scholarly journals Supplementary material to "Mechanisms of the Sea–Air CO<sub>2</sub> Flux Seasonal Cycle biases in CMIP5 Earth Systems Models in the Southern Ocean"

2017 ◽  
Author(s):  
N. Precious Mongwe ◽  
Marcello Vichi ◽  
Pedro M. S. Monteiro
Keyword(s):  
Southern Ocean ◽  
Seasonal Cycle ◽  
Earth Systems ◽  
Supplementary Material ◽  
Systems Models

scholarly journals The Seasonal Cycle of Blocking and Associated Physical Mechanisms in the Australian Region and Relationship with Rainfall

2013 ◽  
Vol 141 (12) ◽  
pp. 4534-4553 ◽  
Author(s):  
M. J. Pook ◽  
J. S. Risbey ◽  
P. C. McIntosh ◽  
C. C. Ummenhofer ◽  
A. G. Marshall ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Seasonal Cycle ◽  
Seasonal Temperature ◽  
Ocean Fronts ◽  
Temperature Changes ◽  
Physical Mechanisms ◽  
Australian Region ◽  
Continental Antarctica ◽  
Positive Correlations ◽  
Blocking Index

Abstract The seasonal cycle of blocking in the Australian region is shown to be associated with major seasonal temperature changes over continental Antarctica (approximately 15°–35°C) and Australia (about 8°–17°C) and with minor changes over the surrounding oceans (below 5°C). These changes are superimposed on a favorable background state for blocking in the region resulting from a conjunction of physical influences. These include the geographical configuration and topography of the Australian and Antarctic continents and the positive west to east gradient of sea surface temperature in the Indo-Australian sector of the Southern Ocean. Blocking is represented by a blocking index (BI) developed by the Australian Bureau of Meteorology. The BI has a marked seasonal cycle that reflects seasonal changes in the strength of the westerly winds in the midtroposphere at selected latitudes. Significant correlations between the BI at Australian longitudes and rainfall have been demonstrated in southern and central Australia for the austral autumn, winter, and spring. Patchy positive correlations are evident in the south during summer but significant negative correlations are apparent in the central tropical north. By decomposing the rainfall into its contributions from identifiable synoptic types during the April–October growing season, it is shown that the high correlation between blocking and rainfall in southern Australia is explained by the component of rainfall associated with cutoff lows. These systems form the cyclonic components of blocking dipoles. In contrast, there is no significant correlation between the BI and rainfall from Southern Ocean fronts.

scholarly journals Sixty years of radiocarbon dioxide measurements at Wellington, New Zealand 1954–2014

2016 ◽  
Author(s):  
Jocelyn C. Turnbull ◽  
Sara E. Mikaloff Fletcher ◽  
India Ansell ◽  
Gordon Brailsford ◽  
Rowena Moss ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Ocean ◽  
Co2 Emissions ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Seasonal Cycle ◽  
Fossil Fuel ◽  
Anthropogenic Sources ◽  
Deep Waters ◽  
Cape Grim

Abstract. We present 60 years of Δ14CO2 measurements from Wellington, New Zealand (41° S, 175° E). The record has been extended and fully revised. New measurements have been used to evaluate the existing record and to replace original measurements where warranted. This is the earliest atmospheric Δ14CO2 record and records the rise of the 14C "bomb spike", the subsequent decline in Δ14CO2 as bomb 14C moved throughout the carbon cycle and increasing fossil fuel CO2 emissions further decreased atmospheric Δ14CO2. The initially large seasonal cycle in the 1960s reduces in amplitude and eventually reverses in phase, resulting in a small seasonal cycle of about 2 ‰ in the 2000s. The seasonal cycle at Wellington is dominated by the seasonality of cross-tropopause transport, and differs slightly from that at Cape Grim, Australia, which is influenced by anthropogenic sources in winter. Δ14CO2 at Cape Grim and Wellington show very similar trends, with significant differences only during periods of known measurement uncertainty. In contrast, Northern Hemisphere clean air sites show a higher and earlier bomb 14C peak, consistent with a 1.4-year interhemispheric exchange time. From the 1970s until the early 2000s, the Northern and Southern Hemisphere Δ14CO2 were quite similar, apparently due to the balance of 14C-free fossil fuel CO2 emissions in the north and 14C-depleted ocean upwelling in the south. The Southern Hemisphere sites show a consistent and marked elevation above the Northern Hemisphere sites since the early 2000s, which is most likely due to reduced upwelling of 14C-depleted and carbon-rich deep waters in the Southern Ocean. This developing Δ14CO2 interhemispheric gradient is consistent with recent studies that indicate a reinvigorated Southern Ocean carbon sink since the mid-2000s, and suggests that upwelling of deep waters plays an important role in this change.

scholarly journals Supplementary material to "Changes of Anthropogenic Precursor Emissions Drive Shifts of Ozone Seasonal Cycle throughout Northern Midlatitude Troposphere"

2021 ◽  
Author(s):  
Henry Bowman ◽  
Steven Turnock ◽  
Susanne E. Bauer ◽  
Kostas Tsigaridis ◽  
Makoto Deushi ◽  
...  
Keyword(s):  
Seasonal Cycle ◽  
Supplementary Material

The Southern Ocean carbon sink 1985-2018: first results of the RECCAP2 project

2021 ◽  
Author(s):  
Judith Hauck ◽  
Luke Gregor ◽  
Cara Nissen ◽  
Eric Mortenson ◽  
Seth Bushinsky ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Seasonal Cycle ◽  
Carbon Sink ◽  
Global Ocean ◽  
Biogeochemical Models ◽  
Wide Range ◽  
Data Products ◽  
First Results ◽  
Ocean Carbon ◽  
Indian Sector

&lt;p&gt;The Southern Ocean is the main gateway for anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; into the ocean owing to the upwelling of old water masses with low anthropogenic CO&lt;sub&gt;2&lt;/sub&gt; concentration, and the transport of the newly equilibrated surface waters into the ocean interior through intermediate, deep and bottom water formation. Here we present first results of the Southern Ocean chapter of RECCAP2, which is the Global Carbon Project&amp;#8217;s second systematic study on Regional Carbon Cycle Assessment and Processes. In the Southern Ocean chapter, we aim to assess the Southern Ocean carbon sink 1985-2018 from a wide range of available models and data sets, and to identify patterns of regional and temporal variability, model limitations and future challenges.&lt;/p&gt;&lt;p&gt;We gathered global and regional estimates of the air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux over the period 1985-2018 from global ocean biogeochemical models, surface pCO&lt;sub&gt;2&lt;/sub&gt;-based data products, and data-assimilated models. The analysis on the Southern Ocean quantified geographical patterns in the annual mean and seasonal amplitude of air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux, with results presented here aggregated to the level of large-scale ocean biomes.&lt;/p&gt;&lt;p&gt;Considering the suite of observed and modelled estimates, we found that the subtropical seasonally stratified (STSS) biome stands out with the largest air-sea CO&lt;sub&gt;2&lt;/sub&gt; flux per area and a seasonal cycle with largest ocean uptake of CO&lt;sub&gt;2&lt;/sub&gt; in winter, whereas the ice (ICE) biome is characterized by a large ensemble spread and a pronounced seasonal cycle with the largest ocean uptake of CO&lt;sub&gt;2&lt;/sub&gt; in summer. Connecting these two, the subpolar seasonally stratified (SPSS) biome has intermediate flux densities (flux per area), and most models have difficulties simulating the seasonal cycle with strongest uptake during the summer months.&lt;/p&gt;&lt;p&gt;Our analysis also reveals distinct differences between the Atlantic, Pacific and Indian sectors of the aforementioned biomes. In the STSS, the Indian sector contributes most to the ocean carbon sink, followed by the Atlantic and then Pacific sectors. This hierarchy is less pronounced in the models than in the data-products. In the SPSS, only the Atlantic sector exhibits net CO&lt;sub&gt;2&lt;/sub&gt; uptake in all years, likely linked to strong biological production. In the ICE biome, the Atlantic and Pacific sectors take up more CO&lt;sub&gt;2&lt;/sub&gt; than the Indian sector, suggesting a potential role of the Weddell and Ross Gyres.&lt;/p&gt;&lt;p&gt;These first results confirm the global relevance of the Southern Ocean carbon sink and highlight the strong regional and interannual variability of the Southern Ocean carbon uptake in connection to physical and biogeochemical processes.&lt;/p&gt;

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