Abstract. We present estimates of turbulent fluxes of heat and momentum derived from low level (∼30 m) aircraft measurements over the tropical Eastern Pacific and provide empirical relationships that are valid under high wind speed conditions (up to 25 ms −1 ). The estimates of total momentum flux and turbulent kinetic energy can be represented very accurately (r 2 =0.99, when data are binned every 1 ms −1 ) by empirical fits with a linear and a cubic terms of the average horizontal wind speed. The latent heat flux shows a strong quadratic dependence on the horizontal wind speed and a linear relationship with the difference between the air specific humidity and the saturated specific humidity at the sea surface, explaining 96% of the variance. The estimated values were used to evaluate the performance of three currently used parameterizations of turbulence fluxes, varying in complexity and computational requirements. The comparisons with the two more complex parameterizations show good agreement between the observed and parameterized latent heat fluxes, with less agreement in the sensible heat fluxes, and one of them largely overestimating the momentum fluxes. A third, very simple parameterization shows a surprisingly good agreement of the sensible heat flux, while momentum fluxes are again overestimated and a poor agreement was observed for the latent heat flux (r 2 =0.62). The performance of all three parameterizations deteriorates significantly in the high wind speed regime (above 10-15 ms −1 ). The dataset obtained over the tropical Eastern Pacific allows us to derive empirical functions for the turbulent fluxes that are applicable from 1 to 25 ms −1 , which can be introduced in meteorological models under high wind conditions.
At present, many coastal ecosystems worldwide are highly affected by anthropic activities. La Mancha lagoon, in the state of Veracruz, Mexico, is an important ecosystem due to the wide array of ecosystem services that it provides. In this paper, an analysis of the environmental balances of the lagoon is outlined, using the Drivers, Exchanges, State of the Environment, Consequences and Responses (DESCR) tool. The methodological framework considers the interrelationships between the natural systems and the forces of change that alter the performance of the natural environment, in order to provide an overview of actions that may reduce negative consequences. The study area has been impacted by anthropic development, such as changes in land use for agricultural and livestock activities, loss of mangroves due to logging and modifications, carried out by local fishermen, to the natural hydrodynamics of the lagoon that alter the salinity and affect the ecosystem dynamics. Following analysis of the area, using the DESCR tool, the responses proposed include long-term environmental impact evaluation, with the aim of preserving the local coastal ecosystems.
The great importance of mangroves’ forest is linked to their capacity of resilience against natural and human impacts, this way playing a determinant function in the adaptation to climatic change related processes. At global scale, mangroves’ forests cover an area of 150,000 km2, 11% (≈16,500 km2) of them being located along the Pacific and Caribbean coasts of South America. About 70 species of mangroves exist around the World with 10 observed in South America, among them the most relevant are: Rhizophora mangle, Avicennia germinans, Laguncularia racemosa and Conocarpus erectus. Concerning mangroves’ cover loss, at global scale, an annual rate of 0.16% was observed between 2000 and 2012 with lower rates recorded in South America respect to Asia, Africa, North and Central America. This paper analyses the main effects of natural and human impacts on mangroves’ forests by means of examples from South America and several other countries. Concerning natural impacts special attention was devoted to: i) constant and ii) specific erosion processes (related to storms and tropical cyclones), both of them essentially affect Rizophora mangle since this specie occurs at the shoreline meanwhile strong winds recorded during hurricanes (with a category > 3 of the Saffir-Simpson scale) especially affects R. mangle and A. germinans, and iii) the effects of climatic phenomena such as “El Niño” and “La Niña” that produce variations in soil salinity that determinates the establishment and growth of a mangrove’s specie or an other. Concerning human impacts special attention was paid to illegal logging that, in the Northern Caribbean of Colombian coast essentially affectes L. racemosa, which wood is used by local population to build up cabins on the beaches for tourist purposes. Keywords: Coastal erosion, Hurricane, El Niño, Deforestation, Salinity.
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