Advections polaires en Bolivie : mise en évidence et caractérisation des effets climatiques

En Bolivie, les advections polaires sont des phénomènes apériodiques, quatre fois plus fréquents en hiver qu'en été. Leurs effets pluviométriques et thermiques sont différents d'une saison à l'autre et ils sont surtout notables dans les vallées andines du sud du pays à exposition favorable et dans la plaine où ils sont ressentis jusqu'à moins 10° de latitude sud. (Résumé d'auteur

3. Eventos hidrológicos extremos en la cuenca amazónica peruana: presente y futuro

Recientemente, severos eventos hidrológicos extremos han ocurrido en el Río Amazonas, como intensas sequías e inundaciones, las cuales han perjudicado a las principales ciudades amazónicas y a las zonas rurales. Esos eventos hacen parte de una tendencia hacia estiajes siempre más bajos. Mientras que el caudal más bajo fue observado en septiembre de 2010 (8 300m3/s) en la estación hidrométrica de Tamshiyacu, una rápida transición hacia uno de los caudales más altos fue observado en abril 2011 (45 000 m3/s). Finalmente en abril de 2012, durante el siguiente periodo de aguas altas, el Río Amazonas experimentó su caudal histórico más elevado (55 400m3/s). Los modelos climatológicos e hidrológicos permiten prever caudales futuros. Para la mitad del siglo 21 se calcula un aumento de 7% de los caudales de crecida, lo que significa extremos aún mayores que los actuales e inundaciones más amplias.La région du fleuve Amazone a récemment connu de sévères événements hydrologiques extrêmes: des inondations et des sécheresses qui ont porté préjudice tant aux villes amazoniennes qu’aux zones rurales. Ces événements s’inscrivent dans une tendance vers des étiages toujours plus prononcés. Alors que le débit le plus bas a été observé en septembre 2008 (8 300 m3/s) a la station hydrométrique de Tamshiyacu, celui-ci a été rapidement suivi d’une rapide transition vers l’un des débits les plus hauts en avril 2011 (45 000 m3/s). Finalement en avril 2012, lors de la saison suivante de hautes eaux, le fleuve Amazone a présenté un débit historique très élevé (55 400 m3/s). Les modelés climatologiques et hydrologiques permettent de prévoir les débits futurs. D’ici la moitié du 21ème siècle, on estime qu’il y aura une augmentation de 7% des débits de crue, ce qui signifie des extrêmes encore plus élevés qu’actuellement et des inondations de plus grande ampleur.The Amazon River has recently experienced severe extreme hydrological events -such as floods and droughts- that have harmed both the main Amazonian cities as rural areas. These events are part of a continuous trend towards low flow. While the lowest rate was observed in September 2008 (8,300 m3/s) at the Tamshiyacu hydrometric station, it was observed a rapid transition to one of the highest rates in April 2011 (45,000m3/s). In April 2012, during the next period of high water, the Amazon River experienced it highest flow in its history (55 400 m3/s). Climatological and hydrological models are used to predict future rates. An increase of 7% of flood flows is calculated by the middle of the 21st century, which means even greater extreme floods than the current ones and larger

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

A physiological time analysis of the duration of the gonotrophic cycle of Anopheles pseudopunctipennis and its implications for malaria transmission in Bolivia

<p>Abstract</p> <p>Background</p> <p>The length of the gonotrophic cycle varies the vectorial capacity of a mosquito vector and therefore its exact estimation is important in epidemiological modelling. Because the gonotrophic cycle length depends on temperature, its estimation can be satisfactorily computed by means of physiological time analysis.</p> <p>Methods</p> <p>A model of physiological time was developed and calibrated for <it>Anopheles pseudopunctipennis</it>, one of the main malaria vectors in South America, using data from laboratory temperature controlled experiments. The model was validated under varying temperatures and could predict the time elapsed from blood engorgement to oviposition according to the temperature.</p> <p>Results</p> <p>In laboratory experiments, a batch of <it>An. pseudopunctipennis </it>fed at the same time may lay eggs during several consecutive nights (2–3 at high temperature and > 10 at low temperature). The model took into account such pattern and was used to predict the range of the gonotrophic cycle duration of <it>An. pseudopunctipennis </it>in four characteristic sites of Bolivia. It showed that the predicted cycle duration for <it>An. pseudopunctipennis </it>exhibited a seasonal pattern, with higher variances where climatic conditions were less stable. Predicted mean values of the (minimum) duration ranged from 3.3 days up to > 10 days, depending on the season and the geographical location. The analysis of ovaries development stages of field collected biting mosquitoes indicated that the phase 1 of Beklemishev might be of significant duration for <it>An. pseudopunctipennis</it>. The gonotrophic cycle length of <it>An. pseudopunctipennis </it>correlates with malaria transmission patterns observed in Bolivia which depend on locations and seasons.</p> <p>Conclusion</p> <p>A new presentation of cycle length results taking into account the number of ovipositing nights and the proportion of mosquitoes laying eggs is suggested. The present approach using physiological time analysis might serve as an outline to other similar studies and allows the inclusion of temperature effects on the gonotrophic cycle in transmission models. However, to better explore the effects of temperature on malaria transmission, the others parameters of the vectorial capacity should be included in the analysis and modelled accordingly.</p