scholarly journals Methyl iodide production in the open ocean

2013 ◽  
Vol 10 (11) ◽  
pp. 17549-17595 ◽  
Author(s):  
I. Stemmler ◽  
I. Hense ◽  
B. Quack ◽  
E. Maier-Reimer
Keyword(s):  
Methyl Iodide ◽  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Global Scale ◽  
Phytoplankton Production ◽  
Boreal Winter ◽  
Photochemical Degradation ◽  
Data Set

Abstract. Production pathways of the prominent volatile organic halogen compound methyl iodide (CH3I) are not fully understood. Previous model studies suggest either production via photochemical degradation of organic material or rather phytoplankton production. Correlations between biological and environmental variables derived from observations also suggest both production pathways. In this study we aim to address this question of source mechanisms with a global three-dimensional ocean general circulation model including biogeochemistry (MPIOM-HAMOCC) by carrying out a series of sensitivity experiments. Simulated distribution patterns and emissions of CH3I differ largely for the different production pathways. However, the evaluation of our model results with observations from a newly available global data set shows that observed surface concentrations of CH3I can be best explained by the photochemical production pathway. Our results further emphasize that correlations between CH3I and abiotic or biotic factors do not necessarily provide meaningful insights concerning the source of origin. Overall, we find a net global annual CH3I air–sea flux that ranges between 70 and 260 Gg yr−1. Hence, at the global scale the ocean is a net source of methyl iodide for the atmosphere, though in some regions in boreal winter fluxes are of opposite direction (from the atmosphere to the ocean).

scholarly journals Methyl iodide production in the open ocean

2014 ◽  
Vol 11 (16) ◽  
pp. 4459-4476 ◽  
Author(s):  
I. Stemmler ◽  
I. Hense ◽  
B. Quack ◽  
E. Maier-Reimer
Keyword(s):  
Methyl Iodide ◽  
General Circulation ◽  
Circulation Model ◽  
Global Scale ◽  
Global Ocean ◽  
Phytoplankton Production ◽  
Boreal Winter ◽  
Max Planck ◽  
Data Set ◽  
Carbon Cycle Model

Abstract. Production pathways of the prominent volatile organic halogen compound methyl iodide (CH3I) are not fully understood. Based on observations, production of CH3I via photochemical degradation of organic material or via phytoplankton production has been proposed. Additional insights could not be gained from correlations between observed biological and environmental variables or from biogeochemical modeling to identify unambiguously the source of methyl iodide. In this study, we aim to address this question of source mechanisms with a three-dimensional global ocean general circulation model including biogeochemistry (MPIOM–HAMOCC (MPIOM – Max Planck Institute Ocean Model HAMOCC – HAMburg Ocean Carbon Cycle model)) by carrying out a series of sensitivity experiments. The simulated fields are compared with a newly available global data set. Simulated distribution patterns and emissions of CH3I differ largely for the two different production pathways. The evaluation of our model results with observations shows that, on the global scale, observed surface concentrations of CH3I can be best explained by the photochemical production pathway. Our results further emphasize that correlations between CH3I and abiotic or biotic factors do not necessarily provide meaningful insights concerning the source of origin. Overall, we find a net global annual CH3I air–sea flux that ranges between 70 and 260 Gg yr−1. On the global scale, the ocean acts as a net source of methyl iodide for the atmosphere, though in some regions in boreal winter, fluxes are of the opposite direction (from the atmosphere to the ocean).

scholarly journals Seasonal variations of the semi-diurnal and diurnal tides in the MLT: multi-year MF radar observations from 2–70° N, modelled tides (GSWM, CMAM)

2002 ◽  
Vol 20 (5) ◽  
pp. 661-677 ◽  
Author(s):  
A. H. Manson ◽  
C. Meek ◽  
M. Hagan ◽  
J. Koshyk ◽  
S. Franke ◽  
...  
Keyword(s):  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Wave Model ◽  
Global Scale ◽  
Diurnal Tide ◽  
Data Set ◽  
Height Range ◽  
Christmas Island ◽  
Tidal Data

Abstract. In an earlier paper (Manson et al., 1999a) tidal data (1990–1997) from six Medium Frequency Radars (MFR) were compared with the Global Scale Wave Model (GSWM, original 1995 version). The radars are located between the equator and high northern latitudes: Christmas Island (2° N), Hawaii (22° N), Urbana (40° N), London (43° N), Saskatoon (52° N) and Tromsø (70° N). Common harmonic analysis was applied, to ensure consistency of amplitudes and phases in the 75–95 km height range. For the diurnal tide, seasonal agreements between observations and model were excellent while for the semi-diurnal tide the seasonal transitions between clear solstitial states were less well captured by the model. Here the data set is increased by the addition of two locations in the Pacific-North American sector: Yamagawa 31° N, and Wakkanai 45° N. The GSWM model has undergone two additional developments (1998, 2000) to include an improved gravity wave (GW) stress parameterization, background winds from UARS systems and monthly tidal forcing for better characterization of seasonal change. The other model, the Canadian Middle Atmosphere Model (CMAM) which is a General Circulation Model, provides internally generated forcing (due to ozone and water vapour) for the tides. The two GSWM versions show distinct differences, with the 2000 version being either closer to, or further away from, the observations than the original 1995 version. CMAM provides results dependent upon the GW parameterization scheme inserted, but one of the schemes provides very useful tides, especially for the semi-diurnal component.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

scholarly journals Simulation of satellite lidar and radiometer retrievals of a general circulation model three-dimensional cloud data set

1998 ◽  
Vol 103 (D20) ◽  
pp. 26025-26039 ◽  
Author(s):  
M. Doutriaux-Boucher ◽  
J. Pelon ◽  
V. Trouillet ◽  
G. Sèze ◽  
H. Le Treut ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Data Set ◽  
Cloud Data

Towards AOD1B RL07

2020 ◽  
Author(s):  
Linus Shihora ◽  
Henryk Dobslaw
Keyword(s):  
General Circulation ◽  
A Priori ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Temporal Variations ◽  
Ocean Dynamics ◽  
Global Ocean ◽  
Ocean Bottom ◽  
Data Set ◽  
Priori Information

<p>The Atmosphere and Ocean De-Aliasing Level-1B (AOD1B) product provides a priori information about temporal variations in the Earth's gravity field caused by global mass variability in the atmosphere and ocean and is routinely used as background model in satellite gravimetry. The current version 06 provides Stokes coefficients expanded up to d/o 180 every 3 hours. It is based on ERA-Interim and the ECMWF operational model for the atmosphere, and simulations with the global ocean general circulation model MPIOM consistently forced with the fields from the same atmospheric data-set.</p> <p>We here present preliminary numerical experiments in the development towards a new release 07 of AOD1B. The experiments are performed with the TP10 configuration of MPIOM and include (I) new hourly atmospheric forcing based on the new ERA-5 reanalysis from ECMWF; (II) an improved bathymetry around Antarctica including cavities under the ice shelves; and (III) an explicit implementation of the feedback effects of self-attraction and loading to ocean dynamics. The simulated ocean bottom pressure variability is discussed with respect to AOD1B version 6 as well as in situ ocean observations. A preliminary timeseries of hourly AOD1B-like coefficients for the year 2019 that incorporate the above mentioned improvements will be made available for testing purposes.</p>

scholarly journals The Three-Dimensional Steady Circulation in a Homogenous Ocean Induced by a Stationary Hurricane

2010 ◽  
Vol 40 (7) ◽  
pp. 1441-1457 ◽  
Author(s):  
Zhu Min Lu ◽  
Rui Xin Huang
Keyword(s):  
Analytical Solution ◽  
General Circulation ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Coriolis Parameter ◽  
Middle Latitudes ◽  
Oceanic Response ◽  
Stratified Ocean

Abstract Based on the classical Ekman layer theory, a simple analytical solution of the steady flow induced by a stationary hurricane in a homogenous ocean is discussed. The model consists of flow converging in an inward spiral in the deeper layer and diverging in the upper layer. The simple analytical model indicates that both the upwelling flux and the horizontal transport increase linearly with increasing radius of maximum winds. Furthermore, they both have a parabolic relationship with the maximum wind speed. The Coriolis parameter also affects the upwelling flux: the response to a hurricane is stronger at low latitudes than that at middle latitudes. Numerical solutions based on a regional version of an ocean general circulation model are similar to the primary results obtained through the analytical solution. Thus, the simplifications made in formulating the analytical solution are reasonable. Although the analytical solution in this paper is sought for a rather idealized ocean, it can help to make results from the more complicated numerical model understandable. These conceptual models provide a theoretical limit structure of the oceanic response to a moving hurricane over a stratified ocean.

scholarly journals Effects of mesoscale eddies on global ocean distributions of CFC-11, CO<sub>2</sub> and Δ<sup>14</sup>C

2006 ◽  
Vol 3 (4) ◽  
pp. 1011-1063
Author(s):  
Z. Lachkar ◽  
J. C. Orr ◽  
J.-C. Dutay ◽  
P. Delecluse
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Global Scale ◽  
Global Ocean ◽  
Residual Circulation ◽  
Mean Flow ◽  
Meridional Transport ◽  
Anthropogenic Co2 ◽  
Short Time

Abstract. Global-scale tracer simulations are typically made at coarse resolution without explicitly modeling eddies. Here we ask what role do eddies play in ocean uptake, storage, and meridional transport of transient tracers. We made global anthropogenic transient-tracer simulations in non-eddying (2°cosφ×2°, ORCA2) and eddying (½°cosφ×½°, ORCA05) versions of the ocean general circulation model OPA9. We focus on the Southern Ocean where tracer air-sea fluxes are largest. Eddies have little effect on global and regional bomb Δ14C uptake and storage. Yet for anthropogenic CO2 and CFC-11, increased eddy activity reduces southern extratropical uptake by 28% and 25% respectively. There is a similar decrease in corresponding inventories, which provides better agreement with observations. With higher resolution, eddies strengthen upper ocean vertical stratification and reduce excessive ventilation of intermediate waters by 20% between 60° S and 40° S. By weakening the Residual Circulation, i.e., the sum of Eulerian mean flow and the opposed eddy-induced flow, eddies reduce the supply of tracer-impoverished deep waters to the surface near the Antarctic divergence, thus reducing the air-sea tracer flux. Consequently, inventories for both CFC-11 and anthropogenic CO2 decrease because their mixed layer concentrations in that region equilibrate with the atmosphere on relatively short time scales (15 days and 6 months, respectively); conversely, the slow air-sea equilibration of bomb Δ14C of 6 years, gives surface waters little time to exchange with the atmosphere before they are subducted.

Retrieving the Ocean Interior Structure from Surface Data:FOAGRNN and SQG-mEOF-R

2020 ◽  
Author(s):  
Huizan Wang ◽  
Ren Zhang ◽  
Senliang Bao ◽  
Henqian Yan ◽  
Weimin Zhang ◽  
...  
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Sea Surface ◽  
Generalized Regression Neural Network ◽  
Northwest Pacific ◽  
Interior Structure ◽  
Nonlinear Method ◽  
Surface Data

&lt;p&gt;As many oceanic observations can only reflect the sea surface, such as satellite data, the retrieval of the ocean interior structure from sea surface information is of great importance for us to understand the three-dimensional ocean. In order to retrieve the three-dimensional salinity and density&amp;#160;structure from surface data, two new method are proposed as follows. One proposed method is called generalized regression neural network with the fruit fly optimization&amp;#160;algorithm (FOAGRNN), which is a nonlinear method and used to estimate subsurface salinity profiles from&amp;#160;sea surface parameters. Compared with linear methodology, the estimated salinity profiles from the&amp;#160;FOAGRNN method are in better agreement with the measured profiles at the halocline.The&amp;#160;results suggest a potential new approach for salinity profile estimation derived from&amp;#160;sea surface data. The other proposed method is called SQG-mEOF-R, which estimate the interior density from the sea surface density (SSD) and sea surface height (SSH)&amp;#160;by combining&amp;#160;the dynamical surface trapped mode derived from the Surface Quasi-Geostrophic (SQG) function with the statistical mode calculated from multivariate EOF reconstruction (mEOF-R) method and. This method is applied to the eddy-resolving OFES (Ocean General Circulation Model For the Earth simulator) simulation and compared with the conventional SQG or isQG (interior plus SQG) and mEOF-R methods. The results manifest that, no matter in the NorthWest Pacific (NWP) region dominated by surface-intensified eddies or the SouthEast Pacific (SEP) region characterized by subsurface-intensified eddies, SQG-mEOF-R perform a robust work in mesoscale density reconstruction.&lt;/p&gt;

scholarly journals Volcanic forcing for climate modeling: a new microphysics-based data set covering years 1600–present

2014 ◽  
Vol 10 (1) ◽  
pp. 359-375 ◽  
Author(s):  
F. Arfeuille ◽  
D. Weisenstein ◽  
H. Mack ◽  
E. Rozanov ◽  
T. Peter ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Global Scale ◽  
Stratospheric Aerosol ◽  
Set Covering ◽  
Data Set ◽  
Volcanic Forcing

Abstract. As the understanding and representation of the impacts of volcanic eruptions on climate have improved in the last decades, uncertainties in the stratospheric aerosol forcing from large eruptions are now linked not only to visible optical depth estimates on a global scale but also to details on the size, latitude and altitude distributions of the stratospheric aerosols. Based on our understanding of these uncertainties, we propose a new model-based approach to generating a volcanic forcing for general circulation model (GCM) and chemistry–climate model (CCM) simulations. This new volcanic forcing, covering the 1600–present period, uses an aerosol microphysical model to provide a realistic, physically consistent treatment of the stratospheric sulfate aerosols. Twenty-six eruptions were modeled individually using the latest available ice cores aerosol mass estimates and historical data on the latitude and date of eruptions. The evolution of aerosol spatial and size distribution after the sulfur dioxide discharge are hence characterized for each volcanic eruption. Large variations are seen in hemispheric partitioning and size distributions in relation to location/date of eruptions and injected SO2 masses. Results for recent eruptions show reasonable agreement with observations. By providing these new estimates of spatial distributions of shortwave and long-wave radiative perturbations, this volcanic forcing may help to better constrain the climate model responses to volcanic eruptions in the 1600–present period. The final data set consists of 3-D values (with constant longitude) of spectrally resolved extinction coefficients, single scattering albedos and asymmetry factors calculated for different wavelength bands upon request. Surface area densities for heterogeneous chemistry are also provided.

scholarly journals Sensitivity of the ocean circulation model to the k–omega vertical turbulence parametrization

2019 ◽  
Vol 55 (5) ◽  
pp. 103-113
Author(s):  
V. B. Zalesny ◽  
S. N. Moshonkin
Keyword(s):  
Ocean Circulation ◽  
General Circulation ◽  
Splitting Method ◽  
Three Dimensional ◽  
Numerical Algorithms ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Turbulence Parametrization ◽  
Vertical Turbulence ◽  
Model Equations

Ocean general circulation model (OGCM) of the INM RAS with embedded k turbulent model is developed. The solution of the k model equations depends on the frequencies of buoyancy and velocity shift which are generated by the OGCM. The coefficients of vertical turbulence in OGCM depend on k and omega. The numerical algorithms of both models are based on the splitting method for physical processes. The model equations are split into two stages, describing the three-dimensional transport-diffusion of the kinetic energy of turbulence and frequency and their local generation-dissipation. The system of ordinary differential equations arising at the second stage is solved analytically, which ensures the efficiency of the algorithm. Analytical solution also written for the vertical turbulence coefficient equation. The model is used to study the sensitivity of the model circulation of the North AtlanticArctic Ocean to variations in the parameters of vertical turbulence. Experiments show that varying the coefficients of the analytical model solution can improve the adequacy of the simulation.

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