenamiento tipo de fijador y metod... more Algunas consideraciones tecnicas sobre la toma de muestra, almacenamiento tipo de fijador y metodologia de conteo en muestras de agua para la evalución de la Taxocenosis fitoplanctonica en aguas costeras. Esta es una manual del Cuerpo Academico de Ecologia del Fitoplancton FCM-UABC en su serie White Papers
El propósito de este trabajo fue caracterizar el efecto de las surgcncias de "verano" en la distr... more El propósito de este trabajo fue caracterizar el efecto de las surgcncias de "verano" en la distribución espacial de conccntración"-de clorofila a (ehl .....) y T "C (TSS) de las aguas superficiales del Golfo de California. Para ello se generaron gráficas de TSS basadas en composiciones semanales de imágenes del sensor AVHRR del satélite NOAA-9, y de ehl"'l basadas en imágenes diarias del CZCS del satélite Nimbus-?, para la zona del Golfo de California al sur de las grandes islas. L1S surgcncias de verano del Golfo de California tienen un efecto apreciable en la distribución horizontal de TSS y Chl ... 1, pero es muy débil. Esto se debe principalmente a una estratificación muy fuerte de la columna de agua, con temperaturas superficiales de hasta >31 oC, que disminuye en gran medida el transporte vertical del agua cerca de la costa de Baja California. La TSS tiene una tendencia general de aumentar de la costa occidental del Golfo hacia la oriental, con un gradientc débil dc uno a dos grados a través de todo el Golfo (de 29 "C en la costa occidental a 31 "C en la oriental). Los valores dc Chl,al muestran un gradiente invcrso, con valores mayores cerca de la costa occidental del Golfo (hasta 0.2 mg m J) y disminuyendo a <0.1 mg m-l frente a la costa oriental. En algunos casos se mostraron lenguetas y remolinos claros, como los remolinos ciclónicos observados en la distribución de TSS con núcleus de 28 oc. Una Jcngucta de valores relativamente altos de Chl ..., (-0.2 mg m-J) indicó advección de Baja California hacia Sonora en la parte norte de nuestra zona de estudio.
Ocean color (OCTS, SeaWiFS) and sea surface temperature (AVHRR) images were used to evaluate spat... more Ocean color (OCTS, SeaWiFS) and sea surface temperature (AVHRR) images were used to evaluate spatial and temporal variability of the Brazil‐Malvinas Confluence and La Plata Plume (20° to 45°S and 40° to 65°W). The data set covers the period from January 1997 to June 2003. Chlorophyll and SST data were combined using Principal Component Analysis (PCA). The results yielded were used to identify and follow front displacements. PCA maps showed a close relationship with previous observations of currents behavior and the La Plata Plume. Firstly the analysis was performed on data retrieved from a monthly climatology, and the results show three remarkable features: a gradual increase of the northward intrusion of the La Plata Plume throughout the period lasting from summer to winter; the summer shape of the La Plata Plume showed a stronger penetration over the shelf on the Argentinean side of the estuary mouth; and the seasonal migration of the Brazil‐Malvinas Confluence. Monthly composites...
Surface mesoscale structures and wind variability in the northern Gulf of California (NGC) were a... more Surface mesoscale structures and wind variability in the northern Gulf of California (NGC) were analyzed using data from SeaWiFS (1 km) and QuikSCAT (1 day). The months of February and March were selected as representative of winter and the months of August and September were selected as representative of summer. Chlorophyll‐a (Chla) and wind time series were constructed using 16 points to analyze temporal variability and wind magnitude‐Chla temporal and spatial linear correlation. Wind components along and across the NGC were found to play an equally significant role regarding wind variability, contrary to what is currently recognized. Wind magnitude tended to be stronger in winter and had less wind direction variability than in summer. A bimodal wind pattern was registered for each season, each wind direction explaining less than 30% of total variability. The zone with minimum variability in wind direction and maximum variability in wind magnitude was located northwest of the NGC,...
Deep Sea Research Part II: Topical Studies in Oceanography, 2004
SeaWiFS high-resolution ocean-color images and AVHRR sea-surface temperature were obtained for th... more SeaWiFS high-resolution ocean-color images and AVHRR sea-surface temperature were obtained for the period from November 1998 to March 1999. Generation of mesoscale eddies was observed for the region between the Gulf of Tehuantepec and the Gulf of Papagayo (Tropical Pacific Ocean). Eighteen eddies with diameters ranging between 100 and 450 km were identified; 14 originated in the Gulf of Tehuantepec and most were cyclonic. Our results show that the frequency of cyclonic eddy formation is higher than it has been reported and their lifetime can be longer. Using both ocean color images and daily temporal resolution, instead of sea-surface temperature alone, improved our ability to identify and follow the propagation of these eddies. The generation and fate of smaller cyclonic eddies around the periphery of the anticyclonic eddy indicate the importance of the onshore-offshore exchange of energy and biological material, which has not been considered previously. Three anticyclonic eddies were generated in the Gulf of Papagayo. These eddies have a common origin, and they travel along the main flux of the Costa Rica Coastal Current (CRCC), which later turns offshore and joins the North Equatorial Current. This behavior can be seen clearly on SeaWiFS images and suggests that the CRCC influences eddy propagation. Time series of chlorophyll-a concentration and SST were obtained from two points at Tehuantepec and two at Papagayo. Cross-correlation analysis confirms an inverse relationship between these variables, showing that a decrease in SST is followed by an increase in chlorophyll-a concentration values, indicating high growth and primary production rates.
Deep Sea Research Part II: Topical Studies in Oceanography, 2004
From 15 to 19 October 1994, an oceanographic cruise was carried out in the Gulf of California. Ph... more From 15 to 19 October 1994, an oceanographic cruise was carried out in the Gulf of California. Phytoplankton biovolume, pigment concentrations, and taxonomy were examined as functions of location and light depth. The specific absorption coefficient of phytoplankton (a>h) showed variability in magnitude and spectral shapes between stations and with depth. The a*ph values ranged from 0.020-0.056 m2(mg chl a)-' at 440 nm to 0.013-0.020 m2(mg chl a)-' at 674 nm. Spectra of phytoplankton belonging to the same taxonomic group tended to have similar shape. At stations where the environmental conditions favored the presence of microphytoplankton populations (cells >20 pm), the lowest a* were found. Of all the variables studied, pigments, particularly the photoprotective pigment zeaxanthin, had the highest correlation with u*ph. Changes in pigment composition and cellular concentration were responsible for over 70% of the variability of the specific absorption at 440 nm. Including biovolume per cell in a multiple regression improved the model to explain up to 80% of a*ph variations. The work described here concurrently examined pigment packaging, measured as the cellular concentration of chlorophyll a and as the phytoplankton cell volume, and the confounding effect of the blue-absorbing accessory pigments on the specific absorption coefficient. The a;,, varied as a function of all three variables, indicating the importance of both taxonomic variations (size and accessory pigments) as well as responses to environmental variations.
ABSTRACT A dynamic regionalization of the Gulf of Mexico (GoM) was carried out based on normalize... more ABSTRACT A dynamic regionalization of the Gulf of Mexico (GoM) was carried out based on normalized radiances derived from MODIS-Aqua while considering its seasonal variability (Hurricane and Non-hurricane seasons). Daily images with a 1 km resolution from June 2002 to May 2007 were used. To define the dynamic regions, the first Standard Empirical Orthogonal Function (SEOF1) was calculated by combining nLw412 nm and nLw488 nm. The GoM was divided into two large provinces: oceanic and coastal. Within the oceanic province there are three regions with oligotrophic conditions. The coastal province displayed two sub-provinces (the northern and southern Gulf of Mexico) within which eight regions were located. Two of them were classified as transition regions. In general, most regions could be associated with general circulation patterns and/or river discharge influence. When looking at changes in coverage and the number of divisions, this regionalization shows a bi-seasonal modulation governed by hurricane seasons. The approximation presented here allows the dynamic regionalization of the GoM, a zone characterized by small surface gradients on Chl a and SST, including the recognition of smaller structures such as eddies.
This article was published in an Elsevier journal. The attached copy is furnished to the author f... more This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:
Tropical and subtropical Atlantic Ocean waters off the coasts of Brazil, Uruguay and Argentina ar... more Tropical and subtropical Atlantic Ocean waters off the coasts of Brazil, Uruguay and Argentina are influenced by a variety of hydrographic processes that lead to a great diversity in the biological system. In situ observations are scarce and sparsely distributed over this zone. Phytoplankton pigment concentrations were estimated utilizing the Coastal Zone Colour Scanner for the area located between 5 N and 45 S, and from the coast of South America eastward to 25 W. Advanced Very High Resolution Radiometer (sea surface temperature) and data from literature were used to differentiate regions, considering space and time variations of the phytoplankton biomass. Monthly pigment concentration time series were used for the period of January 1982-May 1986 as input for a Principal Component Analysis (PCA). The PCA analysis grouped 152 locations into 14 regions, most of them associated to clear surface circulation patterns and hydrographic features. These results were confirmed using monthly composites of chlorophylla concentration from Sea-viewing Wide Field-of-view Sensor for the period September 1997-April 2002. A connection between the 1982/83 and 1997/98 ENSO events and pigment distribution over southern and southeastern Brazil, as well as the Argentinean continental shelf, was clearly evidenced in temporal pigment distributions. Results presented in this work contribute to the idea that ocean colour images are an appropriate tool to identify and follow the seasonal displacement of biogeographical region boundaries.
Le contexte actuel de la confrontation armee en Colombie montre sur le terrain une diversite d... more Le contexte actuel de la confrontation armee en Colombie montre sur le terrain une diversite d'acteurs illegaux qu'actionnent de maniere indeterminee, tout en produisant des ruptures institutionnelles et sociales. Cette realite met en evidence la necessite pour l'Etat de mettre en œuvre les instruments permettant non seulement la reconstruction des tissus social et institutionnel, mais aussi pour mettre fin au conflit arme et assurer la reinsertion a la vie civile des acteurs armes. Cela est le constat d'une impossible " politique d'Etat " de reinsertion. Le politiques de paix transitoires sont a l'origine des ces consequences nefastes. La reinsertion des combattants se voit limitee a des instruments juridiques tels que l'amnistie et la grâce, sans tenir compte des causes qui etaient a l'origine de la confrontation. Ainsi, la gauche et la droite ont toujours hesite entre la solution negociee du conflit ou la confrontation armee. Entre tant les acteurs armes ont developpe leurs propres machines de guerre et ont deploye des strategies d'expansion tres efficace. Le budget general du programme national de reinsertion est tres maigre par rapport aux besoins socio-economiques des combattants, sans tenir compte des difficultes materielles pour leur execution. Le modele actuel de reinsertion reste encore a developper, a ameliorer. Dans cette recherche, nous voulions non seulement determiner les causes du conflit et la necessite de reinsertion des acteurs armes, mais aussi identifier les manques et les deficiences des programmes de reinsertion, pour nous approcher a une solution.
RESuMEN Se realizaron tres cruceros (noviembre de 2002, y junio y noviembre de 2003) en la costa ... more RESuMEN Se realizaron tres cruceros (noviembre de 2002, y junio y noviembre de 2003) en la costa occidental de Baja California con el objetivo de analizar las variaciones espaciales y temporales del coeficiente de absorción específico de luz por el fitoplancton (a φ(λ)) y la concentración de pigmentos por cromatografía líquida de alta resolución (HPLC por sus siglas en inglés). Se encontró que en estaciones alejadas de la costa dominan aguas oligo-tróficas con clorofila a total (ClaT) superficial menor a 0.2 mg m -3 , mientras que cerca de la costa se observan aguas mesotróficas (ClaT superficial 0.2–2 mg m -3). En las estaciones oligotróficas dominan células del picoplancton mientras que en aguas costeras domina el microplancton. En noviembre de 2002 la proporción entre grupos fue similar, sin embargo, para junio de 2003 en la mayoría de las estaciones la abundancia del microplancton fue mayor a 50%. Para noviembre de 2003 se observó una tendencia similar a lo encontrado en 2002. E...
Algunas consideraciones tecnicas sobre la toma de muestra, almacenamiento tipo de fijador y metod... more Algunas consideraciones tecnicas sobre la toma de muestra, almacenamiento tipo de fijador y metodologia de conteo en muestras de agua para la evalución de la Taxocenosis fitoplanctonica en aguas costeras. Esta es una manual del Cuerpo Academico de Ecologia del Fitoplancton FCM-UABC en su serie White Papers
El propósito de este trabajo fue caracterizar el efecto de las surgcncias de "verano" en la distr... more El propósito de este trabajo fue caracterizar el efecto de las surgcncias de "verano" en la distribución espacial de conccntración"-de clorofila a (ehl .....) y T "C (TSS) de las aguas superficiales del Golfo de California. Para ello se generaron gráficas de TSS basadas en composiciones semanales de imágenes del sensor AVHRR del satélite NOAA-9, y de ehl"'l basadas en imágenes diarias del CZCS del satélite Nimbus-?, para la zona del Golfo de California al sur de las grandes islas. L1S surgcncias de verano del Golfo de California tienen un efecto apreciable en la distribución horizontal de TSS y Chl ... 1, pero es muy débil. Esto se debe principalmente a una estratificación muy fuerte de la columna de agua, con temperaturas superficiales de hasta >31 oC, que disminuye en gran medida el transporte vertical del agua cerca de la costa de Baja California. La TSS tiene una tendencia general de aumentar de la costa occidental del Golfo hacia la oriental, con un gradientc débil dc uno a dos grados a través de todo el Golfo (de 29 "C en la costa occidental a 31 "C en la oriental). Los valores dc Chl,al muestran un gradiente invcrso, con valores mayores cerca de la costa occidental del Golfo (hasta 0.2 mg m J) y disminuyendo a <0.1 mg m-l frente a la costa oriental. En algunos casos se mostraron lenguetas y remolinos claros, como los remolinos ciclónicos observados en la distribución de TSS con núcleus de 28 oc. Una Jcngucta de valores relativamente altos de Chl ..., (-0.2 mg m-J) indicó advección de Baja California hacia Sonora en la parte norte de nuestra zona de estudio.
Ocean color (OCTS, SeaWiFS) and sea surface temperature (AVHRR) images were used to evaluate spat... more Ocean color (OCTS, SeaWiFS) and sea surface temperature (AVHRR) images were used to evaluate spatial and temporal variability of the Brazil‐Malvinas Confluence and La Plata Plume (20° to 45°S and 40° to 65°W). The data set covers the period from January 1997 to June 2003. Chlorophyll and SST data were combined using Principal Component Analysis (PCA). The results yielded were used to identify and follow front displacements. PCA maps showed a close relationship with previous observations of currents behavior and the La Plata Plume. Firstly the analysis was performed on data retrieved from a monthly climatology, and the results show three remarkable features: a gradual increase of the northward intrusion of the La Plata Plume throughout the period lasting from summer to winter; the summer shape of the La Plata Plume showed a stronger penetration over the shelf on the Argentinean side of the estuary mouth; and the seasonal migration of the Brazil‐Malvinas Confluence. Monthly composites...
Surface mesoscale structures and wind variability in the northern Gulf of California (NGC) were a... more Surface mesoscale structures and wind variability in the northern Gulf of California (NGC) were analyzed using data from SeaWiFS (1 km) and QuikSCAT (1 day). The months of February and March were selected as representative of winter and the months of August and September were selected as representative of summer. Chlorophyll‐a (Chla) and wind time series were constructed using 16 points to analyze temporal variability and wind magnitude‐Chla temporal and spatial linear correlation. Wind components along and across the NGC were found to play an equally significant role regarding wind variability, contrary to what is currently recognized. Wind magnitude tended to be stronger in winter and had less wind direction variability than in summer. A bimodal wind pattern was registered for each season, each wind direction explaining less than 30% of total variability. The zone with minimum variability in wind direction and maximum variability in wind magnitude was located northwest of the NGC,...
Deep Sea Research Part II: Topical Studies in Oceanography, 2004
SeaWiFS high-resolution ocean-color images and AVHRR sea-surface temperature were obtained for th... more SeaWiFS high-resolution ocean-color images and AVHRR sea-surface temperature were obtained for the period from November 1998 to March 1999. Generation of mesoscale eddies was observed for the region between the Gulf of Tehuantepec and the Gulf of Papagayo (Tropical Pacific Ocean). Eighteen eddies with diameters ranging between 100 and 450 km were identified; 14 originated in the Gulf of Tehuantepec and most were cyclonic. Our results show that the frequency of cyclonic eddy formation is higher than it has been reported and their lifetime can be longer. Using both ocean color images and daily temporal resolution, instead of sea-surface temperature alone, improved our ability to identify and follow the propagation of these eddies. The generation and fate of smaller cyclonic eddies around the periphery of the anticyclonic eddy indicate the importance of the onshore-offshore exchange of energy and biological material, which has not been considered previously. Three anticyclonic eddies were generated in the Gulf of Papagayo. These eddies have a common origin, and they travel along the main flux of the Costa Rica Coastal Current (CRCC), which later turns offshore and joins the North Equatorial Current. This behavior can be seen clearly on SeaWiFS images and suggests that the CRCC influences eddy propagation. Time series of chlorophyll-a concentration and SST were obtained from two points at Tehuantepec and two at Papagayo. Cross-correlation analysis confirms an inverse relationship between these variables, showing that a decrease in SST is followed by an increase in chlorophyll-a concentration values, indicating high growth and primary production rates.
Deep Sea Research Part II: Topical Studies in Oceanography, 2004
From 15 to 19 October 1994, an oceanographic cruise was carried out in the Gulf of California. Ph... more From 15 to 19 October 1994, an oceanographic cruise was carried out in the Gulf of California. Phytoplankton biovolume, pigment concentrations, and taxonomy were examined as functions of location and light depth. The specific absorption coefficient of phytoplankton (a>h) showed variability in magnitude and spectral shapes between stations and with depth. The a*ph values ranged from 0.020-0.056 m2(mg chl a)-' at 440 nm to 0.013-0.020 m2(mg chl a)-' at 674 nm. Spectra of phytoplankton belonging to the same taxonomic group tended to have similar shape. At stations where the environmental conditions favored the presence of microphytoplankton populations (cells >20 pm), the lowest a* were found. Of all the variables studied, pigments, particularly the photoprotective pigment zeaxanthin, had the highest correlation with u*ph. Changes in pigment composition and cellular concentration were responsible for over 70% of the variability of the specific absorption at 440 nm. Including biovolume per cell in a multiple regression improved the model to explain up to 80% of a*ph variations. The work described here concurrently examined pigment packaging, measured as the cellular concentration of chlorophyll a and as the phytoplankton cell volume, and the confounding effect of the blue-absorbing accessory pigments on the specific absorption coefficient. The a;,, varied as a function of all three variables, indicating the importance of both taxonomic variations (size and accessory pigments) as well as responses to environmental variations.
ABSTRACT A dynamic regionalization of the Gulf of Mexico (GoM) was carried out based on normalize... more ABSTRACT A dynamic regionalization of the Gulf of Mexico (GoM) was carried out based on normalized radiances derived from MODIS-Aqua while considering its seasonal variability (Hurricane and Non-hurricane seasons). Daily images with a 1 km resolution from June 2002 to May 2007 were used. To define the dynamic regions, the first Standard Empirical Orthogonal Function (SEOF1) was calculated by combining nLw412 nm and nLw488 nm. The GoM was divided into two large provinces: oceanic and coastal. Within the oceanic province there are three regions with oligotrophic conditions. The coastal province displayed two sub-provinces (the northern and southern Gulf of Mexico) within which eight regions were located. Two of them were classified as transition regions. In general, most regions could be associated with general circulation patterns and/or river discharge influence. When looking at changes in coverage and the number of divisions, this regionalization shows a bi-seasonal modulation governed by hurricane seasons. The approximation presented here allows the dynamic regionalization of the GoM, a zone characterized by small surface gradients on Chl a and SST, including the recognition of smaller structures such as eddies.
This article was published in an Elsevier journal. The attached copy is furnished to the author f... more This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:
Tropical and subtropical Atlantic Ocean waters off the coasts of Brazil, Uruguay and Argentina ar... more Tropical and subtropical Atlantic Ocean waters off the coasts of Brazil, Uruguay and Argentina are influenced by a variety of hydrographic processes that lead to a great diversity in the biological system. In situ observations are scarce and sparsely distributed over this zone. Phytoplankton pigment concentrations were estimated utilizing the Coastal Zone Colour Scanner for the area located between 5 N and 45 S, and from the coast of South America eastward to 25 W. Advanced Very High Resolution Radiometer (sea surface temperature) and data from literature were used to differentiate regions, considering space and time variations of the phytoplankton biomass. Monthly pigment concentration time series were used for the period of January 1982-May 1986 as input for a Principal Component Analysis (PCA). The PCA analysis grouped 152 locations into 14 regions, most of them associated to clear surface circulation patterns and hydrographic features. These results were confirmed using monthly composites of chlorophylla concentration from Sea-viewing Wide Field-of-view Sensor for the period September 1997-April 2002. A connection between the 1982/83 and 1997/98 ENSO events and pigment distribution over southern and southeastern Brazil, as well as the Argentinean continental shelf, was clearly evidenced in temporal pigment distributions. Results presented in this work contribute to the idea that ocean colour images are an appropriate tool to identify and follow the seasonal displacement of biogeographical region boundaries.
Le contexte actuel de la confrontation armee en Colombie montre sur le terrain une diversite d... more Le contexte actuel de la confrontation armee en Colombie montre sur le terrain une diversite d'acteurs illegaux qu'actionnent de maniere indeterminee, tout en produisant des ruptures institutionnelles et sociales. Cette realite met en evidence la necessite pour l'Etat de mettre en œuvre les instruments permettant non seulement la reconstruction des tissus social et institutionnel, mais aussi pour mettre fin au conflit arme et assurer la reinsertion a la vie civile des acteurs armes. Cela est le constat d'une impossible " politique d'Etat " de reinsertion. Le politiques de paix transitoires sont a l'origine des ces consequences nefastes. La reinsertion des combattants se voit limitee a des instruments juridiques tels que l'amnistie et la grâce, sans tenir compte des causes qui etaient a l'origine de la confrontation. Ainsi, la gauche et la droite ont toujours hesite entre la solution negociee du conflit ou la confrontation armee. Entre tant les acteurs armes ont developpe leurs propres machines de guerre et ont deploye des strategies d'expansion tres efficace. Le budget general du programme national de reinsertion est tres maigre par rapport aux besoins socio-economiques des combattants, sans tenir compte des difficultes materielles pour leur execution. Le modele actuel de reinsertion reste encore a developper, a ameliorer. Dans cette recherche, nous voulions non seulement determiner les causes du conflit et la necessite de reinsertion des acteurs armes, mais aussi identifier les manques et les deficiences des programmes de reinsertion, pour nous approcher a une solution.
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