Validation of Vertical Mixing Schemes Based on In-situ Turbulence Measurements in Tokyo Bay

Measurement of 1-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) enhanced fluorescence (FDCMU) suggested that photoinhibition of photosynthesis was frequently an artifact of in situ bottle incubations in Lake Ontario phytoplankton. In a seasonal study, FDCMU of all populations was depressed by bright light in an incubator. However, when the euphotic zone did not exceed the depth of the mixed layer, vertical transport of phytoplankton into either low-light or dark regions apparently allowed reversal of photoinhibition of FDCMU. Advantages of FDCMU as a bioassay of vertical mixing include rapidity of response time, ease of measurement in the field, and insensitivity of this parameter to changes in phosphorus status of the population. Because of seasonal changes in the photoadaptive response of natural populations, the rate constants and threshold light levels required to cause the response must be determined at each use if the method is to be quantitative.

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In situ vertical profiles of aerosol extinction, mass, and composition over the southeast United States during SENEX and SEAC<sup>4</sup>RS: observations of a modest aerosol enhancement aloft

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-7085-2015 ◽

2015 ◽

Vol 15 (12) ◽

pp. 7085-7102 ◽

Cited By ~ 40

Author(s):

N. L. Wagner ◽

C. A. Brock ◽

W. M. Angevine ◽

A. Beyersdorf ◽

P. Campuzano-Jost ◽

...

Keyword(s):

United States ◽

Mixed Layer ◽

Transition Layer ◽

Southeastern United States ◽

Vertical Mixing ◽

Organic Aerosol ◽

Vertical Profiles ◽

Free Troposphere ◽

Secondary Aerosol

Abstract. Vertical profiles of submicron aerosol from in situ aircraft-based measurements were used to construct aggregate profiles of chemical, microphysical, and optical properties. These vertical profiles were collected over the southeastern United States (SEUS) during the summer of 2013 as part of two separate field studies: the Southeast Nexus (SENEX) study and the Study of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). Shallow cumulus convection was observed during many profiles. These conditions enhance vertical transport of trace gases and aerosol and create a cloudy transition layer on top of the sub-cloud mixed layer. The trace gas and aerosol concentrations in the transition layer were modeled as a mixture with contributions from the mixed layer below and the free troposphere above. The amount of vertical mixing, or entrainment of air from the free troposphere, was quantified using the observed mixing ratio of carbon monoxide (CO). Although the median aerosol mass, extinction, and volume decreased with altitude in the transition layer, they were ~10 % larger than expected from vertical mixing alone. This enhancement was likely due to secondary aerosol formation in the transition layer. Although the transition layer enhancements of the particulate sulfate and organic aerosol (OA) were both similar in magnitude, only the enhancement of sulfate was statistically significant. The column integrated extinction, or aerosol optical depth (AOD), was calculated for each individual profile, and the transition layer enhancement of extinction typically contributed less than 10 % to the total AOD. Our measurements and analysis were motivated by two recent studies that have hypothesized an enhanced layer of secondary aerosol aloft to explain the summertime enhancement of AOD (2–3 times greater than winter) over the southeastern United States. The first study attributes the layer aloft to secondary organic aerosol (SOA) while the second study speculates that the layer aloft could be SOA or secondary particulate sulfate. In contrast to these hypotheses, the modest enhancement we observed in the transition layer was not dominated by OA and was not a large fraction of the summertime AOD.

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Turbulence and hypoxia contribute to dense biological scattering layers in a Patagonian fjord system

Ocean Science ◽

10.5194/os-14-1185-2018 ◽

2018 ◽

Vol 14 (5) ◽

pp. 1185-1206 ◽

Cited By ~ 3

Author(s):

Iván Pérez-Santos ◽

Leonardo Castro ◽

Lauren Ross ◽

Edwin Niklitschek ◽

Nicolás Mayorga ◽

...

Keyword(s):

Kinetic Energy ◽

Water Column ◽

Turbulent Kinetic Energy ◽

Tidal Flow ◽

Vertical Mixing ◽

Acoustic Doppler Current Profiler ◽

Marine Species ◽

Eddy Diffusivity ◽

Diel Vertical Migrations

Abstract. The aggregation of plankton species along fjords can be linked to physical properties and processes such as stratification, turbulence and oxygen concentration. The goal of this study is to determine how water column properties and turbulent mixing affect the horizontal and vertical distributions of macrozooplankton along the only northern Patagonian fjord known to date, where hypoxic conditions occur in the water column. Acoustic Doppler current profiler moorings, scientific echo-sounder transects and in situ plankton abundance measurements were used to study macrozooplankton assemblages and migration patterns along Puyuhuapi Fjord and Jacaf Channel in Chilean Patagonia. The dissipation of turbulent kinetic energy was quantified through vertical microstructure profiles collected throughout time in areas with high macrozooplankton concentrations. The acoustic records and in situ macrozooplankton data revealed diel vertical migrations (DVM) of siphonophores, chaetognaths and euphausiids. In particular, a dense biological backscattering layer was observed along Puyuhuapi Fjord between the surface and the top of the hypoxic boundary layer (∼100 m), which limited the vertical distribution of most macrozooplankton and their DVM, generating a significant reduction of habitat. Aggregations of macrozooplankton and fishes were most abundant around a submarine sill in Jacaf Channel. In this location macrozooplankton were distributed throughout the water column (0 to ∼200 m), with no evidence of a hypoxic boundary due to the intense mixing near the sill. In particular, turbulence measurements taken near the sill indicated high dissipation rates of turbulent kinetic energy (ε∼10-5 W kg−1) and vertical diapycnal eddy diffusivity (Kρ∼10-3 m2 s−1). The elevated vertical mixing ensures that the water column is well oxygenated (3–6 mL L−1, 60 %–80 % saturation), creating a suitable environment for macrozooplankton and fish aggregations. Turbulence induced by tidal flow over the sill apparently enhances the interchange of nutrients and oxygen concentrations with the surface layer, creating a productive environment for many marine species, where the prey–predator relationship might be favored.

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A comparison of vertical mixing schemes embedded in an OGCM with application to air-sea interactions and the evolution of SST anomalies

Meteorology and Atmospheric Physics ◽

10.1007/bf01080880 ◽

1993 ◽

Vol 51 (1-2) ◽

pp. 55-71 ◽

Cited By ~ 3

Author(s):

C. J. C. Reason ◽

I. K�hnel ◽

B. Henderson-Sellers

Keyword(s):

Vertical Mixing ◽

Mixing Schemes ◽

Sst Anomalies

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Comparison of ocean vertical mixing schemes in the Max Plank Institute Earth System Model (MPI-ESM1.2)

10.5194/gmd-2020-202 ◽

2020 ◽

Author(s):

Oliver Gutjahr ◽

Nils Brüggemann ◽

Helmuth Haak ◽

Johann H. Jungclaus ◽

Dian A. Putrasahan ◽

...

Keyword(s):

Vertical Mixing ◽

Global Scale ◽

Earth System Model ◽

System Model ◽

The Arctic ◽

Earth System ◽

Max Planck ◽

Vertical Diffusion ◽

Mixing Schemes ◽

Mean State

Abstract. We compare the effects of four different ocean vertical mixing schemes on the ocean mean state simulated by the Max Planck Institute Earth System Model (MPI-ESM1.2) in the framework of the Community Vertical Mixing (CVMix) library. Besides the PP and KPP scheme, we implemented the TKE scheme and a recently developed prognostic scheme for internal wave energy and its dissipation (IDEMIX) to replace the often assumed constant background diffusivity in the ocean interior. We analyse in particular the effects of IDEMIX on the ocean mean state, when combined with TKE (TKE+IDEMIX). In general, we find little sensitivity of the ocean surface, but considerable effects for the interior ocean. Overall, we cannot classify any scheme as superior, because they modify biases that vary by region or variable, but produce a similar pattern on the global scale. However, using a more realistic and energetically consistent scheme (TKE+IDEMIX) produces a more heterogeneous pattern of vertical diffusion, with lower diffusivity in deep and flat-bottom basins and elevated turbulence over rough topography. In addition, TKE+IDEMIX improves the circulation in the Nordic Seas and Fram Strait, thus reducing the warm bias of the Atlantic water (AW) layer in the Arctic Ocean to a similar extent as has been demonstrated with eddy-resolving ocean models. We conclude that although shortcomings due to model resolution determine the global-scale bias pattern, the choice of the vertical mixing scheme may play an important role for regional biases.

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Obstruction Influence on Low-Speed, In-Situ Stratospheric Turbulence Measurements

AIAA AVIATION 2021 FORUM ◽

10.2514/6.2021-2698 ◽

2021 ◽

Author(s):

Joseph L. Pointer ◽

Kenneth E. Jansen ◽

Brian M. Argrow ◽

Dale A. Lawrence

Keyword(s):

Turbulence Measurements ◽

Low Speed

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Development of CarbonTracker Europe-CH<sub>4</sub> – Part 2: global methane emission estimates and their evaluation for 2000–2012

10.5194/gmd-2016-182 ◽

2016 ◽

Cited By ~ 2

Author(s):

Aki Tsuruta ◽

Tuula Aalto ◽

Leif Backman ◽

Janne Hakkarainen ◽

Ingrid T. van der Laan-Luijkx ◽

...

Keyword(s):

North American ◽

Transport Model ◽

Vertical Mixing ◽

Total Carbon ◽

In Situ Observation ◽

Convection Scheme ◽

Temperate Region ◽

Northern Latitude ◽

The North

Abstract. Gobal methane emissions were estimated for 2000–2012 using the CarbonTracker Europe-CH4 (CTE-CH4) data assimilation system. In CTE-CH4, the anthropogenic and biosphere emissions of CH4 are simultaneously constrained by global atmospheric in-situ methane mole fraction observations. We use three configurations developed in Tsuruta et al. (2016) to assess the sensitivity of the CH4 flux estimates to (a) the number of unknown flux scaling factors to be optimized which in turn depends on the choice of underlying land-ecosystem map, and (b) on the parametrization of vertical mixing in the 30 atmospheric transport model TM5. The posterior emission estimates were evaluated by comparing simulations to surface in-situ observation sites, to profile observations made by aircraft, to dry air total column-averaged mole fractions (XCH4) observations from the Total Carbon Column Observing Network (TCCON), and to XCH4 retrievals from the Greenhouse gases Observing SATellite (GOSAT). Our estimated posterior mean global total emissions during 2000–2012 are 516 ± 51 Tg CH4 yr−1, and emission estimates during 2007–2012 are 18 Tg CH4 yr−1 greater than those from 2001–2006, mainly driven by an 35 increase in emissions from the south America temperate region, the Asia temperate region and Asia tropics. The sensitivity of the flux estimates to the underlying ecosystem map was large for the Asia temperate region and Australia, but not significant in the northern latitude regions, i.e. the north American boreal region, the north American temperate region and Europe. Instead, the posterior estimates for the northern latitude regions show larger sensitivity to the choice of convection scheme in TM5. The Gregory et al. (2000) mixing scheme with faster interhemispheric exchange leads to higher estimated CH4 emissions at northern latitudes, and lower emissions in southern latitudes, compared to the estimates using Tiedtke (1989) convection scheme. Our evaluation with non-assimilated observations showed that posterior mole fractions were better matched with the 5 observations when Gregory et al. (2000) convection scheme was used.

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On the Variability of the Circulation and Water Mass Properties in the Eastern Levantine Sea between September 2016–August 2017

Water ◽

10.3390/w11091741 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1741 ◽

Cited By ~ 5

Author(s):

Mauri ◽

Sitz ◽

Gerin ◽

Poulain ◽

Hayes ◽

...

Keyword(s):

High Salinity ◽

Autonomous Systems ◽

Vertical Mixing ◽

The North ◽

Levantine Sea ◽

Surface Circulation ◽

Basin Scale ◽

Geographical Position ◽

Surface Drifters

The surface circulation and the thermohaline properties of the water masses of the eastern Levantine Sea (Mediterranean Sea) were monitored with mobile autonomous systems (surface drifters and gliders) during the period September 2016–August 2017. The drifters provided data for more than a year and revealed complex circulation features at scales ranging from the basin scale to the sub-mesoscale. Three drifters were captured in a semi-permanent gyre (Cyprus Eddy) allowing a quantitative study of its kinematics. During the experiment, three gliders were operated, in two different periods: September to December 2016 and February to March 2017. The autonomous instruments crossed the prevailing sub-basin structures several times. The collected in-situ observations were analyzed and interpreted in concert with remote sensing products (sea surface temperature and altimetry). The evolution of some of the prevailing features confirmed the complexity of the circulation of the basin. The Cyprus Eddy is the most persistent anticyclone, moving its geographical position and sometimes merging with the North Shikmona Eddy in a bigger structure. The gliders sampled this wide anticyclonic feature revealing its vertical structure in the two different periods. In fall, in stratified conditions, a high salinity core is evident below the thermocline. The isopycnals are characterized by an upward bending over the high salinity lens and a downward bending below it, typical of an anticyclonic modewater eddy. In winter, the core disappears following the vertical mixing that, homogenizes the upper Cyprus Eddy water down to 300 m.

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Evaluation of wake influence on high-resolution balloon-sonde measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-12-4191-2019 ◽

2019 ◽

Vol 12 (8) ◽

pp. 4191-4210 ◽

Cited By ~ 3

Author(s):

Jens Söder ◽

Michael Gerding ◽

Andreas Schneider ◽

Andreas Dörnbrack ◽

Henrike Wilms ◽

...

Keyword(s):

High Resolution ◽

Uncertainty Analysis ◽

Atmospheric Turbulence ◽

Evaluation Tool ◽

Turbulence Measurements ◽

Wake Effects ◽

Humidity Measurements ◽

Average Probability ◽

Vertical Winds

Abstract. Balloons are used for various in situ measurements in the atmosphere. On turbulence measurements from rising balloons there is a potential for misinterpreting wake-created fluctuations in the trail of the balloon for atmospheric turbulence. These wake effects have an influence on temperature and humidity measurements from radiosondes as well. The primary aim of this study is to assess the likelihood for wake encounter on the payload below a rising balloon. Therefore, we present a tool for calculating this probability based on radiosonde wind data. This includes a retrieval of vertical winds from the radiosonde and an uncertainty analysis of the wake assessment. Our wake evaluation tool may be used for any balloon–gondola distance and provides a significant refinement compared to existing assessments. We have analysed wake effects for various balloon–gondola distances applying atmospheric background conditions from a set of 30 radiosondes. For a standard radiosonde we find an average probability for wake encounter of 28 %, pointing out the importance of estimating wake effects on sounding balloons. Furthermore, we find that even millimetre-sized objects in the payload can have significant effects on high-resolution turbulence measurements, if they are located upstream of the turbulence sensor.

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