Annular variability and eddy-zonal flow interactions in a simplified atmospheric GCM. Part 1: Characterization of high and low frequency behaviour

Experiments have been performed using a simplified, Newtonian forced, global circulation model to investigate how variability of the tropospheric jet can be characterized by examining the combined fluctuations of the two leading modes of annular variability. Eddy forcing of this variability is analyzed in the phase space of the leading modes using the vertically integrated momentum budget. The nature of the annular variability and eddy forcing depends on the time scale. At low frequencies the zonal flow and baroclinic eddies are in quasi equilibrium and anomalies propagate poleward. The eddies are shown primarily to reinforce the anomalous state and are closely balanced by the linear damping, leaving slow evolution as a residual. At high frequencies the flow is strongly evolving and anomalies are initiated on the poleward side of the tropospheric jet and propagate equatorward. The eddies are shown to drive this evolution strongly: eddy location and amplitude reflect the past baroclinicity, while eddy feedback on the zonal flow may be interpreted in terms of wave breaking associated with baroclinic life cycles in lateral shear

LGBTQ Community College Students’ Decreased Sense of Belonging

LGBTQ students experience a lower sense of belonging at community colleges. The correlation between campus and classroom climate and academic success, campus involvement, identity, level of outness, and well-being for LGBTQ students contributes to their decreased sense of belonging. Non-LGBTQ-affirming and non-inclusive community college campuses and classrooms lead to feelings of fear, invisibility, lack of validation, mental health challenges, and poor academic performance for LGBTQ students. An extensive literature review was conducted to determine the root causes around the decreased sense of belonging for LGBTQ students enrolled at community colleges.  Three themes emerged that explained this decreased sense of belonging: heteronormative and cisnormative campus and classroom climates; a lack of LGBTQ-specific training for administrators, faculty, and staff; and a lack of LGBTQ-specific programming and services on campus. Creating a campus-wide administrator, faculty, staff, and student LGBTQ Task Force and promoting the affirmation, inclusion, safety, and visibility of LGBTQ students may help ameliorate the diminished sense of belonging experienced by LGBTQ students on community college campuses

Determinants of the demand for regular farm labour in South Africa, 1960-2002

This paper estimates long-run price (wage) elasticities of demand for regular farm labour in South Africa using both Ordinary Least Squares (OLS) regression and a Two-stage Least Squares (2SLS) simultaneous-equation model for the period 1960-2002. Both models include a piecewise interactive slope dummy variable with 1991 as the threshold year to reflect South African (SA) commercial farmers’ expectations that farm labour costs would increase as new labour legislation was introduced from the early 1990s onwards. The long-run price (wage) elasticity of demand for regular farm labour in South Africa during 1960-1990 was estimated as -0.25 for OLS and -0.23 for 2SLS regression, respectively. For the period 1991-2002, this elasticity estimate rose to -1.32 and -1.34 for OLS and 2SLS regression, respectively. These results suggest that a marked structural decline in the demand for regular labour has occurred since 1991 that raises questions about the appropriateness of labour laws and minimum wage legislation that have increased the cost of regular farm labour in South Africa.Regular farm labour, SA agriculture, price (wage) elasticities of demand, Farm Management, Labor and Human Capital,

No-till Forage Establishment in Alaska

We assessed the effectiveness of no-till forage establishment at six Alaska locations: Anchor Point, Sterling, Point MacKenzie, Palmer, Delta Junction, and Fairbanks. Directly seeding grass into established grass stands generally did not improve forage yields or quality. Seeding rate had little effect on establishment of newly seeded forages in no-till. Grass yields were depressed when companion crop yields were high, and they typically did not recover in subsequent years. Red clover established well, producing high yields of good quality forage under no-till at Point MacKenzie, but established poorly at Anchor Point and Delta Junction. These results indicated that no-till seeding of most forage crops into declining grass stands is not likely to be successful in Alaska with current available technology

Frontal Structure of the Antarctic Circumpolar Current in the South Indian Ocean

Using recently published atlas data [Olbers et al., 1992] and the Fine Resolution Antarctic Model (FRAM) [Webb et al., 1991], an investigation has been conducted into the structure of the frontal jets centered around the region of the islands of Crozet (46°27'S, 52°0'E) and Kerguelen (48°15'S, 69°10'E) in the south Indian Ocean. Geostrophic current velocities and transports were calculated from the temperature and salinity fields available from the atlas and compared with results from FRAM and previous studies. We have identified the Agulhas Return Front (ARF) and the Subtropical Front (STF), as well as the following fronts of the Antarctic Circumpolar Current (ACC): the Subantarctic Front (SAP), the Polar Front (PF), and the Southern ACC Front (SACCF), from temperature and salinity characteristics and from geostrophic currents. This analysis of model and atlas data indicates that the jets associated with the ARF, STF, and SAF are topograpliically steered into a unique frontal system north of the islands, having some of the largest temperature and salinity gradients anywhere in the world ocean. The frontal jet associated with the ARF is detectable up to 75°E and has associated with it several northward branching jets. The PF bifurcates in the region of the Ob'Lena (Conrad) seamount; subsurface and surface expressions are identified, separated by as much as 8° of latitude immediately west of the Kerguelen Plateau. The surface expression, carrying the bulk of the transport (~65 Sv), is steered through the col in the Kerguelen Plateau at 56°S, 6° south of the latitude normally associated with the PF at this meridian. On crossing the plateau it rejoins the subsurface expression. In the south, passing eastward along the margin of the Antarctic continent and through the Princess Elizabeth Trough, a frontal jet is identified transporting up to 35 Sv, believed to be the SACCF [Orsi et al., 1995], placing the southern extent of the ACC in the region at 67°S. Copyright 1996 by the American Geophysical Union

The impact of the state of the troposphere on the response to stratospheric heating in a simplified GCM

Previous studies have made use of simplified general circulation models (sGCMs) to investigate the atmospheric response to various forcings. In particular, several studies have investigated the tropospheric response to changes in stratospheric temperature. This is potentially relevant for many climate forcings. Here the impact of changing the tropospheric climatology on the modeled response to perturbations in stratospheric temperature is investigated by the introduction of topography into the model and altering the tropospheric jet structure. The results highlight the need for very long integrations so as to determine accurately the magnitude of response. It is found that introducing topography into the model and thus removing the zonally symmetric nature of the model’s boundary conditions reduces the magnitude of response to stratospheric heating. However, this reduction is of comparable size to the variability in the magnitude of response between different ensemble members of the same 5000-day experiment. Investigations into the impact of varying tropospheric jet structure reveal a trend with lower-latitude/narrower jets having a much larger magnitude response to stratospheric heating than higher-latitude/wider jets. The jet structures that respond more strongly to stratospheric heating also exhibit longer time scale variability in their control run simulations, consistent with the idea that a feedback between the eddies and the mean flow is both responsible for the persistence of the control run variability and important in producing the tropospheric response to stratospheric temperature perturbations

Simple guide to starting a research group

Conducting cutting-edge research and scholarship becomes more complicated with each passing year; forming a collaborative research group offers a way to navigate this increasing complexity. Yet many individuals whose work might benefit from the formation of a collaborative team may feel overwhelmed by the prospect of attempting to build and maintain a research group. We propose this simple guide for starting and maintaining such an enterprise

The antlions of Cyprus: review and new reports (Neuroptera: Myrmeleontidae)

The antlions (Myrmeleontidae) of Cyprus have been poorly studied and only 13 species were known from this biogeographically interesting island. In light of new field research, we provide an updated checklist to the Cypriot antlions, including seven species reported for the first time from the island. Of these, the findings of the Middle Eastern species Distoleon laticollis and Cueta kasyi are particularly noteworthy. The Cypriot antlion fauna appears dominated by widespread Mediterranean elements, with relatively few Middle Eastern and endemic species