Rainfall trends over a North Atlantic small island in the period 1937/1938–2016/2017 and an early climate teleconnection

2021 ◽  
Vol 144 (1-2) ◽  
pp. 469-491
Author(s):  
Luis Angel Espinosa ◽  
Maria Manuela Portela ◽  
Rui Rodrigues
Keyword(s):  
North Atlantic ◽  
Small Island ◽  
Rainfall Trends

scholarly journals Significant Extremal Dependence of a Daily North Atlantic Oscillation Index (NAOI) and Weighted Regionalised Rainfall in a Small Island Using the Extremogram

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2989
Author(s):  
Luis Angel Espinosa ◽  
Maria Manuela Portela ◽  
Rui Rodrigues
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
North Atlantic Oscillation Index ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Statistical Dependence ◽  
Small Island ◽  
Extremal Dependence ◽  
Rain Gauges

Extremal dependence or independence may occur among the components of univariate or bivariate random vectors. Assessing which asymptotic regime occurs and also its extent are crucial tasks when such vectors are used as statistical models for risk assessment in the field of Climatology under climate change conditions. Motivated by the poor resolution of current global climate models in North Atlantic Small Islands, the extremal dependence between a North Atlantic Oscillation index (NAOI) and rainfall was considered at multi-year dominance of negative and positive NAOI, i.e., −NAOI and +NAOI dominance subperiods, respectively. The datasets used (from 1948–2017) were daily NAOI, and three daily weighted regionalised rainfall series computed based on factor analysis and the Voronoi polygons method from 40 rain gauges in the small island of Madeira (∼740 km2), Portugal. The extremogram technique was applied for measuring the extremal dependence within the NAOI univariate series. The cross-extremogram determined the dependence between the upper tail of the weighted regionalised rainfalls, and the upper and lower tails of daily NAOI. Throughout the 70-year period, the results suggest systematic evidence of statistical dependence over Madeira between exceptionally −NAOI records and extreme rainfalls, which is stronger in the −NAOI dominance subperiods. The extremal dependence for +NAOI records is only significant in recent years, however, with a still unclear +NAOI dominance.

scholarly journals Bivariate Modelling of a Teleconnection Index and Extreme Rainfall in a Small North Atlantic Island

Climate ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 86
Author(s):  
Luis Angel Espinosa ◽  
Maria Manuela Portela ◽  
João Dehon Pontes Filho ◽  
Martina Zelenakova
Keyword(s):  
Climate Variability ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Extreme Rainfall ◽  
Small Island ◽  
Return Periods ◽  
Rainfall Events ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

This paper explores practical applications of bivariate modelling via copulas of two likely dependent random variables, i.e., of the North Atlantic Oscillation (NAO) coupled with extreme rainfall on the small island of Madeira, Portugal. Madeira, due to its small size (∼740 km2), very pronounced mountain landscape, and location in the North Atlantic, experiences a wide range of rainfall regimes, or microclimates, which hamper the analyses of extreme rainfall. Previous studies showed that the influence of the North Atlantic Oscillation (NAO) on extreme rainfall is at its largest in the North Atlantic sector, with the likelihood of increased rainfall events from December through February, particularly during negative NAO phases. Thus, a copula-based approach was adopted for teleconnection, aiming at assigning return periods of daily values of an NAO index (NAOI) coupled with extreme daily rainfalls—for the period from December 1967 to February 2017—at six representative rain gauges of the island. The results show that (i) bivariate copulas describing the dependence characteristics of the underlying joint distributions may provide useful analytical expressions of the return periods of the coupled previous NAOI and extreme rainfall and (ii) that recent years show signs of increasing climate variability with more anomalous daily negative NAOI along with higher extreme rainfall events. These findings highlight the importance of multivariate modelling for teleconnections of prominent patterns of climate variability, such as the NAO, to extreme rainfall in North Atlantic regions, especially in small islands that are highly vulnerable to the effects of abrupt climate variability.

scholarly journals The Norn Hildina Ballad from the Shetland Islands: Scandinavian parallels and attempts at reconstruction/translation

2020 ◽  
Vol 25 (1) ◽  
pp. 61-119
Author(s):  
Mariano González Campo
Keyword(s):  
Nineteenth Century ◽  
North Atlantic ◽  
Small Island ◽  
Comparative Approach ◽  
Old Norse ◽  
Shetland Islands ◽  
Orkney Islands

The Shetland Islands, together with the Orkney Islands, were until the nineteenth century a remarkable reservoir of the so-called Norn language, an extinct insular variety of Old Norse closely related to Icelandic and, specially, Faroese. Norn was preserved in these North-Atlantic British islands in form of single words, proverbs, or prayers. However, the longest and most complete text in Norn is the Shetlandic Hildina Ballad, collected on the small island of Foula in 1774 by George Low and consisting of thirtyfive stanzas. In this article I intend to offer a comparative approach to this Norn oral text refering to its Scandinavian parallels and the attempts at reconstruction and translation carried out by several scholars such as Marius Hægstad, Sophus Bugge, William G. Collinwood, Norah Kershaw, or Eigil Lehmann.

Regional Precipitation Trends: Distinguishing Natural Variability from Anthropogenic Forcing

2010 ◽  
Vol 23 (8) ◽  
pp. 2131-2145 ◽  
Author(s):  
Martin Hoerling ◽  
Jon Eischeid ◽  
Judith Perlwitz
Keyword(s):  
Pacific Ocean ◽  
Greenhouse Gases ◽  
North Atlantic ◽  
Eastern Pacific ◽  
West Pacific ◽  
Aerosol Forcing ◽  
Regional Trends ◽  
Rainfall Trends ◽  
Regional Rainfall ◽  
Precipitation Trends

Abstract In this study, the nature and causes for observed regional precipitation trends during 1977–2006 are diagnosed. It is found that major features of regional trends in annual precipitation during 1977–2006 are consistent with an atmospheric response to observed sea surface temperature (SST) variability. This includes drying over the eastern Pacific Ocean that extends into western portions of the Americas related to a cooling of eastern Pacific SSTs, and broad increases in rainfall over the tropical Eastern Hemisphere, including a Sahelian rainfall recovery and increased wetness over the Indo–West Pacific related to North Atlantic and Indo–West Pacific ocean warming. It is further determined that these relationships between SST and rainfall change are generally not symptomatic of human-induced emissions of greenhouse gases (GHGs) and aerosols. The intensity of regional trends simulated in climate models using observed time variability in greenhouse gases, tropospheric sulfate aerosol, and solar and volcanic aerosol forcing are appreciably weaker than those observed and also weaker than those simulated in atmospheric models using only observed SST forcing. The pattern of rainfall trends occurring in response to such external radiative forcing also departs significantly from observations, especially a simulated increase in rainfall over the tropical Pacific and southeastern Australia that are opposite in sign to the actual drying in these areas. Additional experiments illustrate that the discrepancy between observed and GHG-forced rainfall changes during 1977–2006 results mostly from the differences between observed and externally forced SST trends. Only weak rainfall sensitivity is found to occur in response to the uniform distribution of SST warming that is induced by GHG and aerosol forcing, whereas the particular pattern of the observed SST change that includes an increased SST contrast between the east Pacific and the Indian Ocean, and strong regional warming of the North Atlantic Ocean, was a key driver of regional rainfall trends. The results of this attribution study on the causes for 1977–2006 regional rainfall changes are used to discuss prediction challenges including the likelihood that recent rainfall trends might persist.

Remotely-controlled ice-nucleating particle measurements from the Eastern North Atlantic during autumn and winter

2021 ◽  
Author(s):  
Elise Wilbourn ◽  
Naruki Hiranuma ◽  
Larissa Lacher ◽  
Jens Nadolny ◽  
Ottmar Möhler
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Department Of Energy ◽  
Small Island ◽  
Remote Maintenance ◽  
Atmospheric Radiation Measurement ◽  
Time Of Year ◽  
Eastern North Atlantic ◽  
Heterogeneous Formation

<p>Ice-nucleating particles (INPs) are aerosol particles that catalyze the heterogeneous formation of ice crystals under ice supersaturation conditions. These INPs can change cloud characteristics on wide spatiotemporal scales, including albedo and radiative effects, as well as precipitation types and amounts, thus affecting both weather and climate. However, INP measurements with reasonable temporal resolution have been challenging in terms of both technology and logistics in our research community. Here we present preliminary results of our recent six-month effort from the Eastern North Atlantic (ENA) field campaign to advance the research and explore remote operation of the plug-and-play Portable Ice Nucleation Experiment (PINE) chamber to semi-autonomously measure marine boundary layer INP concentrations. In this campaign we deployed our PINE chamber at the U.S. Department of Energy Atmospheric Radiation Measurement (DOE ARM) ENA site on Graciosa Island, Azores (39° 5′ 29.76″ N, 28° 1′ 32.52″ W). The PINE chamber has been continuously operated since October 2020 with supervision and periodic remote maintenance by scientists in West Texas. The INP measurements were conducted at mixed-phase cloud conditions at temperatures between -14°C and -33°C. These measurements, along with other aerosol particle and meteorological measurements made by a suite of instruments collocated at the DOE ARM site, give unique insights on the response of INP concentrations to local and mesoscale dynamics and thermodynamic processes. This study provides the first remote and continuous INP measurements over two meteorological seasons made in the ENA region within the marine boundary layer, giving insights into an area with prominent marine influences on aerosol populations. Graciosa Island is a small island (only 61 km<sup>2</sup>) surrounded by oligotrophic oceans, and these measurements were made during the most biologically productive time of year for phytoplankton in the surrounding ocean waters. The long-term and continuous nature of these measurements allows a unique comparison of marine biological productivity, using satellite-derived chlorophyll a as a proxy for biomass, and INP concentrations. The median INP concentrations at -25 °C and -30 °C were around 4 INP L<sup>-1</sup> and 27 INP L<sup>-1 </sup>respectively. Our preliminary data suggest that INP concentrations measured by the PINE chamber at the ENA site are comparable to other studies at locations with primarily marine INPs. More details will be offered in our presentation.</p>

The Atmospheric Response to North Atlantic SST Trends, 1870–2019

2020 ◽  
Author(s):  
Kristopher B. Karnauskas ◽  
Lei Zhang ◽  
Dillon J. Amaya
Keyword(s):  
North Atlantic ◽  
Atmospheric Response

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic

Power-feed equipment for the North Atlantic link

1957 ◽  
Vol 104 (4S) ◽  
pp. 51-59
Author(s):  
G.W. Meszaros ◽  
H.H. Spencer
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic
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