4,171 research outputs found
Dataset of characteristic remanent magnetization and magnetic properties of early Pliocene sediments from IODP Site U1467 (Maldives platform)
This data article describes data of magnetic stratigraphy and anisotropy of isothermal remanent magnetization (AIRM) from "Magnetic properties of early Pliocene sediments from IODP Site U1467 (Maldives platform) reveal changes in the monsoon system" [1]. Acquisition of isothermal magnetization on pilot samples and anisotropy of isothermal remanent magnetization are reported as raw data; magnetostratigraphic data are reported as characteristic magnetization (ChRM).info:eu-repo/semantics/publishedVersio
Nonequilibrium thermodynamics of circulation regimes in optically-thin, dry atmospheres
An extensive analysis of an optically-thin, dry atmosphere at different
values of the thermal Rossby number Ro and of the Taylor number Ff is per-
formed with a general circulation model by varying the rotation rate {\Omega}
and the surface drag {\tau} in a wide parametric range. By using nonequilibrium
thermodynamics diagnostics such as material entropy production, efficiency,
meridional heat transport and kinetic energy dissipation we characterize in a
new way the different circulation regimes. Baroclinic circulations feature high
mechanical dissipation, meridional heat transport, material entropy pro-
duction and are fairly efficient in converting heat into mechanical work. The
thermal dissipation associated with the sensible heat flux is found to depend
mainly on the surface properties, almost independent from the rotation rate and
very low for quasi-barotropic circulations and regimes approaching equa- torial
super-rotation. Slowly rotating, axisymmetric circulations have the highest
meridional heat transport. At high rotation rates and intermediate- high drag,
atmospheric circulations are zonostrohic with very low mechanical dissipation,
meridional heat transport and efficiency. When {\tau} is interpreted as a
tunable parameter associated with the turbulent boundary layer trans- fer of
momentum and sensible heat, our results confirm the possibility of using the
Maximum Entropy Production Principle as a tuning guideline in the range of
values of {\Omega}. This study suggests the effectiveness of using fun-
damental nonequilibrium thermodynamics for investigating the properties of
planetary atmospheres and extends our knowledge of the thermodynamics of the
atmospheric circulation regimes
A direct helicopter EM sea ice thickness inversion, assessed with synthetic and field data
Accuracy and precision of helicopter electromagneticHEM sounding are the essential parameters for HEM seaicethickness profiling. For sea-ice thickness research, thequality of HEM ice thickness estimates must be better than10 cm to detect potential climatologic thickness changes.Weintroduce and assess a direct, 1D HEM data inversion algorithmfor estimating sea-ice thickness. For synthetic qualityassessment, an analytically determined HEM sea-ice thicknesssensitivity is used to derive precision and accuracy. Precisionis related directly to random, instrumental noise, althoughaccuracy is defined by systematic bias arising fromthe data processing algorithm. For the in-phase component ofthe HEM response, sensitivity increases with frequency andcoil spacing, but decreases with flying height. For small-scaleHEM instruments used in sea-ice thickness surveys, instrumentalnoise must not exceed 5 ppm to reach ice thicknessprecision of 10 cm at 15-m nominal flying height. Comparableprecision is yielded at 30-m height for conventional explorationHEM systems with bigger coil spacings. Accuracylosses caused by approximations made for the direct inversionare negligible for brackish water and remain better than10 cm for saline water. Synthetic precision and accuracy estimatesare verified with drill-hole validated field data fromEast Antarctica, where HEM-derived level-ice thicknessagrees with drilling results to within 4%, or 2 cm
- …