The Experts below are selected from a list of 166443 Experts worldwide ranked by ideXlab platform
K Lorbacher - One of the best experts on this subject based on the ideXlab platform.
-
ocean mixed Layer Depth a subsurface proxy of ocean atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, Dietmar Dommenget, Pearn P Niiler, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (<5 m) and ±8 m for low- (<20 m) resolution profiles. A quality index, QImix, which compares the variance of a profile above h mix to the variance to a Depth of 1.5 × h mix, shows that for the 70% of the profile data for which a clearly recognizable well-mixed zone exists near the surface, our criterion identifies the Depth of the well-mixed zone in all cases. The standard deviation of anomalous monthly h mix/c is typically 20–70% of the long-term mean h mix/c . In the tropical Pacific the monthly mean anomalies of h mix/c are not well correlated with anomalies of sea surface temperature, which indicate that a variety of turbulent processes, other than surface heat fluxes, are important in the upper ocean there. Comparisons between observed h mix/c and Massachusetts Institute of Techonology/ocean general circulation model/Estimating the Circulation and Climate of the Ocean model simulated mixed Layer Depth indicate that the KPP algorithm captures in general a 30% smaller mixed Layer Depth than observed.
-
Ocean mixed Layer Depth: A subsurface proxy of ocean‐atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, Dietmar Dommenget, Pearn P Niiler, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (
-
Ocean mixed Layer Depth: A subsurface proxy of ocean-atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, P. P. Niiler, Dietmar Dommenget, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (
Armin Kohl - One of the best experts on this subject based on the ideXlab platform.
-
ocean mixed Layer Depth a subsurface proxy of ocean atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, Dietmar Dommenget, Pearn P Niiler, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (<5 m) and ±8 m for low- (<20 m) resolution profiles. A quality index, QImix, which compares the variance of a profile above h mix to the variance to a Depth of 1.5 × h mix, shows that for the 70% of the profile data for which a clearly recognizable well-mixed zone exists near the surface, our criterion identifies the Depth of the well-mixed zone in all cases. The standard deviation of anomalous monthly h mix/c is typically 20–70% of the long-term mean h mix/c . In the tropical Pacific the monthly mean anomalies of h mix/c are not well correlated with anomalies of sea surface temperature, which indicate that a variety of turbulent processes, other than surface heat fluxes, are important in the upper ocean there. Comparisons between observed h mix/c and Massachusetts Institute of Techonology/ocean general circulation model/Estimating the Circulation and Climate of the Ocean model simulated mixed Layer Depth indicate that the KPP algorithm captures in general a 30% smaller mixed Layer Depth than observed.
-
Ocean mixed Layer Depth: A subsurface proxy of ocean‐atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, Dietmar Dommenget, Pearn P Niiler, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (
-
Ocean mixed Layer Depth: A subsurface proxy of ocean-atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, P. P. Niiler, Dietmar Dommenget, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (
David Garciavizcaino - One of the best experts on this subject based on the ideXlab platform.
-
mixed Layer Depth determination in the barcelona coastal area from regular lidar measurements methods results and limitations
Boundary-Layer Meteorology, 2006Co-Authors: Michael Sicard, C Perez, Francesc Rocadenbosch, Jose Maria Baldasano, David GarciavizcainoAbstract:Regular aerosol backscatter measurements using an elastic-backscatter lidar were performed between May 2000 and December 2002 in Barcelona (Spain), within the framework of the European project EARLINET (European Aerosol Research Lidar Network). The mixed-Layer Depth was one of the major parameters to be retrieved. Three derivative methods have been tested in this complex coastal area using the range-squared-corrected lidar signal: (1) the minimum of its first derivative, (2) the minimum of its second derivative, and (3) the minimum of the first derivative of its logarithm. The second method was found to give statistically the best results when compared to radiosoundings, and was used to process the whole dataset. A number of 162 days and 660 profiles averaged over 30 min have been examined. Between 1000 and 1500 UTC, the mixed-Layer Depth oscillates between 300 and 1450 m in summer and between 390 and 1420 m in winter. The standard deviation for this portion of the day is 180 and 256 m, respectively, in summer and winter. In summer, low heights (mainly limited to 400–800 m) are associated with large mesoscale compensatory subsidence over the sea and to the thermal internal boundary-Layer formation. The strong coastal and orographic influences and the climatological settling of Barcelona determine the complexity of the boundary-Layer dynamics and the high heterogeneity of the lidar signals. In many cases, single lidar analyses do not allow an unambiguous determination of the mixed-Layer Depth. Two diurnal cycle measurements are discussed together with synoptic maps, backtrajectories and radiosoundings in order to outline the complexity of the area and the limitations of the methods.
Dietmar Dommenget - One of the best experts on this subject based on the ideXlab platform.
-
ocean mixed Layer Depth a subsurface proxy of ocean atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, Dietmar Dommenget, Pearn P Niiler, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (<5 m) and ±8 m for low- (<20 m) resolution profiles. A quality index, QImix, which compares the variance of a profile above h mix to the variance to a Depth of 1.5 × h mix, shows that for the 70% of the profile data for which a clearly recognizable well-mixed zone exists near the surface, our criterion identifies the Depth of the well-mixed zone in all cases. The standard deviation of anomalous monthly h mix/c is typically 20–70% of the long-term mean h mix/c . In the tropical Pacific the monthly mean anomalies of h mix/c are not well correlated with anomalies of sea surface temperature, which indicate that a variety of turbulent processes, other than surface heat fluxes, are important in the upper ocean there. Comparisons between observed h mix/c and Massachusetts Institute of Techonology/ocean general circulation model/Estimating the Circulation and Climate of the Ocean model simulated mixed Layer Depth indicate that the KPP algorithm captures in general a 30% smaller mixed Layer Depth than observed.
-
Ocean mixed Layer Depth: A subsurface proxy of ocean‐atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, Dietmar Dommenget, Pearn P Niiler, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (
-
Ocean mixed Layer Depth: A subsurface proxy of ocean-atmosphere variability
Journal of Geophysical Research, 2006Co-Authors: K Lorbacher, P. P. Niiler, Dietmar Dommenget, Armin KohlAbstract:A new criterion, based on the shallowest extreme curvature of near surface Layer density or temperature profiles, is established for demarking the mixed Layer Depth, h mix. Using historical global hydrographic profile data, including conductivity-temperature-Depth and expendable bathythermograph data obtained during World Ocean Circulation Experiment, its seasonal variability and monthly to interannual anomalies are computed. Unlike the more commonly used Δ criterion, the new criterion is able to deal with both different vertical resolutions of the data set and a large variety of observed stratification profiles. For about two thirds of the profiles our algorithm produces an h mix/c that is more reliable than the one of the Δ criterion. The uncertainty for h mix/c is ±5 m for high- (
M L Zoeteweij - One of the best experts on this subject based on the ideXlab platform.
-
Quasi-two-dimensional turbulence in shallow fluid Layers: the role of bottom friction and fluid Layer Depth.
Physical review. E Statistical nonlinear and soft matter physics, 2003Co-Authors: H J H Clercx, G J F Van Heijst, M L ZoeteweijAbstract:The role of bottom friction and the fluid Layer Depth in numerical simulations and experiments of freely decaying quasi-two-dimensional turbulence in shallow fluid Layers has been investigated. In particular, the power-law behavior of the compensated kinetic energy E0(t)=E(t)e(2lambda t), with E(t) the total kinetic energy of the flow and lambda the bottom-drag coefficient, and the compensated enstrophy Omega(0)(t)=Omega(t)e(2lambda t), with Omega(t) the total enstrophy of the flow, have been studied. We also report on the scaling exponents of the ratio Omega(t)/E(t), which is considered as a measure of the characteristic length scale in the flow, for different values of lambda. The numerical simulations on square bounded domains with no-slip boundaries revealed bottom-friction independent power-law exponents for E0(t), Omega(0)(t), and Omega(t)/E(t). By applying a discrete wavelet packet transform technique to the numerical data, we have been able to compute the power-law exponents of the average number density of vortices rho(t), the average vortex radius a(t), the mean vortex separation r(t), and the averaged normalized vorticity extremum omega(ext)(t)/square root E(t). These decay exponents proved to be independent of the bottom friction as well. In the experiments we have varied the fluid Layer Depth, and it was found that the decay exponents of E0(t), Omega(0)(t), Omega(t)/E(t), and omega(ext)(t)/square root E(t) are virtually independent of the fluid Layer Depth. The experimental data for rho(t) and a(t) are less conclusive; power-law exponents obtained for small fluid Layer Depths agree with those from previously reported experiments, but significantly larger power-law exponents are found for experiments with larger fluid Layer Depths.
-
Quasi-two-dimensional turbulence in shallow fluid Layers: the role of bottom friction and fluid Layer Depth.
Physical Review E, 2003Co-Authors: H J H Clercx, Van Gjf Gert-jan Heijst, M L ZoeteweijAbstract:The role of bottom friction and the fluid Layer Depth in numerical simulations and experiments of freely decaying quasi-two-dimensional turbulence in shallow fluid Layers has been investigated. In particular, the power-law behavior of the compensated kinetic energy ${E}_{0}{(t)=E(t)e}^{2\ensuremath{\lambda}t},$ with $E(t)$ the total kinetic energy of the flow and $\ensuremath{\lambda}$ the bottom-drag coefficient, and the compensated enstrophy ${\ensuremath{\Omega}}_{0}(t)=\ensuremath{\Omega}(t){\mathrm{e}}^{2\ensuremath{\lambda}t},$ with $\ensuremath{\Omega}(t)$ the total enstrophy of the flow, have been studied. We also report on the scaling exponents of the ratio $\ensuremath{\Omega}(t)/E(t),$ which is considered as a measure of the characteristic length scale in the flow, for different values of $\ensuremath{\lambda}.$ The numerical simulations on square bounded domains with no-slip boundaries revealed bottom-friction independent power-law exponents for ${E}_{0}(t),$ ${\ensuremath{\Omega}}_{0}(t),$ and $\ensuremath{\Omega}(t)/E(t).$ By applying a discrete wavelet packet transform technique to the numerical data, we have been able to compute the power-law exponents of the average number density of vortices $\ensuremath{\rho}(t),$ the average vortex radius $a(t),$ the mean vortex separation $r(t),$ and the averaged normalized vorticity extremum ${\ensuremath{\omega}}_{\mathrm{ext}}(t)/\sqrt{E(t)}.$ These decay exponents proved to be independent of the bottom friction as well. In the experiments we have varied the fluid Layer Depth, and it was found that the decay exponents of ${E}_{0}(t),$ ${\ensuremath{\Omega}}_{0}(t),$ $\ensuremath{\Omega}(t)/E(t),$ and ${\ensuremath{\omega}}_{\mathrm{ext}}(t)/\sqrt{E(t)}$ are virtually independent of the fluid Layer Depth. The experimental data for $\ensuremath{\rho}(t)$ and $a(t)$ are less conclusive; power-law exponents obtained for small fluid Layer Depths agree with those from previously reported experiments, but significantly larger power-law exponents are found for experiments with larger fluid Layer Depths.