The Iceland Greenland Seas Project

Renfrew, Ian A.; Pickart, Robert S.; Våge, Kjetil; Moore, G. W. K.; Bracegirdle, Thomas J.; Elvidge, Andrew D.; Jeansson, Emil; Lachlan-Cope, Tom; McRaven, Leah; Papritz, Lukas; Reuder, Joachim; Sodemann, Harald; Terpstra, Annick; Waterman, Stephanie; Valdimarsson, Héðinn; Weiss, Alexandra; Almansi, Mattia; Bahr, Frank; Brakstad, Ailin; Barrell, Chris; Brooke, Jennifer; Brooks, Barbara; Brooks, Ian M.; Brooks, M. E.; Bruvik, Erik Magnus; Duscha, Christiane; Fer, Ilker; Golid, Heidi Midtgarden; Hallerstig, Matilda; Hessevik, Idar; Huang, Jin‐ding; Houghton, Leah A.; Jónsson, Steingrímur; Jonassen, Marius O.; Jackson, Karen Roberts; Kvalsund, Karsten; Kolstad, Erik W.; Konstali, Kjersti; Kristiansen, Jørn; Ladkin, R.; Lin, Peigen; Macrander, Annecke; Mitchell, A.; Ólafsson, Haraldur; Pacini, Astrid; Payne, Chris; Pálmason, Bolli; Pérez‐Hernández, M. Dolores; Peterson, Algot Kristoffer; Petersen, Guðrún Nína; Pisareva, Maria N.; Pope, James O.; Seidl, Andrew; Semper, Stefanie; Sergeev, Denis E.; Skjelsvik, Silje; Søiland, Henrik; Smith, D.; Spall, Michael A.; Spengler, Thomas; Touzeau, Alexandra; Tupper, George H.; Weng, Ying; Williams, K. D.; Yang, Xiangwei; Zhou, Shenjie

doi:10.1175/bams-d-18-0217.1

Cited by 27 publications

(59 citation statements)

References 63 publications

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“…As we are interested in the processes shaping the SWI variability in the MBL, the formulation by Pfahl and Wernli (2009) is more adequate to use here as the SWI variability in the measurements and simulations agrees well. To better understand the difference in SWIs between measurements and COSMO iso simulations, further studies are needed such as the detailed analysis of case studies based on extensive 3D-data sets as, for example, collected during the Iceland Greenland Seas Project (Renfrew et al, 2019). Even though near-surface simulated and measured isotope signals do not agree everywhere, the COSMO iso simulations capture the observed variability of the isotopic composition and provide similar distributions of isotope variables as the observations for the three advection categories.…”

Section: B) Cosmo Iso Simulationsmentioning

confidence: 99%

The role of air–sea fluxes for the water vapour isotope signals in the cold and warm sectors of extratropical cyclones over the Southern Ocean

Thurnherr¹,

Hartmuth²,

Jansing³

et al. 2020

Preprint

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Abstract. Meridional atmospheric transport is an important process in the climate system and has implications for the availability of heat and moisture at high latitudes. Near-surface advection of cold and warm temperature over the ocean in the context of extratropical cyclones additionally leads to important air–sea exchange. In this paper, we investigate the impact of these air–sea fluxes on the stable water isotope (SWI) composition of water vapour in the Southern Ocean’s atmospheric boundary layer. SWIs serve as a tool to trace phase change processes involved in the atmospheric water cycle and, thus, provide important insight into moist atmospheric processes associated with extratropical cyclones. Here we combine a three-month ship-based SWI measurement data set around Antarctica with a series of regional high resolution numerical model simulations from the isotope-enabled numerical weather prediction model COSMOiso. We objectively identify atmospheric cold and warm temperature advection associated with the cold and warm sector of extratropical cyclones, respectively, based on the air–sea temperature difference applied to the measurement and the simulation data sets. A Lagrangian composite analysis of cold and warm temperature advection based on the COSMOiso simulation data is compiled to identify the main processes affecting the observed variability of the isotopic signal in marine boundary layer water vapour in the region from 35° S to 70° S. This analysis shows that the cold and warm sectors of extratropical cyclones are associated with contrasting SWI signals. Specifically, the measurements show that the median values of δ18O and δ2H in the atmospheric water vapour are 3.6 ‰ and 23.2 ‰ higher during warm than during cold advection. The median value of the second-order isotope variable deuterium excess d, which can be used as a measure of non-equilibrium processes during phase changes, is 5.9 ‰ lower during warm than during cold advection. These characteristic isotope signals during cold and warm advection reflect the opposite air–sea fluxes associated with these large-scale transport events. The trajectory-based analysis reveals that the SWI signals in the cold sector are mainly shaped by ocean evaporation. In the warm sector, the air masses experience a net loss of moisture due to dew deposition as they are advected over the relatively colder ocean, which leads to the observed low d. We show that additionally the formation of clouds and precipitation in moist adiabatically ascending warm air parcels can decrease d in boundary layer water vapour. These findings illustrate the highly variable isotopic composition in water vapour due to contrasting air–sea interactions during cold and warm advection, respectively, induced by the circulation associated with extratropical cyclones. SWIs can thus potentially be useful as tracers for meridional air advection and other characteristics associated with the dynamics of the storm tracks over interannual timescales.

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Section: B) Cosmo Iso Simulationsmentioning

confidence: 99%

The role of air–sea fluxes for the water vapour isotope signals in the cold and warm sectors of extratropical cyclones over the Southern Ocean

Thurnherr¹,

Hartmuth²,

Jansing³

et al. 2020

Preprint

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“…This can be interpreted as an under-ice version of rule (B) above. Gliders today are equipped with iceavoidance algorithms (Renfrew et al, 2019), which make similar scenarios applicable.…”

Section: Navigational Recipementioning

confidence: 99%

“…Other developments in the Argo programme further suggest a progression in this direction. Floats are increasingly being equipped with more advanced sensor suites in the biogeochemical programme (Riser et al, 2016;Roemmich et al, 2019). A new ArgoMix component with turbulence sensors (thermistors and airfoil shear probes), is also under consideration to map the spatial and temporal patterns of ocean mixing.…”

Section: Outlook -Altimetry Models and Argomentioning

confidence: 99%

“…These instruments are called floats, and approximately 4000 floats profile the oceans in the Argo programme (Roemmich et al, 2009). Their contribution to the knowledge of the oceans is substan-tial (Riser et al, 2016), yet juxtaposing the Argo programme and Stommel's vision invites a curious investigation as to why the floats lack wings. In that sense floats fall short of realizing his vision recognizing that wings would also allow for dynamic positioning.…”

Section: Introductionmentioning

confidence: 99%

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A revised ocean glider concept to realize Stommel's vision and supplement Argo floats

et al. 2020

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This paper revisits Stommel's vision for a global glider network and the Argo design specification. A concept of floats with wings, so-called slow underwater gliders, is explored. An analysis of the energy or power consumption shows that, by operating gliders with half the vehicle volume at half the speed compared to present gliders, the energy requirements for long-duration missions can be met with available battery capacities. Simulation experiments of slow gliders are conducted using the horizontal current fields from an eddy-permitting ocean reanalysis product. By employing a semi-Lagrangian, streamwise navigation whereby the glider steers at right angles to ocean currents, we show that the concept is feasible. The simulated glider tracks demonstrate the potential for efficient coverage of key oceanographic features and variability.

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“…To demonstrate the impact of the isotope composition-humidity dependence correction on the measurement, we applied the correction scheme to two datasets obtained from in situ vapour measurements during the Iceland Greenland Seas Project in March 2018 onboard an aircraft and a research vessel respectively (Renfrew et al, 2019).…”

Section: 6mentioning

confidence: 99%

Impact of isotope composition on the humidity dependency correction of water vapour isotope measurements with infra-red cavity ring-down spectrometers

Weng

Touzeau

Sodemann

2019

Preprint

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Abstract. Advances in laser spectroscopic techniques now enable high-frequency in situ measurements of the water vapour isotope composition on platforms such as ship and aircraft. However, the isotope compositions and the d-excess measured by this technique can be substantially affected by water concentrations, especially at low humidity. This measurement artefact is known as the "humidity dependency", and is commonly corrected for uniformly across all isotope compositions. Here we systematically investigate the behaviour of the humidity dependency on three commercial cavity ring-down spectrometers for different water standards within a humidity range of 500 to 23'000 ppmv. We find that the isotope compositions of measured water do have a substantial impact on the shape of the humidity dependency at low humidity (below 4'000 ppmv). This isotope composition dependency can, for example, create an offset of ±0.5 and ±6 ‰ for δ18O and δD at ~2'000 ppmv in the case of a Picarro L2130-i, resulting in an offset of 2–3 ‰ for the d-excess. We show that the combined isotope composition–humidity dependency can be expressed by a surface function, which allows to build a correction framework. The impact of this correction is illustrated for a case of aircraft measurements and ship-based measurements in cold environments. A ystematic assessment of the robustness of our findings for three laser spectrometers shows overall constant behaviour with time (for periods ranging from one month to two years), independent of the method of characterisation (discrete liquid injection and continuous vapour streaming), dry gas supply (N2 and synthetic air), or the sequence of humidity levels. Based on our analysis, we recommend a procedure for the characterisation and subsequent correction of the combined isotope composition–humidity dependency for this type of laser spectrometers when performing water vapour measurements in cold and dry conditions.

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The Iceland Greenland Seas Project

Cited by 27 publications

References 63 publications

The role of air–sea fluxes for the water vapour isotope signals in the cold and warm sectors of extratropical cyclones over the Southern Ocean

The role of air–sea fluxes for the water vapour isotope signals in the cold and warm sectors of extratropical cyclones over the Southern Ocean

A revised ocean glider concept to realize Stommel's vision and supplement Argo floats

Impact of isotope composition on the humidity dependency correction of water vapour isotope measurements with infra-red cavity ring-down spectrometers

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