A new high northern latitude dinocyst-based magneto-biostratigraphic calibration for the Norwegian-Greenland Sea

2019 ◽  
Vol 52 (4) ◽  
pp. 435-460 ◽  
Author(s):  
James S. Eldrett ◽  
Ian C. Harding ◽  
Rob Wilshaw ◽  
Chuang Xuan
2014 ◽  
Vol 60 (2) ◽  
pp. 155-158 ◽  
Author(s):  
Siiri Kõljalg ◽  
Kaidi Telling ◽  
Kristi Huik ◽  
Marko Murruste ◽  
Virve Saarevet ◽  
...  

2015 ◽  
Vol 15 (5) ◽  
pp. 7089-7139 ◽  
Author(s):  
J. M. Barlow ◽  
P. I. Palmer ◽  
L. M. Bruhwiler ◽  
P. Tans

Abstract. Atmospheric variations of carbon dioxide (CO2) mole fraction reflect changes in atmospheric transport and regional patterns of surface emission and uptake. We report new estimates for changes in the phase and amplitude of observed high northern latitude CO2 seasonal variations, indicative of biospheric changes, by spectrally decomposing multi-decadal records of surface CO2 mole fraction using a wavelet transform to isolate the changes in the observed seasonal cycle. We also perform similar analysis of the first time derivative of CO2 mole fraction, ΔtCO2, that is a crude proxy for changes in CO2 flux. Using numerical experiments, we quantify the aliasing error associated with independently identifying trends in phase and peak uptake and release to be 10–25%, with the smallest biases in phase associated with the analysis of ΔtCO2. We report our analysis from Barrow, Alaska (BRW) during 1973–2013, which is representative of the broader Arctic region. We determine an amplitude trend of 0.09 ± 0.02 ppm yr−1, which is consistent with previous work. Using ΔtCO2 we determine estimates for the timing of the onset of net uptake and release of CO2 of −0.14 ± 0.14 and −0.25 ± 0.08 days yr−1, respectively, and a corresponding uptake period of −0.11 ± 0.16 days yr−1, which are significantly different to previously reported estimates. We find that the wavelet transform method has significant skill in characterizing changes in the peak uptake and release. We find a trend of 0.65 ± 0.34% (p< 0.01) and 0.42 ± 0.34% (p<0.05) for rates of peak uptake and release, respectively. Our analysis does not provide direct evidence about the balance between uptake and release of carbon, but changes in the peak uptake and release together with an invariant growing period length provides indirect evidence that high northern latitude ecosystems are progressively taking up more carbon.


2016 ◽  
Author(s):  
Nicola J. Warwick ◽  
Michelle L. Cain ◽  
Rebecca Fisher ◽  
James L. France ◽  
David Lowry ◽  
...  

Abstract. We present a global methane modelling study assessing the sensitivity of Arctic atmospheric CH4 mole fractions, δ13C-CH4 and δD-CH4 to uncertainties in Arctic methane sources. Model simulations include methane tracers coloured by source and isotopic composition and are compared with atmospheric data at four high northern latitude measurement sites. We find the model's ability to capture the magnitude and phase of observed seasonal cycles of CH4 mixing ratios, δ13C-CH4 and δD-CH4 in high northern latitudes is much improved using a later spring kick-off and autumn decline in high northern latitude wetland emissions than predicted by most process models. Results from our model simulations indicate that recent predictions of large methane emissions from thawing submarine permafrost in the East Siberian Arctic Shelf region could only be reconciled with global scale atmospheric observations by making large adjustments to high latitude emission inventories.


2016 ◽  
Vol 60 (9) ◽  
pp. 1289-1296 ◽  
Author(s):  
R. B. Kvaran ◽  
M. I. Sigurdsson ◽  
S. J. Skarphedinsdottir ◽  
G. H. Sigurdsson

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