Seminal Evidence of a 2.5-Sol Ultra-Fast Kelvin Wave in Mars’ Middle and Upper Atmosphere

The structure and dynamics of Mars\u27 middle and upper atmosphere is significantly impacted by waves propagating from the lower atmosphere. Using concurrent temperature and neutral density measurements taken by the Mars Reconnaissance Orbiter and Mars Atmosphere and Volatile EvolutioN satellites, we demonstrate for the first time that a 2.5‐sol ultra‐fast Kelvin wave is a prominent global‐scale feature of the low‐latitude middle (i.e., 30–80 km) and upper (approximately 150 km) atmosphere of Mars. Further, we present evidence of secondary waves arising from nonlinear interactions between this ultra‐fast Kelvin wave and solar tides, and based on their amplitudes we surmise that they could represent an important source of tidal and longitudinal variability in the aerobraking region

Exploring Wave-Wave Interactions in a General Circulation Model

Nonlinear interactions involving Kelvin waves with (periods, zonal wave numbers) = (3.7d, s =− 1) (UFKW1) and = (2.4d, s =− 1) (UFKW2) and s = 0 and s = 1 quasi 9 day waves (Q9DW) with diurnal tides DW1, DW2, DW3, DE2, and DE3 are explored within a National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-mesosphere electrodynamics general circulation model (TIME-GCM) simulation driven at its ∼30 km lower boundary by interpolated 3-hourly output from Modern-Era Retrospective Analysis for Research and Applications (MERRA). The existence of nonlinear wave-wave interactions between the above primary waves is determined by the presence of secondary waves (SWs) with frequencies and zonal wave numbers that are the sums and differences of those of the primary (interacting) waves. Focus is on 10–21 April 2009, when the nontidal dynamics in the mesosphere-lower thermosphere (MLT) region is dominated by UFKW and when identification of SW is robust. Fifteen SWs are identified in all. An interesting triad is identified involving UFKW1, DE3, and a secondary UFKW4 = (1.5d, s =− 2): The UFKW1-DE3 interaction produces UFKW4, the UFKW4-DE3 interaction produces UFKW1, and the UFKW1 interaction with UFKW4 produces DE3. At 120 km the dynamic range of the reconstructed latitude-longitude zonal wind field due to all of the SW is roughly half that of the primary waves, which produced them. This suggests that nonlinear wave-wave interactions could significantly modify the way that the lower atmosphere couples with the ionosphere

Rossby wave second harmonic generation observed in the middle atmosphere

Second harmonic generation is the lowest-order wave-wave nonlinear interaction occurring in, e.g., optical, radio, and magnetohydrodynamic systems. As a prototype behavior of waves, second harmonic generation is used broadly, e.g., for doubling Laser frequency. Second harmonic generation of Rossby waves has long been believed to be a mechanism of high-frequency Rossby wave generation via cascade from low-frequency waves. Here, we report the observation of a Rossby wave second harmonic generation event in the atmosphere. We diagnose signatures of two transient waves at periods of 16 and 8 days in the terrestrial middle atmosphere, using meteor-radar wind observations over the European and Asian sectors during winter 2018&ndash;2019. Their temporal evolution, frequency and wavenumber relations, and phase couplings revealed by bicoherence and biphase analyses demonstrate that the 16-day signature is an atmospheric manifestation of a Rossby wave normal mode, and its second harmonic generation gives rise to the 8-day signature. Our finding confirms the theoretically-anticipated Rossby wave nonlinearity. &nbsp;</p

Global Scale Wave Model 2009 (GSWM-09)

GSWM-09 results provide the most recent comprehensive set of GSWM outputs that provide amplitudes and phases (UT of maximum at 0&ordm; longitude) of solar diurnal and semidiurnal tidal wind and temperature perturbations in Earth's atmosphere from pole to pole and from the ground to 245 km altitude. Their value lies in the use of realistic observational and empirical model data to specify the tropospheric and stratospheric forcing of the full spectrum of solarsynchronous ("migrating" with the Sun) and solar-asynchronous ("non-migrating") components of the tidal spectrum, along with diurnal mean winds and temperatures. Notably, GSWM-09 does not include tidal sources known to exist in the thermosphere above approximately 120 km altitude. GSWM-09 results are mainly intended 1) as a resource for the global array of ground-based radar and active and passive optical remote-sensing instruments that measure the dynamics of the atmosphere below about 110 km altitude, 2) for forcing the lower boundaries of thermosphere-ionosphere general circulation models, and 3) for the extrapolation of tidal structures to latitudes and heights where data are not available. GSWM-09 was created as part of the dissertation research of Dr. Xiaoli Zhang in the Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado at Boulder, in 2009: Zhang, Xiaoli (2010). Atmospheric Tides Forced by Troposphere Heating: Longitudinal Variability of Upper Atmosphere Consequences, A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Aerospace Engineering Sciences.&nbsp;https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/h128ng01b and subsequently published in the open literature: Zhang, X., J.M. Forbes, and M.E. Hagan (2010) Longitudinal variation of tides in the MLT region: 1. Tides driven by tropospheric net radiative heating, Journal of Geophysical Research, Space Physics, 115, A06316. doi:10.1029/2009JA014897 Zhang, X. , J.M. Forbes, and M.E. Hagan (2010). Longitudinal variation of tides in the MLT region: 2. Relative effects of solar radiative and latent heating, Journal of Geophysical Research, Space Physics, 115, A06317. doi:10.1029/2009JA014898 GSWM-09 follows on a series of earlier versions of the GSWM (e.g., Hagan and Forbes, 2002, 2003). The above Zhang et al. (2010) print publications are linked from this data repository, and include details about the GSWM, along with extensive references to earlier publications and earlier versions of the model, including Hagan and Forbes (2002, 2003). Also appended here are copies of tutorial-level descriptions of these earlier versions of the GSWM, with the list of references, that were previously archived in the now obsolete National Center for Atmospheric Research High Altitude Observatory (NCAR HAO) GSWM web site.</p

Mesospheric Q2DW Interactions With Four Migrating Tides at 53°N Latitude: Zonal Wavenumber Identification Through Dual‐Station Approaches

Mesospheric winds from two longitudinal sectors at 53°N latitude are combined to investigate quasi-two-day waves (Q2DWs) and their nonlinear interactions with tides. In a summer 2019 case study, we diagnose the zonal wavenumber m of spectral peaks at expected frequencies through two dual-station approaches, a phase differencing technique (PDT) on individual spectral peaks and a least squares procedure on family batched peaks. Consistent results from the approaches verify the occurrences of Rossby-gravity modes (m = 3 and 4 at periods T = 2.1 and 1.7 days), and their secondary waves (SWs) generated from interactions with diurnal, semi-diurnal, ter-diurnal, and quatra-diurnal migrating tides. We further extend the PDT to 2012–2019, illustrating that Q2DWs exhibit significant interannual variability. Composite analysis reveals seasonal and altitude variations of the Rossby-gravity modes and their SWs. The Rossby-gravity modes maximize in local summer, whereas their 16- and 9.6-h SWs appear more in winter

A novel estrus-synchronization program for anestrous and cycling, suckled, beef cows

We used four herds at three Kansas ranches to evaluate the potential of two new estrus synchronization strategies to increase estrus expression and fertility of 911 crossbred suckled beef cows. The treatments included: 1) 100 μg of GnRH and a 6-mg norgestomet ear implant on day -7 and 25 mg of PG F2" and implant removal on day 0 (GnRH+NORG+PG F2"); 2) 100 μg of GnRH on day - 7 and 25 mg of PGF 2" on day 0 (GnRH+PG F2"); and 3 ) (control) 25- mg injections of PG F2" on days -14 and 0; (2×PGF2" control) . The GnRH+NORG+ PGF 2" and GnRH+PGF treatments increased (P<.01) 2" the overall percentages of cows detected in estrus by 49% and 27% and pregnancy rates by 46% and 37%, respectively, over the control group, without altering conception rate. Both treatments increase d the estrus, conception, and pregnancy rates of noncycling cows, compared to controls

High-Order Solar Migrating Tides Quench at SSW Onsets

Sudden stratospheric warming events (SSWs) are the most spectacular atmospheric vertical coupling processes, well-known for being associated with diverse wave activities in the upper atmosphere and ionosphere. The first four solar tidal harmonics have been reported as being engaged. Here, combining mesospheric winds detected by three midlatitude radars, we demonstrate at least the first six harmonics that occurred during SSW 2018. Wave number diagnosis demonstrates that all six harmonics are dominated by migrating components. Wavelet analyses reveal that the fourth, fifth, and sixth harmonics quench after the SSW onset. The six harmonics and the quenching appear also in a statistical analysis based on near-12-year observations from one of the radars. We attribute the quenching to reversal of the background eastward wind. ©2020. The Authors

A gas-rich nuclear bar fuelling a powerful central starburst in NGC 2782

We present evidence that the peculiar interacting starburst galaxy NGC 2782 (Arp 215) harbors a gas-rich nuclear stellar bar feeding an M82-class powerful central starburst, from a study based on OVRO CO (J=1->0) data, WIYN BVR & Halpha observations, along with available NIR images, a 5 GHz RC map and HST images. NGC 2782 harbors a clumpy, bar-like CO feature of radius ~ 7.5'' (1.3 kpc) which leads a nuclear stellar bar of similar size. The nuclear CO bar is massive: it contains ~2.5x10**9 M_sun of molecular gas, which makes up ~ 8 % of the dynamical'mass present within a 1.3 kpc radius. Within the CO bar, emission peaks in two extended clumpy lobes which lie on opposite sides of the nucleus, separated by ~ 6'' (1 kpc). Between the CO lobes, in the inner 200 pc radius, resides a powerful central starburst which is forming stars at a rate of 3 to 6 M_sun yr-1. While circular motions dominate the CO velocity field, the CO lobes show weak bar-like streaming motions on the leading side of the nuclear stellar bar, suggestive of gas inflow. We estimate semi-analytically the gravitational torque from the nuclear stellar bar on the gas, and suggest large gas inflow rates from the CO lobes into the central starburst. These observations, which are amongst the first ones showing a nuclear stellar bar fuelling molecular gas into an intense central starburst, are consistent with simulations and theory which suggest that nuclear bars provide an efficient way of transporting gas closer to the galactic center to fuel central activity. Furthermore, several massive clumps are present at low radii, and dynamical friction might produce further gas inflow. We suggest that the nuclear molecular gas bas and central activity will be very short-lived, likely disappearing within 5x10**8 years.Comment: Accepted by the Astrophysical Journal, 10 pages, Latex with emulateapj.sty, apjfonts.sty, 10 postscript & 2 gif figure

Bilateral branch pulmonary artery valve implantation in repaired tetralogy of fallot

BackgroundTranscatheter, bilateral branch pulmonary artery (PA) valve implantation is a novel treatment for patients with severe pulmonary insufficiency and oversized right ventricle (RV) outflow tract. There is scarce data on efficacy and safety of this approach.MethodsThis was a retrospective study of 8 patients with repaired tetralogy of fallot (TOF) who underwent bilateral branch PA valve implantation. Demographics, echocardiography, cardiac catheterization, and axial imaging data were reviewed. Variables were compared by a paired sample t‐test.ResultsAll patients were adult sized (weight 43–99 kg) with oversized RV outflow tract not suitable for conventional transcatheter pulmonary valve implantation. Staged bare metal PA stenting followed by valve implantation (interval 3–5 months) was technically successful in 7 patients with one stent embolization. In another patient, proximal stent migration prevented placement of bilateral pulmonary valve stents. There were a total of 14 valved branch PA stents placed (Melody valve n = 9, Sapien XT n = 2, Sapien 3 n = 3). In the 7 patients undergoing successful branch pulmonary valve placement, at median follow up of 10 months (range 3 months to 6 years), 13 (93%) valves had none/trivial insufficiency on echocardiography. Prevalve and postvalve implantation cardiac magnetic resonance imaging in five patients showed significant reduction of indexed RV end‐diastolic volume (152 ± 27 to 105 ± 15 mL/m2, P < .001).ConclusionsTranscatheter, bilateral branch PA valve implantation was technically feasible with satisfactory efficacy and safety in patients with repaired TOF, severe pulmonary insufficiency, and oversized RV outflow tracts. Elimination of pulmonary insufficiency with this method resulted in reduced RV end‐diastolic volume. This approach can be offered as an alternative to surgery, particularly in patients considered high risk for standard surgical placement and who are not candidates for the newer self‐expanding valve prosthesis for placement in RV outflow tracts larger than 30 mm diameter.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143803/1/ccd27489.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143803/2/ccd27489_am.pd

On the Specification of Upward-Propagating Tides for ICON Science Investigations.

The National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) will provide a physics-based context for the interpretation of ICON measurements. To optimize the realism of the model simulations, ICON wind and temperature measurements near the ~97 km lower boundary of the TIEGCM will be used to specify the upward-propagating tidal spectrum at this altitude. This will be done by fitting a set of basis functions called Hough Mode Extensions (HMEs) to 27-day mean tidal winds and temperatures between 90 and 105 km altitude and between 12°S and 42°N latitude on a day-by-day basis. The current paper assesses the veracity of the HME fitting methodology given the restricted latitude sampling and the UT-longitude sampling afforded by the MIGHTI instrument viewing from the ICON satellite, which will be in a circular 27° inclination orbit. These issues are investigated using the output from a reanalysis-driven global circulation model, which contains realistic variability of the important tidal components, as a mock data set. ICON sampling of the model reveals that the 27-day mean diurnal and semidiurnal tidal components replicate well the 27-day mean tidal components obtained from full synoptic sampling of the model, but the terdiurnal tidal components are not faithfully reproduced. It is also demonstrated that reconstructed tidal components based on HME fitting to the model tides between 12°S and 42°N latitude provide good approximations to the major tidal components expected to be encountered during the ICON mission. This is because the constraints provided by fitting both winds and temperatures over the 90-105 km height range are adequate to offset the restricted sampling in latitude. The boundary conditions provided by the methodology described herein will greatly enhance the ability of the TIEGCM to provide a physical framework for interpreting atmosphere-ionosphere coupling in ICON observations due to atmospheric tides