Shallow thermal structure and hydrology of Ascension Island, South Atlantic ocean

Geothermics ◽  
1996 ◽  
Vol 25 (4-5) ◽  
pp. 521-541 ◽  
Author(s):  
Dennis L. Nielson ◽  
Michael C. Adams ◽  
Bruce S. Sibbett ◽  
Phillip M. Wright
2018 ◽  
Vol 147 ◽  
pp. 229-235
Author(s):  
Bart Van de Vijver ◽  
Sandra Wilfert ◽  
David M. John ◽  
Horst Lange-Bertalot

Geothermics ◽  
1996 ◽  
Vol 25 (4-5) ◽  
pp. 427-448 ◽  
Author(s):  
Dennis L. Nielson ◽  
Bruce S. Sibbett

2021 ◽  
Author(s):  
Rosmeri da Rocha ◽  
Eduardo de Jesus ◽  
Michelle Reboita ◽  
Natália Crespo ◽  
Luiz Gozzo

<p>Subtropical cyclones (SCs) climatology is evaluated in three simulations of Regional Climate Modeling version 4 (RegCM4) and in its global climate models (GCMs) drivers (HadGEM2-ES, MPI-ESM-MR and GFDL-ESM2M) over the South America domain. Three algorithms are applied to identify the SCs: the first tracks all cyclones, the second computes the thermal structure of the cyclones based on the Cyclone Phase Space (CPS) methodology, and the third automatically selects only the cyclones with subtropical features. After that, two ensembles were performed (RegCM4 and GCMs) and their climatologies are validated through comparisons with ERA-Interim reanalysis for the period 1979-2005. Over the southwestern South Atlantic Ocean, the annual average and standard deviation of SCs are 8.0± 2.5, 7.6± 2.3 and 7.2± 3.0, respectively, in ERA-Interim, RegCM4 and GCMs. Although both ensembles have a good performance in simulating the climatology of SCs, RegCM4 over perform the GCMs showing a better skill in representing both the annual mean and the interannual variability measured by the standard deviation. Moreover, RegCM4 simulates the spatial pattern of the cyclogenesis density closer to ERA-Interim than GCMs, which is another added value of the regional downscaling. SCs represent a small fraction of all cyclones over the region, which is 4.1% in ERA-Interim and GCMs and 3.5% in RegCM4. The relative importance of SCs to the total of cyclones increased to ~40% in the region near the southeast coast of Brazil. In terms of seasonal mean, simulations are able to capture the observed pattern that has the austral summer as the most cyclogenetic season. </p>


Geothermics ◽  
1996 ◽  
Vol 25 (4-5) ◽  
pp. 449-470 ◽  
Author(s):  
Barry Weaver ◽  
Aditya Kar ◽  
Jon Davidson ◽  
Mike Colucci

Phytotaxa ◽  
2017 ◽  
Vol 331 (1) ◽  
pp. 65 ◽  
Author(s):  
ALAN GRAY ◽  
GAIL STOTT

Material from the Cyperus appendiculatus group was collected from Ascension Island and compared using a common garden study and to herbarium specimens from throughout the geographical range. Cyperus stroudii is described as a new species, known only from Ascension Island in the South Atlantic Ocean, it closest relative is C. appendiculatus also native to Ascension Island and Brazil. Cyperus stroudii differs from C. appendiculatus in its dwarf habit and other morphological characteristics, and these characteristics are retained under common environmental conditions indicative of genomic differences.


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