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Author: JULIAN JORGE ADEM CHAHIN

On the seasonal effect of orbital variations on the climates of the next 4000 years

JULIAN JORGE ADEM CHAHIN (1996)

A northern hemisphere thermodynamic climate model is used to compute the effect of the insolation anomalies due to orbital variations in the climates for the next 4000 years. Berger's mean monthly anomalies of insolation are used in the computations, which are carried out for 1000, 2000, 3000 and 4000 years after present (kyears AP). The numerical simulations show that in the climates of the next 4000 years, due to the effect of the orbital variations, springs and summers will be increasingly dryer and falls and winters wetter than the present climate.

Article

On the seasonal effect of orbital variations on the climates of the next 4000 years

JULIAN JORGE ADEM CHAHIN (1996)

A northern hemisphere thermodynamic climate model is used to compute the effect of the insolation anomalies due to orbital variations in the climates for the next 4000 years. Berger's mean monthly anomalies of insolation are used in the computations, which are carried out for 1000, 2000, 3000 and 4000 years after present (kyears AP). The numerical simulations show that in the climates of the next 4000 years, due to the effect of the orbital variations, springs and summers will be increasingly dryer and falls and winters wetter than the present climate.

Article

On the asymptotic behaviour of the Adem Thermodynamic Model for the ocean temperature prediction

TOMAS MORALES ACOLTZI JULIAN JORGE ADEM CHAHIN (1994)

The asymptotic behaviour of Adem's model is analyzed as a function of the external forcing and the dissipation coefficient. The existence of a bounded attracting set of the sea surface temperature anomalies in a neighborhood of zero is proved. It is shown that the perturbation solution decays exponentially to zero, under a certain condition. The decay rate depends on the external forcing and the turbulent coefficient.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO

On the asymptotic behaviour of the Adem Thermodynamic Model for the ocean temperature prediction

TOMAS MORALES ACOLTZI JULIAN JORGE ADEM CHAHIN (1994)

The asymptotic behaviour of Adem's model is analyzed as a function of the external forcing and the dissipation coefficient. The existence of a bounded attracting set of the sea surface temperature anomalies in a neighborhood of zero is proved. It is shown that the perturbation solution decays exponentially to zero, under a certain condition. The decay rate depends on the external forcing and the turbulent coefficient.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA CIENCIAS DE LA TIERRA Y DEL ESPACIO

Sea surface temperature and mixed layer depth changes due to cold-air outbreak in the gulf of México

ELBA ELSA VILLANUEVA URRUTIA VICTOR MANUEL MENDOZA CASTRO JULIAN JORGE ADEM CHAHIN (2010)

The impact of a cold-air outbreak (CAO) on the mixed layer in the Gulf of México (GoM), during the period 18-23 October 1999, is shown in this work. A numerical model, based on the thermal energy equation and the balance equation between the thermal and mechanical energies, is used for computing both, the sea surface temperature (SST) and the sea mixed layer depth (MLD) changes due to atmospheric forcing before and during the CAO. The importance of the contributions to the temperature tendency by thermal forcing at the surface, the vertical entrainment of cold water from the thermocline, the horizontal transport of thermal energy by ocean currents and by turbulent eddies in the mixed layer are analyzed, as well as the contributions to the entrainment velocity by deepening of the mixed layer and the Ekman's pumping velocity. During the passage of the CAO on the Gulf of México the SST changes were markedly influenced by the increase in the surface wind speed. At the end of the period the experiments show that the vertical entrainment turned out to be the most determining process in the cooling of the mixed layer, even overhead of the latent and sensible heat fluxes and the horizontal transport by ocean currents and by turbulent eddies.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Sea surface temperature mixed layer depth cold-air outbreak Gulf of México

On the simulation of the sea surface temperature in the Gulf of Mexico using a thermodynamic model

JULIAN JORGE ADEM CHAHIN VICTOR MANUEL MENDOZA CASTRO ELBA ELSA VILLANUEVA URRUTIA MARIA ADELA MONREAL GOMEZ (1991)

A thermodynamic model is used to simulate the annual cycle of the sea surface temperature (SST) in the Gulf of The model includes as the basic equation the thermal energy equation applied to the upper mixed layer of the ocean This equation is vertically integrated and includes the horizontal transport of heat by mean ocean currents and by turbulent eddies, as well as the heating by radiation, sensible heat given off to the atmosphere and evaporation. The thermodynamic model is adapted, by using a regular grid with a distance of 60 km between adjacent points covering the whole area of the Gulf of Mexico. In these numerical experiments the observed surface currents and the horizontal transport of heat through the Yucatan Channel are used as prescribed fields, as well as the atmospheric conditions. An objective comparison of the values of the computed SST with those observed, shows a good agreement.

Article

Some numerical solutions of the barotropic vorticity equation applied to the Gulf of Mexico

ELBA ELSA VILLANUEVA URRUTIA VICTOR MANUEL MENDOZA CASTRO JULIAN JORGE ADEM CHAHIN (2002)

Numerical solutions of the barotropic vorticity equation under forcing by wind stress, and mass transport between the basins of the Caribbean Sea and the Gulf of Mexico, are shown, in the first part of this study, the equation was solved for a steady flow with a flat bottom of 200m depth, realistic coastlines and horizontal resolution of 25 km. In the second part, we added the bottom bathymetry, and the equation was solved for the steady-state and non-steady-state. In the non-steady regime, we found that the Loop Current (LC) penetrates into the Gulf and bend westward into unstable configuration to give rise to a periodic eddy shedding regime, in which the anticyclonic eddies are shedded of the Loop Current and propagated westward as solitary Rossby waves. The lifetime of these anticyclonic eddies is about of 120 days; they have a size from 275 to 440 km and propagation speed of about 7.3 km day-1.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Barotropic Vorticity Equation Eddy Shedding Gulf of México

Effect of an axially-symmetric cyclonic vortex on the sea surface temperature in the Gulf of México

ELBA ELSA VILLANUEVA URRUTIA VICTOR MANUEL MENDOZA CASTRO JULIAN JORGE ADEM CHAHIN (2006)

A model for the mixed layer of the Gulf of México has been used to determine the effect that an idealized cyclonic vortex has in the sea surface temperature. The model consists of the equations of conservation of thermal energy and this of balance between mechanical energy and thermal energy, last based on the Kraus- Turner theory; both equations are vertically integrated in the mixed layer. As atmospheric forcing, we prescribe the surface wind associated with an axially-symmetric cyclonic vortex characterized by two parameters: the maximum tangential velocity and the radius at which that velocity is reached. The values of these two parameters, which depend on the position of the vortex, correspond to two cases: hurricane Hilda, which crossed the central part of the Gulf of México between September 29 and October 3, 1964 and hurricane Gilbert whose trajectory between 11 and 17 September, 1988 crossed the Caribbean Sea, the Yucatán Peninsula and the southwest Gulf of México. The results show that a cyclonic vortex with such characteristics, produce during its passage by the sea vertical turbulent water transport through the thermocline (entrainment) that is able to cool down the mixed layer in several degrees and increases the thermocline depth in several meters, in agreement with the observations.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Gulf of México sea surface temperature mixed layer numerical model atmospheric forcing entrainment

Vulnerability of basins and watersheds in Mexico to global climate change

VICTOR MANUEL MENDOZA CASTRO ELBA ELSA VILLANUEVA URRUTIA JULIAN JORGE ADEM CHAHIN (1997)

Some conclusions on the vulnerability of hydrologic regions in Mexico to future changes in climate can be drawn from the application of regional-scale thermal-hydrological models. Climate changes induced by the doubling of atmospheric CO2 have been predicted for the year 2050 by general circulation models (GCMs) and energy balance models (EBMs). The results obtained suggest that potential changes in air temperature and precipitation may have a dramatic impact on the pattern and magnitude of runoff, on soil moisture and evaporation, as well as on the aridity level of some hydrologic zones of Mexico. However, in other cases climate change is likely to produce a positive effect. Indices were estimated for quantifying the vulnerability of hydrologic regions and of the country as a whole. These vulnerability indices were defined according to criteria previously established for studies of this type. The indices provide information about both the hydrologic zones which are vulnerable even under current climate conditions and others which may be vulnerable to future climate changes.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA Mexico Thermal balance Hydrological balance Climate change Vulnerability Hidrology

On the simulation of the sea surface temperature in the Gulf of Mexico using a thermodynamic model

JULIAN JORGE ADEM CHAHIN VICTOR MANUEL MENDOZA CASTRO ELBA ELSA VILLANUEVA URRUTIA MARIA ADELA MONREAL GOMEZ (1991)

A thermodynamic model is used to simulate the annual cycle of the sea surface temperature (SST) in the Gulf of The model includes as the basic equation the thermal energy equation applied to the upper mixed layer of the ocean This equation is vertically integrated and includes the horizontal transport of heat by mean ocean currents and by turbulent eddies, as well as the heating by radiation, sensible heat given off to the atmosphere and evaporation. The thermodynamic model is adapted, by using a regular grid with a distance of 60 km between adjacent points covering the whole area of the Gulf of Mexico. In these numerical experiments the observed surface currents and the horizontal transport of heat through the Yucatan Channel are used as prescribed fields, as well as the atmospheric conditions. An objective comparison of the values of the computed SST with those observed, shows a good agreement.

Article