Improved Internal Wave Spectral Continuum in a Regional Ocean Model

Recent work demonstrates that high‐resolution global models forced simultaneously by atmospheric fields and the astronomical tidal potential contain a partial internal (gravity) wave (IW) spectral continuum. Regional simulations of the MITgcm forced at the horizontal boundaries by a global run that carries a partial IW continuum spectrum are performed at the same grid spacing as the global run and at finer grid spacings in an attempt to fill out more of the IW spectral continuum. Decreasing only the horizontal grid spacing from 2 to 0.25 km greatly improves the frequency spectra and slightly improves the vertical wavenumber spectra of the horizontal velocity. Decreasing only the vertical grid spacing by a factor of 3 does not yield any significant improvements. Decreasing both horizontal and vertical grid spacings yields the greatest degree of improvement, filling the frequency spectrum out to 72 cpd. Our results suggest that improved IW spectra in regional models are possible if they are run at finer grid spacings and are forced at their lateral boundaries by remotely generated IWs. Additionally, consistency relations demonstrate that improvements in the spectra are indeed due to the existence of IWs at higher frequencies and vertical wavenumbers when remote IW forcing is included and model grid spacings decrease. By being able to simulate an IW spectral continuum to 0.25 km scales, these simulations demonstrate that one may be able to track the energy pathways of IWs from generation to dissipation and improve the understanding of processes such as IW‐driven mixing.Plain Language SummaryModels of internal waves (IWs) may help us to better understand the spatial geography of mixing in the ocean and are playing an increasingly important role in the planning of satellite missions. Following recent work showing that high‐resolution global models contain a partial IW spectrum, this paper describes further improvements in the spectrum seen in a high‐resolution regional model forced at the boundaries by a previously performed global IW simulation. Decreasing only the horizontal grid spacing greatly improves the frequency spectra and slightly improves the vertical wavenumber spectra of velocity. Increasing only the number of vertical levels does not yield any significant improvements. Decreasing both horizontal and vertical grid spacings yields the greatest improvement in both spectra. Our results suggest that regional models can exhibit improved IW spectra over global models if two conditions are met—they must have higher horizontal and vertical resolutions, and they must have remotely generated IWs at their boundaries. Application of the so‐called consistency relations demonstrates that the model is indeed carrying a field of high‐frequency IWs. Being able to simulate a fuller IW spectrum demonstrates that one may be able to use these models to improve the understanding of IW‐driven processes and energy pathways.Key PointsInternal gravity wave spectra in regional models are more realistic as model grid spacing decreasesThe vertical wavenumber spectra improve less dramatically than the frequency spectraInternal gravity wave consistency relations are applied to modeled spectraPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154917/1/jgrc23947_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154917/2/jgrc23947.pd

Glycogen Synthase Kinase (GSK) 3β phosphorylates and protects nuclear myosin 1c from proteasome-mediated degradation to activate rDNA transcription in early G1 cells

Nuclear myosin 1c (NM1) mediates RNA polymerase I (pol I) transcription activation and cell cycle progression by facilitating PCAF-mediated H3K9 acetylation, but the molecular mechanism by which NM1 is regulated remains unclear. Here, we report that at early G1 the glycogen synthase kinase (GSK) 3β phosphorylates and stabilizes NM1, allowing for NM1 association with the chromatin. Genomic analysis by ChIP-Seq showed that this mechanism occurs on the rDNA as active GSK3β selectively occupies the gene. ChIP assays and transmission electron microscopy in GSK3β-/- mouse embryonic fibroblasts indicated that at G1 rRNA synthesis is suppressed due to decreased H3K9 acetylation leading to a chromatin state incompatible with transcription. We found that GSK3β directly phosphorylates the endogenous NM1 on a single serine residue (Ser-1020) located within the NM1 C-terminus. In G1 this phosphorylation event stabilizes NM1 and prevents NM1 polyubiquitination by the E3 ligase UBR5 and proteasome-mediated degradation. We conclude that GSK3β-mediated phosphorylation of NM1 is required for pol I transcription activation

Serine Protease PRSS23 Is Upregulated by Estrogen Receptor α and Associated with Proliferation of Breast Cancer Cells

Serine protease PRSS23 is a newly discovered protein that has been associated with tumor progression in various types of cancers. Interestingly, PRSS23 is coexpressed with estrogen receptor α (ERα), which is a prominent biomarker and therapeutic target for human breast cancer. Estrogen signaling through ERα is also known to affect cell proliferation, apoptosis, and survival, which promotes tumorigenesis by regulating the production of numerous downstream effector proteins

Comparison of laboratory and numerically observed scalar fields of an internal wave attractor

Observations of internal gravity wave beams are frequently accompanied by theory that is purely two-dimensional, or two-dimensional numerical models. Although qualitative agreement between such models and laboratory experiments has been demonstrated, quantitative comparison has only been possible in a limited range of cases. Here, we present a quantitative comparison for internal wave attractors in the laboratory and a two-dimensional non-hydrostatic numerical model. To make a closer connection with previous theoretical work, the experimental and numerical results are presented in terms of the streamfunction and density perturbation, rather than the measured velocity and density gradient fields. The streamfunction is commonly used in the two-dimensional descriptions, e.g. to predict spatial patterns found in an enclosed stratified fluid in the laboratory. We demonstrate that, although the laboratory experiment in a narrow tank is only semi-two-dimensional, the flow is well described by two-dimensional internal wave theory and the numerical model reproduces quantitatively comparable attractors. The observed streamfunction field is compared with theoretical predictions, addressing an open question on the form of the streamfunction for internal wave attractor in a trapezoidal domain. The streamfunction has a simple spatial structure with sharp gradients at the attractor separating regions of nearly constant value outside the attractor

Large-amplitude internal tides, solitary waves, and turbulence in the central Bay of Biscay

International audienceMicrostructure and fine-scale measurements collected in the central Bay of Biscay during the MOUTON experiment are analyzed to investigate the dynamics of internal waves and associated mixing. Large-amplitude internal tides (ITs) that excite internal solitary waves (ISWs) in the thermocline are observed. ITs are dominated by modes 3 and 4, while ISWs projected on mode 1 that is trapped in the thermocline. Therein, ITs generate a persistent narrow shear band, which is strongly correlated with the enhanced dissipation rate in the thermocline. This strong dissipation rate is further reinforced in the presence of ISWs. Dissipation rates during the period without ISWs largely agree with the MacKinnon-Gregg scaling proposed for internal wavefields dominated by a low-frequency mode, while they show poor agreement with the Gregg-Henyey parameterization valid for internal wavefields close to the Garrett-Munk model. The agreement with the MacKinnon-Gregg scaling is consistent with the fact that turbulent mixing here is driven by the low-frequency internal tidal shear