VHF echoes from the midlatitude mesosphere and the thermal structure observed by lidar

Abstract Four one-dimensional models which have been used to characterize surface mixed layer (ML) processes and the thermal structure are described. Although most any model can be calibrated to mimic surface water temperatures, it does not imply that the corresponding mixing processes are well described. Eddy diffusion or "K" models can exhibit this problem. If a ML model is to be useful for water quality applications, then it must be able to resolve storm events and, therefore, be able to simulate the ML depth, h, and its time rate of change, dh/dt. A general water quality model is derived from mass conservation principles to demonstrate how ML models can be used in a physically meaningful way to address water quality issues.

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INVESTIGATING THE SEISMIC AND THERMAL STRUCTURE OF THE CIRCUM-ARCTIC LITHOSPHERE AND ASTHENOSPHERE

10.1130/abs/2017am-294988 ◽

2017 ◽

Author(s):

Andrew J. Schaeffer ◽

◽

Sergei Lebedev ◽

Javier Fullea ◽

Pascal Audet

Keyword(s):

Thermal Structure

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THE COMPOSITIONAL AND THERMAL STRUCTURE OF THE LITHOSPHERE AND UPPER MANTLE BENEATH THE SUPERIOR CRATON: RESULTS FROM MULTI-OBSERVABLE PROBABILISTIC INVERSION

10.1130/abs/2020am-353031 ◽

2020 ◽

Author(s):

Riddhi Dave ◽

◽

Fiona Darbyshire ◽

Juan Carlos Afonso ◽

Khaled Ali

Keyword(s):

Upper Mantle ◽

Thermal Structure ◽

Superior Craton ◽

Probabilistic Inversion

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Thermal squeezing of the seismogenic zone controlled rupture of the volcano-rooted Flores Thrust

Science Advances ◽

10.1126/sciadv.abe2348 ◽

2021 ◽

Vol 7 (5) ◽

pp. eabe2348

Author(s):

Karen Lythgoe ◽

Muzli Muzli ◽

Kyle Bradley ◽

Teng Wang ◽

Andri Dian Nugraha ◽

...

Keyword(s):

Thermal Structure ◽

Critical Role ◽

Volcanic Edifice ◽

Seismic Array ◽

Temperature Gradients ◽

Seismogenic Zone ◽

Arc Volcano

Temperature plays a critical role in defining the seismogenic zone, the area of the crust where earthquakes most commonly occur; however, thermal controls on fault ruptures are rarely observed directly. We used a rapidly deployed seismic array to monitor an unusual earthquake cascade in 2018 at Lombok, Indonesia, during which two magnitude 6.9 earthquakes with surprisingly different rupture characteristics nucleated beneath an active arc volcano. The thermal imprint of the volcano on the fault elevated the base of the seismogenic zone beneath the volcanic edifice by 8 km, while also reducing its width. This thermal “squeezing” directly controlled the location, directivity, dynamics, and magnitude of the earthquake cascade. Earthquake segmentation due to thermal structure can occur where strong temperature gradients exist on a fault.

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Urca nuclide production in Type-I X-ray bursts and implications for nuclear physics studies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3414 ◽

2020 ◽

Vol 500 (3) ◽

pp. 2958-2968

Author(s):

Grant Merz ◽

Zach Meisel

Keyword(s):

Light Curve ◽

Nuclear Reaction ◽

Nuclear Physics ◽

Thermal Structure ◽

Reaction Rates ◽

High Mass ◽

Type I ◽

Model Calculations ◽

X Ray ◽

Lower Temperature

ABSTRACT The thermal structure of accreting neutron stars is affected by the presence of urca nuclei in the neutron star crust. Nuclear isobars harbouring urca nuclides can be produced in the ashes of Type I X-ray bursts, but the details of their production have not yet been explored. Using the code MESA, we investigate urca nuclide production in a one-dimensional model of Type I X-ray bursts using astrophysical conditions thought to resemble the source GS 1826-24. We find that high-mass (A ≥ 55) urca nuclei are primarily produced late in the X-ray burst, during hydrogen-burning freeze-out that corresponds to the tail of the burst light curve. The ∼0.4–0.6 GK temperature relevant for the nucleosynthesis of these urca nuclides is much lower than the ∼1 GK temperature most relevant for X-ray burst light curve impacts by nuclear reaction rates involving high-mass nuclides. The latter temperature is often assumed for nuclear physics studies. Therefore, our findings alter the excitation energy range of interest in compound nuclei for nuclear physics studies of urca nuclide production. We demonstrate that for some cases this will need to be considered in planning for nuclear physics experiments. Additionally, we show that the lower temperature range for urca nuclide production explains why variations of some nuclear reaction rates in model calculations impacts the burst light curve but not local features of the burst ashes.

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Implications of GNSS-Inferred Tropopause Altitude Associated with Terrestrial Gamma-Ray Flashes

Remote Sensing ◽

10.3390/rs13101939 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1939

Author(s):

Tao Xian ◽

Gaopeng Lu ◽

Hongbo Zhang ◽

Yongping Wang ◽

Shaolin Xiong ◽

...

Keyword(s):

Gamma Ray ◽

Thermal Structure ◽

Deep Convection ◽

Caribbean Sea ◽

Negative Bias ◽

Upper Troposphere ◽

Cold Anomaly ◽

The Caribbean ◽

Geographic Distributions

The thermal structure of the environmental atmosphere associated with Terrestrial Gamma-ray Flashes (TGFs) is investigated with the combined observations from several detectors (FERMI, RHESSI, and Insight-HXMT) and GNSS-RO (SAC-C, COSMIC, GRACE, TerraSAR-X, and MetOp-A). The geographic distributions of TGF-related tropopause altitude and climatology are similar. The regional TGF-related tropopause altitude in Africa and the Caribbean Sea is 0.1–0.4 km lower than the climatology, whereas that in Asia is 0.1–0.2 km higher. Most of the TGF-related tropopause altitudes are slightly higher than the climatology, while some of them have a slightly negative bias. The subtropical TGF-producing thunderstorms are warmer in the troposphere and have a colder and higher tropopause over land than the ocean. There is no significant land–ocean difference in the thermal structure for the tropical TGF-producing thunderstorms. The TGF-producing thunderstorms have a cold anomaly in the middle and upper troposphere and have stronger anomalies than the deep convection found in previous studies.

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