scholarly journals Climate variability and seasonal patterns of paediatric parainfluenza infections in the tropics: An ecological study in Singapore

Author(s):  
Stacy Soh ◽  
Liat Hui Loo ◽  
Natasha Jamali ◽  
Matthias Maiwald ◽  
Joel Aik
2015 ◽  
Vol 12 (3) ◽  
pp. 835-844 ◽  
Author(s):  
P. J. Rayner ◽  
A. Stavert ◽  
M. Scholze ◽  
A. Ahlström ◽  
C. E. Allison ◽  
...  

Abstract. We analyse global and regional changes in CO2 fluxes using two simple models, an airborne fraction of anthropogenic emissions and a linear relationship with CO2 concentrations. We show that both models are able to fit the non-anthropogenic (hereafter natural) flux over the length of the atmospheric concentration record. Analysis of the linear model (including its uncertainties) suggests no significant decrease in the response of the natural carbon cycle. Recent data points rather to an increase. We apply the same linear diagnostic to fluxes from atmospheric inversions. Flux responses show clear regional and seasonal patterns driven by terrestrial uptake in the northern summer. Ocean fluxes show little or no linear response. Terrestrial models show clear responses, agreeing globally with the inversion responses, however the spatial structure is quite different, with dominant responses in the tropics rather than the northern extratropics.


2011 ◽  
Vol 7 (3) ◽  
pp. 757-770 ◽  
Author(s):  
R. Y. Anderson

Abstract. A continuous series of 209 000 evaporite varves from the equator of arid western Pangea (age = −255 ma), as a proxy for surface temperature, has a complete suite of Milankovitch cycles and harmonics as expected for a rectified reaction to precession-modulated insolation at the equator. Included are modes of precession (23.4 kyr, 18.2 kyr), semi-precession (11.7 kyr, 9.4 kyr), and harmonics at ~7 kyr and 5.4 kyr. An oscillation of ~100 kyr, with 35 % of total variance, originates as an amplitude modulation of precession cycles. An exceptionally strong 2.3 kyr quasi-bi-millennial oscillation (QBMO) appears to have had its own source of forcing, possibly solar, with its amplitude enhanced at Milankovitch frequencies. Seasonal information in varves traces the rectifying process to asymmetrical distribution of Pangea relative to the equator, and its effect on monsoonal circulation and heat flow near the equator during summer solstices in the hemispheres.


2020 ◽  
Author(s):  
Matthieu Lengaigne ◽  

<p>Ocean-atmosphere interactions in the tropics have a profound influence on the climate system. El Niño–Southern Oscillation (ENSO), which is spawned in the tropical Pacific, is the most prominent and well-known year-to-year variation on Earth. Its reach is global, and its impacts on society and the environment are legion. Because ENSO is so strong, it can excite other modes of climate variability in the Indian Ocean by altering the general circulation of the atmosphere. However, ocean-atmosphere interactions internal to the Indian Ocean are capable of generating distinct modes of climate variability as well. Whether the Indian Ocean can feedback onto Atlantic and Pacific climate has been an on-going matter of debate. We are now beginning to realize that the tropics, as a whole, are a tightly inter-connected system, with strong feedbacks from the Indian and Atlantic Oceans onto the Pacific. These two-way interactions affect the character of ENSO and Pacific decadal variability and shed new light on the recent hiatus in global warming.</p><p>Here we review advances in our understanding of pantropical interbasins climate interactions with the Indian Ocean and their implications for both climate prediction and future climate projections. ENSO events force changes in the Indian Ocean than can feed back onto the Pacific. Along with reduced summer monsoon rainfall over the Indian subcontinent, a developing El Niño can trigger a positive Indian Ocean Dipole (IOD) in fall and an Indian Ocean Basinwide (IOB) warming in winter and spring. Both IOD and IOB can feed back onto ENSO. For example, a positive IOD can favor the onset of El Niño, and an El Niño–forced IOB can accelerate the demise of an El Niño and its transition to La Niña. These tropical interbasin linkages however vary on decadal time scales. Warming during a positive phase of Atlantic Multidecadal Variability over the past two decades has strengthened the Atlantic forcing of the Indo-Pacific, leading to an unprecedented intensification of the Pacific trade winds, cooling of the tropical Pacific, and warming of the Indian Ocean. These interactions forced from the tropical Atlantic were largely responsible for the recent hiatus in global surface warming.</p><p>Climate modeling studies to address these issues are unfortunately compromised by pronounced systematic errors in the tropics that severely suppress interactions with the Indian and Pacific Oceans. As a result, there could be considerable uncertainty in future projections of Indo-Pacific climate variability and the background conditions in which it is embedded. Projections based on the current generation of climate models suggest that Indo-Pacific mean-state changes will involve slower warming in the eastern than in the western Indian Ocean. Given the presumed strength of the Atlantic influence on the pantropics, projections of future climate change could be substantially different if systematic model errors in the Atlantic were corrected. There is hence tremendous potential for improving seasonal to decadal climate predictions and for improving projections of future climate change in the tropics though advances in our understanding of the dynamics that govern interbasin linkages.</p>


2005 ◽  
Vol 16 (2) ◽  
pp. 71-74
Author(s):  
Andrew Challinor ◽  
Tim Wheeler ◽  
Julia Slingo ◽  
Tom Osborne

2021 ◽  
Vol 4 ◽  
Author(s):  
Alan M. Tonin ◽  
Laís S. Lima ◽  
Paulino Bambi ◽  
Monique L. Figueiredo ◽  
Renan S. Rezende ◽  
...  

Litterfall has a large influence on carbon and nutrient cycling of ecosystems, particularly in light-limited forested streams, as most nutrients return in the form of litter. Although recent evidence points to the prevalence of seasonal litterfall in species-rich and evergreen tropical riparian forests, there is a limited understanding of how riparian plant diversity intersects with stream and riparian ecosystem functions. To explore this question, we investigate litterfall chemistry across wet and dry seasons and the congruence between litter traits and plant species composition of litterfall in the wet-dry tropics. Using generalized additive models, we observed consistent seasonal patterns of litterfall chemistry over 2 years, mostly influenced by dominant species in litterfall. While drier seasons showed litter lower in nutrients and structural compounds and higher in polyphenols, litter from wetter seasons were nutrient rich but lower in polyphenols. We also found contrasting seasonal patterns in litterfall chemistry, one showing that litterfall nutrient, structural compounds, and secondary metabolite concentrations declined in drier seasons while the other showed that mass-based litterfall inputs increased markedly in drier seasons. Our findings suggest that litterfall chemistry may be altered by shifts in the identity of dominant plant species and seasonality, possibly leading to changes in carbon and nutrient fluxes in tropical riparian ecosystems.


2019 ◽  
Vol 176 ◽  
pp. 108523 ◽  
Author(s):  
Pandji Wibawa Dhewantara ◽  
Wenbiao Hu ◽  
Wenyi Zhang ◽  
Wen-Wu Yin ◽  
Fan Ding ◽  
...  

2001 ◽  
Vol 49 (1-4) ◽  
pp. 1-6 ◽  
Author(s):  
S.M McKinnell ◽  
R.D Brodeur ◽  
K Hanawa ◽  
A.B Hollowed ◽  
J.J Polovina ◽  
...  

2011 ◽  
Vol 8 (64) ◽  
pp. 1584-1593 ◽  
Author(s):  
Virginia E. Pitzer ◽  
Cécile Viboud ◽  
Ben A. Lopman ◽  
Manish M. Patel ◽  
Umesh D. Parashar ◽  
...  

Rotavirus is a major cause of mortality in developing countries, and yet the dynamics of rotavirus in such settings are poorly understood. Rotavirus is typically less seasonal in the tropics, although recent observational studies have challenged the universality of this pattern. While numerous studies have examined the association between environmental factors and rotavirus incidence, here we explore the role of intrinsic factors. By fitting a mathematical model of rotavirus transmission dynamics to published age distributions of cases from 15 countries, we obtain estimates of local transmission rates. Model-predicted patterns of seasonal incidence based solely on differences in birth rates and transmission rates are significantly correlated with those observed (Spearman's ρ = 0.65, p < 0.05). We then examine seasonal patterns of rotavirus predicted across a range of different birth rates and transmission rates and explore how vaccination may impact these patterns. Our results suggest that the relative lack of rotavirus seasonality observed in many tropical countries may be due to the high birth rates and transmission rates typical of developing countries rather than being driven primarily by environmental conditions. While vaccination is expected to decrease the overall burden of disease, it may increase the degree of seasonal variation in the incidence of rotavirus in some settings.


2014 ◽  
Vol 41 (3) ◽  
pp. 969-975 ◽  
Author(s):  
Kelly Ann Gibson ◽  
Larry C. Peterson

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