Child pages
  • Online Air-Sea Interface for Soluble Species (OASISS)

Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

Current status: 

Status
subtletrue
colourGreen
titleIN TRUNK

Code is (pretty much) frozen but currently we are evaluating the air-sea exchange of currently in the trunk and will be publicly released in the next round of major update. We have tested OASISS for a number of compounds, including acetaldehyde (CH3CHO),

Footnote

Wang, S., Hornbrook, R. S., Hills, A., Emmons, L. K., Tilmes, S., Lamarque, J.‐F., et al ( 2019). Atmospheric Acetaldehyde: Importance of Air‐Sea Exchange and a Missing Source in the Remote Troposphere. Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL082034

...

Footnote

Wang, S.Apel, E. C.Schwantes, R. H.Bates, K. H.Jacob, D. J.Fischer, E. V., et al. (2020). Global Atmospheric Budget of Acetone: Air‐Sea Exchange and the Contribution to Hydroxyl RadicalsJournal of Geophysical Research: Atmospheres125, e2020JD032553. https://doi.org/10.1029/2020JD032553

 methyl nitrate (CH3ONO2), organohalogens (e.g. CHBr3, CH2Br2),

...


Point of contact: 
Siyuan Wang | NCAR

...


OVERVIEW

The ocean emits a wide range of climate-relevant gases. Most chemistry-climate models use prescribed emissions, which is simple and straightforward. But prescribed emissions usually do not respond to changes in local conditions. In this wiki we describe a new Online Air-Sea Interface for Soluble Species (OASISS) is developed for CESM | CAM-Chem to calculate the bi-directional oceanic fluxes of trace gases of interest. In brief, this model determines the direction and the magnitude of the ocean fluxes based on solubility, the physical conditions in the ocean (e.g., sea surface temperature, salinity, waves and bubbles) and the atmosphere (temperature, wind). This module is fully coupled with atmospheric chemistry and dynamics as well.

Please see this demo: LEFT panel shows the surface seawater concentration of an imaginary gas (in this example, constant surface seawater concentration is prescribed in the middle of Pacific). The MIDDLE panel shows the CAM-chem predicted surface atmospheric concentration, as you can see this compound is dispersed in the atmosphere. The RIGHT panel shows the ocean-to-air flux, with warmer colors indicating net emitting and colder colors indicating net uptaking. In regions with high seawater concentrations, the surface seawater is supersaturated, and hence the ocean is net emitting. But in near-by regions with low surface seawater concentrations, the surface seawater is undersaturated, and the ocean is net uptaking. Note: no chemicals were actually released into the Pacific in making this video!

BRIEF INTRODUCTION

 This module is mainly based on the two-layer model as previously described.

...

The bubble-mediated transfer is optional, i.e. user can switch this on or off in $caseroot/user_nl_cam.

USER INPUT

Surface seawater concentration (nanomoles per liter) of the species of interest and surface seawater salinity (parts per thousand) need to be provided in $caseroot/user_nl_cam. For example:

...

The input data (salinity and surface seawater concentrations) must be the same horizontal resolution as the model configuration. The surface seawater concentration files must cover the entire simulation time period also - better have a short "grace period" after the end of the model end date.


...

UNDER THE HOOD

In this framework, the air-sea exchange of a given soluble gas is determined by (i) solubility; (ii) kinetics; and (iii) concentration gradient at the interface. The solubility (effective Henry's law constant) is given in the FORTRAN source code, and the kinetics (e.g., the transfer velocities) will be calculated based on local physical forcing in the ocean and the atmosphere. The concentration in the atmosphere is explicitly solved in the atmospheric model, the local surface seawater concentration, ideally, should be explicitly solved in the ocean model. Unfortunately, for most of the trace gases of interest, the ocean biogeochemical processes affecting the sources and sinks in the seawater remain unclear. Therefore user needs to provide the input surface seawater concentration fields.

...

Please contact me if you are interested.

(Webpage currently under construction)

(This wiki architecture unfortunately doesn't appear to be entirely mobile-friendly)

REFERENCES

...


...


...

EXAMPLE: DMS

Most models use prescribed oceanic emission fluxes (offline) for DMS, which is less skillful since the prescribed emission fluxes are decoupled from the meteorology, atmospheric chemistry and dynamics. Over the past decades, more and more seawater DMS measurements become available, making it possible to derive observation-based surface seawater concentration product. Such surface seawater concentration fields can be used to drive the air-sea exchange of DMS. A brief test using the surface seawater DMS climatology in Lana et al. (2011)

Footnote

Lana, A., et al. (2011), An updated climatology of surface dimethlysulfide concentrations and emission fluxes in the global oceanGlobal Biogeochem. Cycles25, GB1004, doi:10.1029/2010GB003850.

is presented here, and compared to the CCMI oceanic DMS emission that is used in CESM for CMIP6. As shown in the plot below, the OASISS + Lana et al. (2011) configuration yields an annual oceanic DMS emission of 19 Tg S a-1, which is 33% higher than the DMS emission from CCMI (14 Tg S a-1).


Image Added


A few notes:

  1. OASISS + Lana et al. (2011) DMS emission (19 Tg S a-1) is comparable to the recent literature but maybe towards the lower end of the earlier studies: 24 Tg S a-1 (Lennartz et al. 2015

    Footnote

    Lennartz, S. T., Krysztofiak, G., Marandino, C. A., Sinnhuber, B.-M., Tegtmeier, S., Ziska, F., Hossaini, R., Krüger, K., Montzka, S. A., Atlas, E., Oram, D. E., Keber, T., Bönisch, H., and Quack, B.: Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions, Atmos. Chem. Phys., 15, 11753–11772, https://doi.org/10.

    1029/2019JD031288Wang, S.Apel, E. C.Schwantes, R. H.Bates, K. H.Jacob, D. J.Fischer, E. V., et al. (2020). Global Atmospheric Budget of Acetone: Air‐Sea Exchange and the Contribution to Hydroxyl RadicalsJournal of Geophysical Research: Atmospheres125, e2020JD032553. 

    5194/acp-15-11753-2015, 2015.

    ); 16-20 Tg-S/year (Gale et al. 2018

    Footnote

    Galí, M., Levasseur, M., Devred, E., Simó, R., and Babin, M.: Sea-surface dimethylsulfide (DMS) concentration from satellite data at global and regional scales, Biogeosciences, 15, 3497–3519, https://doi.org/10.

    1029/2020JD032553
  2. Johnson, M. T. (2010). A numerical scheme to calculate temperature and salinity dependent air-water transfer velocities for any gas. Ocean Sci.6(4), 913–932.
  3. Jeffery, C. D., Robinson, I. S., & Woolf, D. K. (2010). Tuning a physically-based model of the air–sea gas transfer velocity. Ocean Modelling31(1), 28–35.
  4. Mackay, D., & Yeun, A. T. K. (1983). Mass transfer coefficient correlations for volatilization of organic solutes from water. Environmental Science & Technology17(4), 211–217.
  5. 5194/bg-15-3497-2018, 2018.

    ); 15-33 Tg-S/year (Kettle and Andreae 2000

    Footnote

    Kettle, A. J., and Andreae, M. O. (2000), Flux of dimethylsulfide from the oceans: A comparison of updated data sets and flux modelsJ. Geophys. Res.105D22), 26793– 26808, doi:10.1029/2000JD900252.

    ). The difference among these can be partially explained by the transfer velocity parameterization. In OASISS, Nightingale (2000)

    Footnote

    Nightingale, P. D., Malin, G., S, L. C., Watson, A. J., Liss, P. S., Liddicoat, M. I., et al. (2000). In situ evaluation of air‐sea gas exchange parameterizations using novel conservative and volatile tracers. Global Biogeochemical Cycles14(1), 373–387.

  6. Asher, W., & Wanninkhof, R. (1998). The effect of bubble‐mediated gas transfer on purposeful dual‐gaseous tracer experiments. Journal of Geophysical Research: Oceans, 103(C5), 10555–10560. 
  7. Soloviev, A., & Schluessel, P. (2002). A Model of Air-Sea Gas Exchange Incorporating the Physics of the Turbulent Boundary Layer and the Properties of the Sea Surface. Washington DC American Geophysical Union Geophysical Monograph Series, 141–146.
  8. Millet, D. B., Guenther, A., Siegel, D. A., Nelson, N. B., Singh, H. B., de Gouw, J. A., Warneke, C., Williams, J., Eerdekens, G., Sinha, V., Karl, T., Flocke, F., Apel, E., Riemer, D. D., Palmer, P. I., and Barkley, M. (2010) Global atmospheric budget of acetaldehyde: 3-D model analysis and constraints from in-situ and satellite observations

    is used, and previous studies have used others, such as Wanninkhof (1992),

    Footnote

    Wanninkhof, R. (1992), Relationship between wind speed and gas exchange over the oceanJ. Geophys. Res.97C5), 7373– 7382, doi:10.1029/92JC00188.

    Erickson (1993).

    Footnote

    Erickson, D. J. (1993), A stability dependent theory for air‐sea gas exchangeJ. Geophys. Res.98C5), 8471– 8488, doi:10.1029/93JC00039.

     This can cause some difference, see discussions in Kettle and Andreae (2000).

  9. The annual DMS emission in our OASISS + Lana et al. (2011) configuration (19 Tg S a-1)  is 32% lower than the flux calculated in Lana et al. (2011, 28 Tg S a-1). Both are using water-side resistance from Nightingale (2000). However, Lana et al. (2011) did not include the air-side resistance, which is generally considered not important for DMS but can be substantial when cold & high wind. This may explain some difference. Moreover, Lana et al. (2011) calculated the global DMS emission with zero DMS in the atmosphere, but OASISS is fully coupled with chemistry and dynamics. A quick test with zero DMS in the air in OASISS leads to 21 Tg S a-1 (some 10% higher) DMS emission. This makes sense, since elevated DMS in the atmosphere leads to a weaker sea-to-air flux (may even push the flux downward if air concentration is high enough). Lennartz et al. (2015)

    Footnote

    Lennartz, S. T., Krysztofiak, G., Marandino, C. A., Sinnhuber, B.-M., Tegtmeier, S., Ziska, F., Hossaini, R., Krüger, K., Montzka, S. A., Atlas, E., Oram, D. E., Keber, T., Bönisch, H., and Quack, B.: Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions, Atmos. Chem. Phys.,

    10

    15,

    3405-3425

    11753–11772, https://doi.org/10.5194/acp-

    10

    15-

    3405

    11753-

    2010.

    2015, 2015.

    reported a similar trend as well.



REFERENCES

Footnotes Display


(Webpage currently under construction)

(This wiki architecture unfortunately doesn't appear to be entirely mobile-friendly)