Circulation and Temperature Structure in Large Marine Enclosures

1977 ◽  
Vol 34 (8) ◽  
pp. 1095-1104 ◽  
Author(s):  
J. H. Steele ◽  
D. M. Farmer ◽  
E. W. Henderson
Keyword(s):  
Vertical Mixing ◽  
Temperature Structure ◽  
Temperature Profiles ◽  
Turbulent Diffusivity ◽  
Mixing Energy ◽  
Physical Measurements ◽  
Average Coefficient ◽  
Different Depths ◽  
External Fluctuations ◽  
Shed Light

Certain physical measurements intended to shed light on the circulation in large plastic enclosures (60–2000 m3) induced by the changing environment in which they are moored are described. Layers of dye were generally seen to diffuse vertically although some important advection effects were also observed. Estimates of an average coefficient of turbulent diffusivity yielded values in the range.05–.26 cm2∙s−1.Measurements taken with recording thermistor chains both inside and outside the enclosures show strong damping of external fluctuations with periods significantly less than 1 day. Various possible sources of mixing energy are considered and it is concluded that thermal forcing through the wall may be significant and could account for the observed range of coefficients.The significance of the observed mixing and circulation to the ecology of the enclosures is discussed. Of particular importance is the vertical mixing of nutrients that influences phytoplankton sinking rates and thus plays a crucial role in determining variations in algal concentration at different depths. Key words: mixing, enclosures, controlled ecosystem pollution experiment, circulation, temperature profiles

scholarly journals South Adriatic Recipes: Estimating the Vertical Mixing in the Deep Pit

2020 ◽  
Vol 7 ◽  
Author(s):  
Vanessa Cardin ◽  
Achim Wirth ◽  
Maziar Khosravi ◽  
Miroslav Gačić
Keyword(s):  
Time Series ◽  
Heat Equation ◽  
Gravity Current ◽  
Vertical Mixing ◽  
Temperature Structure ◽  
Temperature Profiles ◽  
Eof Analysis ◽  
Vertical Temperature ◽  
Current Events ◽  
Sill Depth

The available historical oxygen data show that the deepest part of the South Adriatic Pit remains well-ventilated despite the winter convection reaching only the upper 700 m depth. Here, we show that the evolution of the vertical temperature structure in the deep South Adriatic Pit (dSAP) below the Otranto Strait sill depth (780 m) is described well by continuous diffusion, a continuous forcing by heat fluxes at the upper boundary (Otranto Strait sill depth) and an intermittent forcing by rare (several per decade) deep convective and gravity-current events. The analysis is based on two types of data: (i) 13-year observational data time series (2006–2019) at 750, 900, 1,000, and 1,200 m depths of the temperature from the E2M3A Observatory and (ii) 55 vertical profiles (1985–2019) in the dSAP. The analytical solution of the gravest mode of the heat equation compares well to the temperature profiles, and the numerical integration of the resulting forced heat equation compares favorably to the temporal evolution of the time-series data. The vertical mixing coefficient is obtained with three independent methods. The first is based on a best fit of the long-term evolution by the numerical diffusion-injection model to the 13-year temperature time series in the dSAP. The second is obtained by short-time (daily) turbulent fluctuations and a Prandtl mixing length approximation. The third is based on the zero and first modes of an Empirical Orthogonal Function (EOF) analysis of the time series between 2014 and 2019. All three methods are compared, and a diffusivity of approximately κ = 5 · 10−4m2s−1 is obtained. The eigenmodes of the homogeneous heat equation subject to the present boundary conditions are sine functions. It is shown that the gravest mode typically explains 99.5% of the vertical temperature variability (the first three modes typically explain 99.85%) of the vertical temperature profiles at 1 m resolution. The longest time scale of the dissipative dynamics in the dSAP, associated with the gravest mode, is found to be approximately 5 years. The first mode of the EOF analysis (85%) represents constant heating over the entire depth, and the zero mode is close to the parabolic profile predicted by the heat equation for such forcing. It is shown that the temperature structure is governed by continuous warming at the sill depth and deep convection and gravity current events play less important roles. The simple model presented here allows evaluation of the response of the temperature in the dSAP to different forcings derived from climate change scenarios, as well as feedback on the dynamics in the Adriatic and the Mediterranean Sea.

scholarly journals South Adriatic Recipes: Estimating the Vertical Mixing in the Deep Pit

2021 ◽  
Author(s):  
Achim Wirth ◽  
Vanessa Cardin ◽  
Maziar Khosravi ◽  
Miroslav Gačić
Keyword(s):  
Time Series ◽  
Heat Equation ◽  
Gravity Current ◽  
Vertical Mixing ◽  
Temperature Structure ◽  
Temperature Profiles ◽  
Eof Analysis ◽  
Vertical Temperature ◽  
Current Events ◽  
Sill Depth

<p>The available historical oxygen data show that the deepest part of the South Adriatic Pit remains well-ventilated despite the winter convection reaching only the upper 700 m depth. Here, we show that the evolution of the vertical temperature structure in the deep South Adriatic Pit (dSAP) below the Otranto Strait sill depth (780 m) is described well by continuous diffusion, a continuous forcing by heat fluxes at the upper boundary (Otranto Strait sill depth) and an intermittent forcing by rare (several per decade) deep convective and gravity-current events. The analysis is based on two types of data: (i) 13-year observational data time series (2006–2019) at 750, 900, 1,000, and 1,200 m depths of the temperature from the E2M3A Observatory and (ii) 55 vertical profiles (1985–2019) in the dSAP. The analytical solution of the gravest mode of the heat equation compares well to the temperature profiles, and the numerical integration of the resulting forced heat equation compares favorably to the temporal evolution of the time-series data. The vertical mixing coefficient is obtained with three independent methods. The first is based on a best fit of the long-term evolution by the numerical diffusion-injection model to the 13-year temperature time series in the dSAP. The second is obtained by short-time (daily) turbulent fluctuations and a Prandtl mixing length approximation. The third is based on the zero and first modes of an Empirical Orthogonal Function (EOF) analysis of the time series between 2014 and 2019. All three methods are compared, and a diffusivity of approximately κ = 5 · 10<sup>−4</sup>m<sup>2</sup>s<sup>−1</sup> is obtained. The eigenmodes of the homogeneous heat equation subject to the present boundary conditions are sine functions. It is shown that the gravest mode typically explains 99.5% of the vertical temperature variability (the first three modes typically explain 99.85%) of the vertical temperature profiles at 1 m resolution. The longest time scale of the dissipative dynamics in the dSAP, associated with the gravest mode, is found to be approximately 5 years. The first mode of the EOF analysis (85%) represents constant heating over the entire depth, and the zero mode is close to the parabolic profile predicted by the heat equation for such forcing. It is shown that the temperature structure is governed by continuous warming at the sill depth and deep convection and gravity current events play less important roles. The simple model presented here allows evaluation of the response of the temperature in the dSAP to different forcings derived from climate change scenarios, as well as feedback on the dynamics in the Adriatic and the Mediterranean Sea.</p>

scholarly journals Field measurement of ground temperatures in Bandung: devices and the results of measurement

2020 ◽  
Vol 200 ◽  
pp. 02009
Author(s):  
Muhammad Nur Fajri Alfata ◽  
Amalia Nurjannah
Keyword(s):  
Temperature Sensor ◽  
Field Measurement ◽  
Ground Temperature ◽  
Passive Cooling ◽  
Temperature Profiles ◽  
Temperature Changes ◽  
Ground Temperatures ◽  
Different Depths ◽  
Measurement Devices ◽  
Main Component

Ground cooling is considered to be one of the passive cooling strategies in buildings although its application is rarely found in Indonesia. Effectiveness of this strategy depend on the ground temperature profiles. Meanwhile, comprehensive data of ground temperature as a basis of design for ground cooling are still rarely found in Indonesia. This research aims to develop the measurement devices for collecting ground temperatures data and to investigate the ground temperatures in different depths (i.e., 1m, 2m, …, 9m). For measurement, an instrumentation system was developed with the main component of Arduino Mega 2560 as microcontroller. T-type thermocouples with diameter of 0, 5mm mounted in the metal cones were used as the temperature sensor and placed at the different depths. The field measurement was conducted from August to November 2019 in Bandung, West Java, Indonesia. This study demonstrated that the developed instrument system had good performance both in measuring and data acquisition. Model equation was developed to predict the ground temperature at certain depth regardless ground materials and humidity level. The results indicated that the ground temperature significantly lower to 5m-depth. However, the reduction of the temperature after 5m was not significant; the deeper the ground, the temperature changes are negligible.

scholarly journals Assessing spectra and thermal inversions due to TiO in hot Jupiter atmospheres

2020 ◽  
Vol 496 (3) ◽  
pp. 3870-3886 ◽  
Author(s):  
Anjali A A Piette ◽  
Nikku Madhusudhan ◽  
Laura K McKemmish ◽  
Siddharth Gandhi ◽  
Thomas Masseron ◽  
...  
Keyword(s):  
Near Infrared ◽  
Vertical Mixing ◽  
Emission Spectra ◽  
Primary Source ◽  
Temperature Structure ◽  
Atmospheric Conditions ◽  
Atmospheric Models ◽  
Line List ◽  
Hot Jupiters ◽  
Work First

ABSTRACT Recent detections of thermal inversions in the dayside atmospheres of some hot Jupiters are motivating new avenues to understand the interplay between their temperature structures and other atmospheric conditions. In particular, TiO has long been proposed to cause thermal inversions in hot Jupiters, depending on other factors such as stellar irradiation, C/O, and vertical mixing. TiO also has spectral features in the optical and near-infrared that have been detected. However, interpretations of TiO signatures rely on the accuracy of TiO opacity used in the models. The recently reported toto TiO line list provides a new opportunity to investigate these dependences, which is the goal of this work. First, we investigate how the toto line list affects observable transmission and emission spectra of hot Jupiters at low and high resolutions. The improvement in the toto line list compared to a previous line list results in observable differences in the model spectra, particularly in the optical at high resolution. Secondly, we explore the interplay between temperature structure, irradiation, and composition with TiO as the primary source of optical opacity, using 1D self-consistent atmospheric models. Among other trends, we find that the propensity for thermal inversions due to TiO peaks at C/O ∼ 0.9, consistent with recent studies. Using these models, we further assess metrics to quantify thermal inversions due to TiO, compared to frequently used Spitzer photometry, over a range in C/O, irradiation, metallicity, gravity, and stellar type.

scholarly journals A new set of atmosphere and evolution models for cool T–Y brown dwarfs and giant exoplanets

2020 ◽  
Vol 637 ◽  
pp. A38 ◽  
Author(s):  
M. W. Phillips ◽  
P. Tremblin ◽  
I. Baraffe ◽  
G. Chabrier ◽  
N. F. Allard ◽  
...  
Keyword(s):  
Near Infrared ◽  
Vertical Mixing ◽  
Emission Spectra ◽  
Brown Dwarfs ◽  
Atmospheric Temperature ◽  
Temperature Structure ◽  
Surface Boundary ◽  
Quantum Molecular Dynamics ◽  
Solar Metallicity ◽  
The Impact

We present a new set of solar metallicity atmosphere and evolutionary models for very cool brown dwarfs and self-luminous giant exoplanets, which we term ATMO 2020. Atmosphere models are generated with our state-of-the-art 1D radiative-convective equilibrium code ATMO, and are used as surface boundary conditions to calculate the interior structure and evolution of 0.001–0.075 M⊙ objects. Our models include several key improvements to the input physics used in previous models available in the literature. Most notably, the use of a new H–He equation of state including ab initio quantum molecular dynamics calculations has raised the mass by ~1−2% at the stellar–substellar boundary and has altered the cooling tracks around the hydrogen and deuterium burning minimum masses. A second key improvement concerns updated molecular opacities in our atmosphere model ATMO, which now contains significantly more line transitions required to accurately capture the opacity in these hot atmospheres. This leads to warmer atmospheric temperature structures, further changing the cooling curves and predicted emission spectra of substellar objects. We present significant improvement for the treatment of the collisionally broadened potassium resonance doublet, and highlight the importance of these lines in shaping the red-optical and near-infrared spectrum of brown dwarfs. We generate three different grids of model simulations, one using equilibrium chemistry and two using non-equilibrium chemistry due to vertical mixing, all three computed self-consistently with the pressure-temperature structure of the atmosphere. We show the impact of vertical mixing on emission spectra and in colour-magnitude diagrams, highlighting how the 3.5−5.5 μm flux window can be used to calibrate vertical mixing in cool T–Y spectral type objects.

Temperature structure in the upper 250 metres in the East Australian Current area

1968 ◽  
Vol 19 (2) ◽  
pp. 91 ◽  
Author(s):  
BV Hamon
Keyword(s):  
Mixed Layer ◽  
Small Area ◽  
Close Relation ◽  
Temperature Structure ◽  
East Australian Current ◽  
Temperature Profiles ◽  
Regression Equations ◽  
Wide Range ◽  
Current Area ◽  
Mixed Layers

Temperature profiles to 250 m, obtained by using a bathythermograph, are presented and discussed in relation to geostrophic currents in the East Australian Current Area. There is a very close relation between dynamic height and temperature at 240 m depth in this area. Regression equations connecting the two quantities are given. The depth of the mixed layer is shown to cover a wide range, even on a single cruise in a relatively small area, and it is suggested that the extremes of very shallow (< 20 m) and very deep (≥ 200 m) mixed layers are due to divergence and convergence associated with the strong and variable circulation in the area. Seasonal warming and cooling affect approximately the upper 70-100 m, and have a range of about 3�C.

Atmospheric vertical energy flux due to a ground disturbance

1969 ◽  
Vol 47 (7) ◽  
pp. 707-725 ◽  
Author(s):  
Robert F. MacKinnon
Keyword(s):  
Energy Flux ◽  
Acoustic Waves ◽  
Ionospheric Disturbances ◽  
Temperature Structure ◽  
Temperature Profiles ◽  
Perfect Gas ◽  
Small Oscillations ◽  
Leaky Modes ◽  
Discrete And Continuous Spectra ◽  
The Relationship

Evaluations are given of the nett mean vertical energy flux due to small oscillations at several altitudes caused by a ground disturbance in a wind- and temperature-stratified atmosphere. A theoretical model is assumed which consists of an inviscid perfect gas above a flat nonrotating earth. Results are given for various wind and temperature profiles. It is found that winds can appreciably affect the energy flux due to long-period waves at great heights. The importance of the temperature structure in the vicinity of critical levels is demonstrated. The significance of 'leaky' modes is discussed with regard to the relationship between the discrete and continuous spectra of waves. A simple approximation to energy flux associated with acoustic waves of short periods is found to apply for certain ground disturbances. The relevance of the results to traveling ionospheric disturbances is discussed.

scholarly journals Temperature structure and vertical mixing of water mass in mesocosms in Lake Suwa.

1989 ◽  
Vol 50 (4) ◽  
pp. 299-311 ◽  
Author(s):  
Motoaki KISHINO ◽  
Masayuki TAKAHASHI ◽  
Hidetake HAYASHI
Keyword(s):  
Water Mass ◽  
Vertical Mixing ◽  
Temperature Structure ◽  
Lake Suwa

Populations of phytoplankton in the western English Channel between 1964 and 1974

1981 ◽  
Vol 61 (3) ◽  
pp. 565-583 ◽  
Author(s):  
Linda Maddock ◽  
G. T. Boalch ◽  
D. S. Harbour
Keyword(s):  
Correspondence Analysis ◽  
Seasonal Pattern ◽  
Temperature Structure ◽  
English Channel ◽  
Species Succession ◽  
Quantitative Basis ◽  
Long Term Trends ◽  
Different Depths ◽  
Taxonomic Groups

Phytoplankton data collected between 1964 and 1974 at three stations in the western English Channel were analysed by the multivariate method of correspondence analysis. The data comprised counts, logarithmically transformed, of 126 taxonomic groups in 700 samples from different depths. The first three axes from the correspondence analysis explained only 17% of the total variation, but the sample positions on these axes showed a clear mean seasonal cycle, slightly different at each station. The species fell into ten groups according to their position on the axes and to their seasonal occurrence. Differences in the position on the axes of samples from different depths on the same occasion correlated well with the temperature structure of the water column. No clear long-term trends were apparent although there were obviously large differences from year to year. The results provide a mean seasonal pattern of species succession on a quantitative basis which can be used to compare counts from different areas or to identify changes in the same area.

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