scholarly journals Quantifying the mass loading of particles in an ash cloud remobilised from tephra deposits on Iceland

2016 ◽  
Author(s):  
Frances Beckett ◽  
Arve Kylling ◽  
Guðmunda Sigurðardóttir ◽  
Sibylle von Löwis ◽  
Claire Witham
Keyword(s):  
North Atlantic ◽  
Volcanic Ash ◽  
North Atlantic Ocean ◽  
Temperature Inversion ◽  
Mass Loading ◽  
Satellite Measurements ◽  
The North ◽  
Tephra Deposits ◽  
Strong Surface ◽  
Ash Cloud

Abstract. On the 16–17 September 2013 strong surface winds over tephra deposits in southern Iceland led to the resuspension and subsequent advection of significant quantities of volcanic ash. The resulting resuspended ash cloud was transported to the south-east over the North Atlantic Ocean and, due to clear skies at the time, was exceptionally well observed in satellite imagery. We use satellite based measurements in combination with radiative transfer and dispersion modelling to quantify the total mass of ash resuspended during this event. Typically ash clouds from explosive eruptions are identified in satellite measurements from a negative Brightness Temperature Difference (BTD) signal, however this technique assumes that the ash resides at high levels in the atmosphere. Due to a temperature inversion in the troposphere over southern Iceland during the 16 September 2013 the resuspended ash cloud was constrained to altitudes of

scholarly journals Quantifying the mass loading of particles in an ash cloud remobilized from tephra deposits on Iceland

2017 ◽  
Vol 17 (7) ◽  
pp. 4401-4418 ◽  
Author(s):  
Frances Beckett ◽  
Arve Kylling ◽  
Guðmunda Sigurðardóttir ◽  
Sibylle von Löwis ◽  
Claire Witham
Keyword(s):  
Infrared Imaging ◽  
North Atlantic Ocean ◽  
Dispersion Model ◽  
Source Area ◽  
Optimal Estimation ◽  
Temperature Inversion ◽  
Dispersion Modelling ◽  
Satellite Measurements ◽  
Tephra Deposits ◽  
Ash Cloud

Abstract. On 16–17 September 2013 strong surface winds over tephra deposits in southern Iceland led to the resuspension and subsequent advection of significant quantities of volcanic ash. The resulting resuspended ash cloud was transported to the south-east over the North Atlantic Ocean and, due to clear skies at the time, was exceptionally well observed in satellite imagery. We use satellite-based measurements in combination with radiative transfer and dispersion modelling to quantify the total mass of ash resuspended during this event. Typically ash clouds from explosive eruptions are identified in satellite measurements from a negative brightness temperature difference (BTD) signal; however this technique assumes that the ash resides at high levels in the atmosphere. Due to a temperature inversion in the troposphere over southern Iceland during 16 September 2013, the resuspended ash cloud was constrained to altitudes of  <  2 km a.s.l. We show that a positive BTD signal can instead be used to identify ash-containing pixels from satellite measurements. The timing and location of the ash cloud identified using this technique from measurements made by the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (NPP) satellite agree well with model predictions using the dispersion model NAME (Numerical Atmospheric-dispersion Modelling Environment). Total column mass loadings are determined from the VIIRS data using an optimal estimation technique which accounts for the low altitude of the resuspended ash cloud and are used to calibrate the emission rate in the resuspended ash scheme in NAME. Considering the tephra deposits from the recent eruptions of Eyjafjallajökull and Grímsvötn as the potential source area for resuspension for this event, we estimate that  ∼  0.2 Tg of ash was remobilized during 16–17 September 2013.

Zooplankton Biogeochemical Cycles

2017 ◽  
Author(s):  
Deborah Steinberg
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Significant Proportion ◽  
Biogeochemical Cycles ◽  
Biological Pump ◽  
The North ◽  
Particle Export ◽  
Chemical Cycling ◽  
Cycling Of Nutrients ◽  
Planktonic Communities

The structure of planktonic communities profoundly affects particle export and sequestration of organic material (the biological pump) and the chemical cycling of nutrients. This chapter describes the integral and multifaceted role zooplankton (both protozoan and metazoan) play in the export and cycling of elements in the ocean, with an emphasis on the North Atlantic Ocean and adjacent seas. Zooplankton consume a significant proportion of primary production across the world's oceans, and their metabolism plays a key role in recycling carbon, nitrogen, and other elements. The chapter also addresses how human or climate-influenced changes in North Atlantic zooplankton populations may in turn drive changes in zooplankton-mediated biogeochemical cycling.

Spatiotemporal evolution of the chlorophyll a trend in the North Atlantic Ocean

2018 ◽  
Vol 612 ◽  
pp. 1141-1148 ◽  
Author(s):  
Min Zhang ◽  
Yuanling Zhang ◽  
Qi Shu ◽  
Chang Zhao ◽  
Gang Wang ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Chlorophyll A ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Spatiotemporal Evolution ◽  
The North ◽  
The North Atlantic

On the uncertainty of future projections of Marine Heatwave events in the North Atlantic Ocean

2021 ◽  
Vol 56 (7-8) ◽  
pp. 2027-2056
Author(s):  
Sandra M. Plecha ◽  
Pedro M. M. Soares ◽  
Susana M. Silva-Fernandes ◽  
William Cabos
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Future Projections ◽  
The North ◽  
The North Atlantic

Monthly satellite-derived phytoplankton pigment distribution for the North Atlantic Ocean basin

Eos ◽  
1986 ◽  
Vol 67 (44) ◽  
pp. 835 ◽  
Author(s):  
W. E. Esaias ◽  
G. C. Feldman ◽  
C. R. McClain ◽  
J. A. Elrod
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Ocean Basin ◽  
Phytoplankton Pigment ◽  
The North ◽  
Pigment Distribution ◽  
The North Atlantic

scholarly journals A New Method for Tracking Meddies by Satellite Altimetry

2014 ◽  
Vol 31 (6) ◽  
pp. 1434-1445 ◽  
Author(s):  
Federico Ienna ◽  
Young-Heon Jo ◽  
Xiao-Hai Yan
Keyword(s):  
Remote Sensing ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Saline Water ◽  
Ensemble Empirical Mode Decomposition ◽  
Altimeter Data ◽  
In Situ Techniques ◽  
The North ◽  
The North Atlantic

Abstract Subsurface coherent vortices in the North Atlantic, whose saline water originates from the Mediterranean Sea and which are known as Mediterranean eddies (meddies), have been of particular interest to physical oceanographers since their discovery, especially for their salt and heat transport properties into the North Atlantic Ocean. Many studies in the past have been successful in observing and studying the typical properties of meddies by probing them with in situ techniques. The use of remote sensing techniques would offer a much cheaper and easier alternative for studying these phenomena, but only a few past studies have been able to study meddies by remote sensing, and a reliable method for observing them remotely remains elusive. This research presents a new way of locating and tracking meddies in the North Atlantic Ocean using satellite altimeter data. The method presented in this research makes use of ensemble empirical mode decomposition (EEMD) as a means to isolate the surface expressions of meddies on the ocean surface and separates them from any other surface constituents, allowing robust meddies to be consistently tracked by satellite. One such meddy is successfully tracked over a 6-month time period (2 November 2005 to 17 May 2006). Results of the satellite tracking method are verified using expendable bathythermographs (XBT).

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