| 1. |
- Mann, G. W., et al.
(författare)
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Intercomparison and evaluation of global aerosol microphysical properties among AeroCom models of a range of complexity
- 2014
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:9, s. 4679-4713
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Tidskriftsartikel (refereegranskat)abstract
- Many of the next generation of global climate models will include aerosol schemes which explicitly simulate the microphysical processes that determine the particle size distribution. These models enable aerosol optical properties and cloud condensation nuclei (CCN) concentrations to be determined by fundamental aerosol processes, which should lead to a more physically based simulation of aerosol direct and indirect radiative forcings. This study examines the global variation in particle size distribution simulated by 12 global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from a new European network of aerosol supersites shows that the mean model agrees quite well with the observations at many sites on the annual mean, but there are some seasonal biases common to many sites. In particular, at many of these European sites, the accumulation mode number concentration is biased low during winter and Aitken mode concentrations tend to be overestimated in winter and underestimated in summer. At high northern latitudes, the models strongly underpredict Aitken and accumulation particle concentrations compared to the measurements, consistent with previous studies that have highlighted the poor performance of global aerosol models in the Arctic. In the marine boundary layer, the models capture the observed meridional variation in the size distribution, which is dominated by the Aitken mode at high latitudes, with an increasing concentration of accumulation particles with decreasing latitude. Considering vertical profiles, the models reproduce the observed peak in total particle concentrations in the upper troposphere due to new particle formation, although modelled peak concentrations tend to be biased high over Europe. Overall, the multimodel-mean data set simulates the global variation of the particle size distribution with a good degree of skill, suggesting that most of the individual global aerosol microphysics models are performing well, although the large model diversity indicates that some models are in poor agreement with the observations. Further work is required to better constrain size-resolved primary and secondary particle number sources, and an improved understanding of nucleation and growth (e. g. the role of nitrate and secondary organics) will improve the fidelity of simulated particle size distributions.
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| 2. |
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| 3. |
- Alström, Per, et al.
(författare)
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Integrative taxonomy of the Plain-backed Thrush (Zoothera mollissima) complex (Aves, Turdidae) reveals cryptic species, including a new species.
- 2016
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Ingår i: Avian research. - : Elsevier BV. - 2053-7166. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The Plain-backed Thrush Zoothera mollissima breeds in the Himalayas and mountains of central China. It was long considered conspecific with the Long-tailed Thrush Zoothera dixoni, until these were shown to be broadly sympatric. Methods: We revise the Z. mollissima–Z. dixoni complex by integrating morphological, acoustic, genetic (two mito- chondrial and two nuclear markers), ecological and distributional datasets. Results: In earlier field observations, we noted two very different song types of“Plain-backed”Thrush segregated by breeding habitat and elevation. Further integrative analyses congruently identify three groups: an alpine breeder in the Himalayas and Sichuan, China (“Alpine Thrush”); a forest breeder in the eastern Himalayas and northwest Yunnan (at least), China (“Himalayan Forest Thrush”); and a forest breeder in central Sichuan (“Sichuan Forest Thrush”). Alpine and Himalayan Forest Thrushes are broadly sympatric, but segregated by habitat and altitude, and the same is prob- ably true also for Alpine and Sichuan Forest Thrushes. These three groups differ markedly in morphology and songs. In addition, DNA sequence data from three non-breeding specimens from Yunnan indicate that yet another lineage exists (“Yunnan Thrush”). However, we find no consistent morphological differences from Alpine Thrush, and its breed- ing range is unknown. Molecular phylogenetic analyses suggest that all four groups diverged at least a few million years ago, and identify Alpine Thrush and the putative “Yunnan Thrush” as sisters, and the two forest taxa as sisters. Cytochrome b divergences among the four Z. mollissima sensu lato (s.l.) clades are similar to those between any of them and Z. dixoni, and exceed that between the two congeneric outgroup species. We lectotypify the name Oreocin- cla rostrata Hodgson, 1845 with the Z. mollissima sensu stricto (s.s.) specimen long considered its type. No available name unambiguously pertains to the Himalayan Forest Thrush. Conclusions: The Plain-backed Thrush Z. mollissima s.l. comprises at least three species: Alpine Thrush Z. mollissima s.s., with a widespread alpine breeding distribution; Sichuan Forest Thrush Z. griseiceps, breeding in central Sichuan forests; and Himalayan Forest Thrush, breeding in the eastern Himalayas and northwest Yunnan (at least), which is described herein as a new species. “Yunnan Thrush” requires further study.
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| 4. |
- Alström, Per, et al.
(författare)
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Multiple species within the Striated Prinia Prinia crinigera-Brown Prinia P. polychroa complex revealed through an integrative taxonomic approach
- 2020
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Ingår i: Ibis. - : Wiley. - 0019-1019 .- 1474-919X. ; 162:3, s. 936-967
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Tidskriftsartikel (refereegranskat)abstract
- We re-evaluated the taxonomy of the Striated Prinia Prinia crinigera-Brown Prinia P. polychroa complex using molecular, morphological and vocal analyses. The extensive seasonal, sexual, age-related, geographical and taxon-specific variation in this complex has never before been adequately studied. As no previous genetic or vocal analyses have focused on this group, misinterpretation of taxonomic signals from limited conventional morphological study alone was likely. Using mitochondrial and nuclear DNA, we found that P. crinigera sensu lato (s.l.) comprises two non-sister groups of taxa (Himalayan crinigera and Chinese striata groups) that differ substantially morphologically and vocally and that are broadly sympatric in Yunnan Province, China. Prinia polychroa cooki (Myanmar) and P. p. rocki (southern Vietnam) are each morphologically, vocally and genetically distinct. Thai, Cambodian and Laotian populations formerly ascribed to P. p. cooki are morphologically and vocally most similar to and most closely related to Javan P. p. polychroa, and require a new name, proposed here. Prinia p. bangsi of Yunnan is part of the crinigera group rather than of P. polychroa, and hence there is no evidence for sympatry between P. polychroa s.l. and P. crinigera s.l., nor of the occurrence of P. polychroa in mainland China or Taiwan. We recommend the recognition of five species in the complex, with the following suggestions for new English names: Himalayan Prinia P. crinigera sensu stricto (s.s.; with subspecies striatula, crinigera, yunnanensis and bangsi); Chinese Prinia P. striata (subspecies catharia, parumstriata and striata); Burmese Prinia P. cooki (monotypic); Annam Prinia P. rocki (monotypic) and Deignan's Prinia P. polychroa s.s. (subspecies Javan polychroa and the new Southeast Asian taxon). This study underlines the importance of using multiple datasets for the elucidation of diversity of cryptic bird species and their evolutionary history and biogeography.
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| 5. |
- Malavelle, Florent F., et al.
(författare)
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Strong constraints on aerosol-cloud interactions from volcanic eruptions
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 546:7659, s. 485-491
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Tidskriftsartikel (refereegranskat)abstract
- Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosol-cloud interactions. Here we show that the massive 2014-2015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud droplets-consistent with expectations-but had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around -0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response.
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