Synthesis of integrated primary production in the Arctic Ocean: II. In situ and remotely sensed estimates

Abstract The authors examine five recent reanalysis products [NCEP Climate Forecast System Reanalysis (CFSR), Modern-Era Retrospective Analysis for Research and Applications (MERRA), Japanese 25-year Reanalysis Project (JRA-25), Interim ECMWF Re-Analysis (ERA-Interim), and Arctic System Reanalysis (ASR)] for 1) trends in near-surface radiation fluxes, air temperature, and humidity, which are important indicators of changes within the Arctic Ocean and also influence sea ice and ocean conditions, and 2) fidelity of these atmospheric fields and effects for an extreme event: namely, the 2007 ice retreat. An analysis of trends over the Arctic for the past decade (2000–09) shows that reanalysis solutions have large spreads, particularly for downwelling shortwave radiation. In many cases, the differences in significant trends between the five reanalysis products are comparable to the estimated trend within a particular product. These discrepancies make it difficult to establish a consensus on likely changes occurring in the Arctic solely based on results from reanalyses fields. Regarding the 2007 ice retreat event, comparisons with remotely sensed estimates of downwelling radiation observations against these reanalysis products present an ambiguity. Remotely sensed observations from a study cited herewith suggest a large increase in downwelling summertime shortwave radiation and decrease in downwelling summertime longwave radiation from 2006 and 2007. On the contrary, the reanalysis products show only small gains in summertime shortwave radiation, if any; however, all the products show increases in downwelling longwave radiation. Thus, agreement within reanalysis fields needs to be further checked against observations to assess possible biases common to all products.

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Regional variability of acidification in the Arctic: a sea of contrasts

Biogeosciences ◽

10.5194/bg-11-293-2014 ◽

2014 ◽

Vol 11 (2) ◽

pp. 293-308 ◽

Cited By ~ 23

Author(s):

E. E. Popova ◽

A. Yool ◽

Y. Aksenov ◽

A. C. Coward ◽

T. R. Anderson

Keyword(s):

Climate Change ◽

Primary Production ◽

Arctic Ocean ◽

Canadian Arctic ◽

Atmospheric Co2 ◽

The Arctic ◽

Canadian Arctic Archipelago ◽

Regional Variability ◽

The Arctic Ocean ◽

The Impact

Abstract. The Arctic Ocean is a region that is particularly vulnerable to the impact of ocean acidification driven by rising atmospheric CO2, with potentially negative consequences for calcifying organisms such as coccolithophorids and foraminiferans. In this study, we use an ocean-only general circulation model, with embedded biogeochemistry and a comprehensive description of the ocean carbon cycle, to study the response of pH and saturation states of calcite and aragonite to rising atmospheric pCO2 and changing climate in the Arctic Ocean. Particular attention is paid to the strong regional variability within the Arctic, and, for comparison, simulation results are contrasted with those for the global ocean. Simulations were run to year 2099 using the RCP8.5 (an Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) scenario with the highest concentrations of atmospheric CO2). The separate impacts of the direct increase in atmospheric CO2 and indirect effects via impact of climate change (changing temperature, stratification, primary production and freshwater fluxes) were examined by undertaking two simulations, one with the full system and the other in which atmospheric CO2 was prevented from increasing beyond its preindustrial level (year 1860). Results indicate that the impact of climate change, and spatial heterogeneity thereof, plays a strong role in the declines in pH and carbonate saturation (Ω) seen in the Arctic. The central Arctic, Canadian Arctic Archipelago and Baffin Bay show greatest rates of acidification and Ω decline as a result of melting sea ice. In contrast, areas affected by Atlantic inflow including the Greenland Sea and outer shelves of the Barents, Kara and Laptev seas, had minimal decreases in pH and Ω because diminishing ice cover led to greater vertical mixing and primary production. As a consequence, the projected onset of undersaturation in respect to aragonite is highly variable regionally within the Arctic, occurring during the decade of 2000–2010 in the Siberian shelves and Canadian Arctic Archipelago, but as late as the 2080s in the Barents and Norwegian seas. We conclude that, for future projections of acidification and carbonate saturation state in the Arctic, regional variability is significant and needs to be adequately resolved, with particular emphasis on reliable projections of the rates of retreat of the sea ice, which are a major source of uncertainty.

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Assessment of Temperature and Specific Humidity Inversions and Their Relationships in Three Global Reanalysis Products over the Arctic Ocean

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0079.1 ◽

2021 ◽

Vol 60 (4) ◽

pp. 493-511

Author(s):

Liang Chang ◽

Shiqiang Wen ◽

Guoping Gao ◽

Zhen Han ◽

Guiping Feng ◽

...

Keyword(s):

Arctic Ocean ◽

Specific Humidity ◽

The Arctic ◽

Weather Forecasts ◽

The Arctic Ocean ◽

Temperature Inversions ◽

Global Reanalysis ◽

Less Common Multiple ◽

Better Than

AbstractCharacteristics of temperature inversions (TIs) and specific humidity inversions (SHIs) and their relationships in three of the latest global reanalyses—the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-I), the Japanese 55-year Reanalysis (JRA-55), and the ERA5—are assessed against in situ radiosonde (RS) measurements from two expeditions over the Arctic Ocean. All reanalyses tend to detect many fewer TI and SHI occurrences, together with much less common multiple TIs and SHIs per profile than are seen in the RS data in summer 2008, winter 2015, and spring 2015. The reanalyses generally depict well the relationships among TI characteristics seen in RS data, except for the TIs below 400 m in summer, as well as above 1000 m in summer and winter. The depth is simulated worst by the reanalyses among the SHI characteristics, which may result from its sensitivity to the uncertainties in specific humidity in the reanalyses. The strongest TI per profile in RS data exhibits more robust dependency on surface conditions than the strongest SHI per profile, and the former is better presented by the reanalyses than the latter. Furthermore, all reanalyses have difficulties simulating the relationships between TIs and SHIs, together with the correlations between the simultaneous inversions. The accuracy and vertical resolution in the reanalyses are both important to properly capture occurrence and characteristics of the Arctic inversions. In general, ERA5 performs better than ERA-I and JRA-55 in depicting the relationships among the TIs. However, the representation of SHIs is more challenging than TIs in all reanalyses over the Arctic Ocean.

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Changes in phytoplankton concentration now drive increased Arctic Ocean primary production

Science ◽

10.1126/science.aay8380 ◽

2020 ◽

Vol 369 (6500) ◽

pp. 198-202 ◽

Cited By ~ 18

Author(s):

K. M. Lewis ◽

G. L. van Dijken ◽

K. R. Arrigo

Keyword(s):

Sea Ice ◽

Primary Production ◽

Arctic Ocean ◽

Open Water ◽

Water Area ◽

The Arctic ◽

Carbon Export ◽

Phytoplankton Primary Production ◽

Open Water Area ◽

The Arctic Ocean

Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.

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Nitrogen Fixation in a Changing Arctic Ocean: An Overlooked Source of Nitrogen?

Frontiers in Microbiology ◽

10.3389/fmicb.2020.596426 ◽

2020 ◽

Vol 11 ◽

Author(s):

Lisa W. von Friesen ◽

Lasse Riemann

Keyword(s):

Climate Change ◽

Nitrogen Fixation ◽

Primary Production ◽

Arctic Ocean ◽

Current Knowledge ◽

Carbon Sink ◽

Spatial Scales ◽

The Arctic ◽

Future Research ◽

The Arctic Ocean

The Arctic Ocean is the smallest ocean on Earth, yet estimated to play a substantial role as a global carbon sink. As climate change is rapidly changing fundamental components of the Arctic, it is of local and global importance to understand and predict consequences for its carbon dynamics. Primary production in the Arctic Ocean is often nitrogen-limited, and this is predicted to increase in some regions. It is therefore of critical interest that biological nitrogen fixation, a process where some bacteria and archaea termed diazotrophs convert nitrogen gas to bioavailable ammonia, has now been detected in the Arctic Ocean. Several studies report diverse and active diazotrophs on various temporal and spatial scales across the Arctic Ocean. Their ecology and biogeochemical impact remain poorly known, and nitrogen fixation is so far absent from models of primary production in the Arctic Ocean. The composition of the diazotroph community appears distinct from other oceans – challenging paradigms of function and regulation of nitrogen fixation. There is evidence of both symbiotic cyanobacterial nitrogen fixation and heterotrophic diazotrophy, but large regions are not yet sampled, and the sparse quantitative data hamper conclusive insights. Hence, it remains to be determined to what extent nitrogen fixation represents a hitherto overlooked source of new nitrogen to consider when predicting future productivity of the Arctic Ocean. Here, we discuss current knowledge on diazotroph distribution, composition, and activity in pelagic and sea ice-associated environments of the Arctic Ocean. Based on this, we identify gaps and outline pertinent research questions in the context of a climate change-influenced Arctic Ocean – with the aim of guiding and encouraging future research on nitrogen fixation in this region.

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Using ship-borne observations of methane isotopic ratio in the Arctic Ocean to understand methane sources in the Arctic

10.5194/acp-2019-595 ◽

2019 ◽

Author(s):

Antoine Berchet ◽

Isabelle Pison ◽

Patrick M. Crill ◽

Brett Thornton ◽

Philippe Bousquet ◽

...

Keyword(s):

Arctic Ocean ◽

Large Scale ◽

Transport Model ◽

Isotopic Ratio ◽

The Arctic ◽

Isotopic Ratios ◽

Air Masses ◽

Remote Areas ◽

The Arctic Ocean

Abstract. Due to the large variety and heterogeneity of sources in remote areas hard to document, the Arctic regional methane budget remain very uncertain. In situ campaigns provide valuable data sets to reduce these uncertainties. Here we analyse data from the SWERUS-C3 campaign, on-board the icebreaker Oden, that took place during summer 2014 in the Arctic Ocean along the Northern Siberian and Alaskan shores. Total concentrations of methane, as well as isotopic ratios were measured continuously during this campaign for 35 days in July and August 2014. Using a chemistry-transport model, we link observed concentrations and isotopic ratios to regional emissions and hemispheric transport structures. A simple inversion system helped constraining source signatures from wetlands in Siberia and Alaska and oceanic sources, as well as the isotopic composition of lower stratosphere air masses. The variation in the signature of low stratosphere air masses, due to strongly fractionating chemical reactions in the stratosphere, was suggested to explain a large share of the observed variability in isotopic ratios. These points at required efforts to better simulate large scale transport and chemistry patterns to use isotopic data in remote areas. It is found that constant and homogeneous source signatures for each type of emission in the region (mostly wetlands and oil and gas industry) is not compatible with the strong synoptic isotopic signal observed in the Arctic. A regional gradient in source signatures is highlighted between Siberian and Alaskan wetlands, the later ones having a lighter signatures than the first ones. Arctic continental shelf sources are suggested to be a mixture of methane from a dominant thermogenic origin and a secondary biogenic one, consistent with previous in-situ isotopic analysis of seepage along the Siberian shores.

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Primary production in Dumbell Bay in the Arctic Ocean

Marine Biology ◽

10.1007/bf00410340 ◽

1980 ◽

Vol 61 (1) ◽

pp. 41-51 ◽

Cited By ~ 15

Author(s):

S. Apollonio

Keyword(s):

Primary Production ◽

Arctic Ocean ◽

The Arctic ◽

The Arctic Ocean

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INTAROS synthesis of gap analysis of the existing Arctic observing systems

10.5194/egusphere-egu2020-20091 ◽

2020 ◽

Author(s):

Roberta Pirazzini ◽

Michael Tjernström ◽

Stein Sandven ◽

Hanne Sagen ◽

Torill Hamre ◽

...

Keyword(s):

Arctic Ocean ◽

Gap Analysis ◽

Satellite Observations ◽

The Arctic ◽

Reference Level ◽

Data Handling ◽

Network Concept ◽

The Arctic Ocean ◽

Observing Systems

A comprehensive assessment of a substantial subset of Arctic observing systems, data collections and satellite products across scientific disciplines was carried out in INTAROS, also including data repositories and a brief scientific gap analysis. The assessments cover a multitude of aspects such as sustainability, technical maturity and data handling for the entire chain from observation to users, including metadata procedures and availability to data. Community based environment monitoring programs were surveyed and assessed separately; they do not form part of the present assessment.The assessed observing systems were first ranked according to general sustainability and other aspects, were analyzed subsequently. While the range of sustainability is large, it was found that high scores on all other aspects, such as for data handling and technical maturity, are more likely for systems with high sustainability. Moreover, many systems with high sustainability, as well as advanced systems for data handling and availability in place, resulted from national commitments to international monitoring or infrastructure programs, several of which are not necessarily particular to the Arctic.Traditionally, terrestrial and atmospheric observation network assessments build on the network concept with a &#8220;comprehensive&#8221; level including all observations, a &#8220;baseline&#8221; level of an agreed subset of sustained observations, and a &#8220;reference&#8221; level, with observations adhering to specific calibrations and traceability criteria. Examples from atmospheric observations are the &#8220;comprehensive&#8221; global GCOS radiosounding network, the &#8220;baseline&#8221; GUAN (GCOS Upper Air Network) and &#8220;reference&#8221; GRUAN (GCOS Reference Upper Air Network) networks. With the lack of in-situ observations especially from the Arctic Ocean and the logistical difficulties to deploy new stations, it was concluded that this concept does not work well in the Arctic.In summary, we recommend that:<ul><li>advancement in Arctic observing should be done in international global or regional programs with well-established routines and procedures, rather than to invest in new Arctic-specific programs</li> <li>investments in new instruments and techniques be done at already established sites, to benefit interdisciplinary studies and optimize infrastructure costs</li> <li>more observations be based on ships of opportunity and that a subset of ocean, sea-ice and atmosphere observations always be made on all research expeditions, regardless of their scientific aim</li> <li>the funding structures for science expeditions is reviewed to maintain, and preferably increase, the number of expeditions and to safeguard funding for appropriate data handling and storage</li> <li>observing-network concept for the atmosphere over the Arctic Ocean is revised, so that coupled reanalyses represent the &#8220;comprehensive level&#8221;, satellite observations complemented with available in-situ data is the &#8220;baseline level&#8221;, while scientific expeditions is the &#8220;reference level&#8221;. This requires substantial improvements in reanalysis, better numerical models and data assimilation, better satellite observations and improved data handling and accessibility for scientific expeditions.</li> </ul>

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