High resolution spatial variability in spring snowmelt for an Arctic shrub-tundra watershed

Arctic tundra environments are characterized by spatially heterogeneous end-of-winter snow cover because of high winds that erode, transport and deposit snow over the winter. This spatially variable end-of-winter snow cover subsequently influences the spatial and temporal variability of snowmelt and results in a patchy snowcover over the melt period. Documenting changes in both snow cover area (SCA) and snow water equivalent (SWE) during the spring melt is essential for understanding hydrological systems, but the lack of high-resolution SCA and SWE datasets that accurately capture micro-scale changes are not commonly available, and do not exist for the Canadian Arctic. This study applies high-resolution remote sensing measurements of SCA and SWE using a fixed-wing Unmanned Aerial System (UAS) to document snowcover changes over the snowmelt period for an Arctic tundra headwater catchment. Repeat measurements of SWE and SCA were obtained for four dominant land cover types (tundra, short shrub, tall shrub, and topographic drift) to provide observations of spatially distributed snowmelt patterns and basin-wide declines in SWE. High-resolution analysis of snowcover conditions over the melt reveal a strong relationship between land cover type, snow distribution, and snow ablation rates whereby shallow snowpacks found in tundra and short shrub regions feature rapid declines in SWE and SCA and became snow-free approximately 10 days earlier than deeper snowpacks. In contrast, tall shrub patches and topographic drift regions were characterized by large initial SWE values and featured a slow decline in SCA. Analysis of basin-wide declines in SCA and SWE reveal three distinct melt phases characterized by 1) low melt rates across a large area resulting in a minor change in SCA, but a very large decline in SWE with, 2) high melt rates resulting in drastic declines in both SCA and SWE, and 3) low melt rates over a small portion of the basin, resulting in little change to either SCA or SWE. The ability to capture high-resolution spatio-temporal changes to tundra snow cover furthers our understanding of the relative importance of various land cover types on the snowmelt timing and amount of runoff available to the hydrological system during the spring freshet

When 'us vs. them' goes one step further : double alienation in An Garda Siochána

In policing literature, the ‘us versus them’ paradigm is well documented, whereby ‘us’ is the police and ‘them’ is the public. But what happens when frontline officers are separated both from society and from those within their own organisation? This research looks down a new pathway of what it means to be doubly alienated in an atmosphere that already makes sociability difficult. In Ireland, there has been little research to date on An Garda Síochána, Ireland’s national police force, and nothing that has addressedthe cross roads these officers find themselves in under these circumstances. The organisation espouses a culture of conform or face the consequences. In these particular circumstances, officers must then either compromise their integrity or become pariahs in the organisation. This qualitative exploration analyses documents to understand under what conditions officers must make these decisions and how they are received by the public and the organisation when they do

Improvements in prevalence trend fitting and incidence estimation in EPP 2013

OBJECTIVE: Describe modifications to the latest version of the Joint United Nations Programme on AIDS (UNAIDS) Estimation and Projection Package component of Spectrum (EPP 2013) to improve prevalence fitting and incidence trend estimation in national epidemics and global estimates of HIV burden. METHODS: Key changes made under the guidance of the UNAIDS Reference Group on Estimates, Modelling and Projections include: availability of a range of incidence calculation models and guidance for selecting a model; a shift to reporting the Bayesian median instead of the maximum likelihood estimate; procedures for comparison and validation against reported HIV and AIDS data; incorporation of national surveys as an integral part of the fitting and calibration procedure, allowing survey trends to inform the fit; improved antenatal clinic calibration procedures in countries without surveys; adjustment of national antiretroviral therapy reports used in the fitting to include only those aged 15–49 years; better estimates of mortality among people who inject drugs; and enhancements to speed fitting. RESULTS: The revised models in EPP 2013 allow closer fits to observed prevalence trend data and reflect improving understanding of HIV epidemics and associated data. CONCLUSION: Spectrum and EPP continue to adapt to make better use of the existing data sources, incorporate new sources of information in their fitting and validation procedures, and correct for quantifiable biases in inputs as they are identified and understood. These adaptations provide countries with better calibrated estimates of incidence and prevalence, which increase epidemic understanding and provide a solid base for program and policy planning

Engaged learning in Europe

Globally, there are growing calls for Higher Education Institutions to become more civically engaged and socially relevant while increasing public interest in the impact of universities on their localities and regions. Engaged Learning facilitates students to apply theory to real-world contexts outside of the University and to co-produce knowledge with and for the community. Engaged Learning provides students with the skills which increase their employability, and improve their personal and professional development, while communities gain access to skills to help develop, evaluate, or communicate their work with regard to actual societal challenges. To enhance the knowledge and understanding of what constitutes a successful and sustainable Engaged Learning programme an in-depth view is provided into practices from six institutional contexts from six countries throughout Europe. Highlighted is the diversity and flexibility to be found within Engaged Learning initiatives. However, the one constant is each initiative’s commitment to a concept where reciprocity between the students, universities, and communities, is prioritised. While the examples themselves differ in their structure and intended outcomes, this diversity is a benefit of Engaged Learning and further cements the varied nature across the disciplines and Europe

Impact of the January 2012 solar proton event on polar mesospheric clouds

We use data from the Aeronomy of Ice in the Mesosphere mission and simulations using the Whole Atmosphere Community Climate Model to determine the impact of the 23–30 January 2012 solar proton event (SPE) on polar mesospheric clouds (PMCs) and mesospheric water vapor. We see a small heating and loss of ice mass on 26 January that is consistent with prior results but is not statistically significant. We also find a previously unreported but statistically significant ~10% increase in ice mass and in water vapor in the sublimation area in the model that occurs in the 7 to 14 days following the start of the event. The magnitude of the response to the January 2012 SPE is small compared to other sources of variability like gravity waves and planetary waves; however, sensitivity tests suggest that with larger SPEs this delayed increase in ice mass will increase, while there is little change in the loss of ice mass early in the event. The PMC response to SPEs in models is dependent on the gravity wave parameterization, and temperature anomalies from SPEs may be useful in evaluating and tuning gravity wave parameterizations

Relative Importance of Nitric Oxide Physical Drivers in the Lower Thermosphere

Nitric oxide (NO) observations from the Solar Occultation for Ice Experiment and Student Nitric Oxide Explorer satellite instruments are investigated to determine the relative importance of drivers of short‐term NO variability. We study the variations of deseasonalized NO anomalies by removing a climatology, which explains between approximately 70% and 90% of the total NO budget, and relate them to variability in geomagnetic activity and solar radiation. Throughout the lower thermosphere geomagnetic activity is the dominant process at high latitudes, while in the equatorial region solar radiation is the primary source of short‐term NO changes. Consistent results are obtained on estimated geomagnetic and radiation contributions of NO variations in the two data sets, which are nearly a decade apart in time. The analysis presented here can be applied to model simulations of NO to investigate the accuracy of the parametrized physical drivers

Middle atmospheric ozone, nitrogen dioxide and nitrogen trioxide in 2002-2011: SD-WACCM simulations compared to GOMOS observations

Most of our understanding of the atmosphere is based on observations and their comparison with model simulations. In middle atmosphere studies it is common practice to use an approach, where the model dynamics are at least partly based on temperature and wind fields from an external meteorological model. In this work we test how closely satellite measurements of a few central trace gases agree with this kind of model simulation. We use collocated vertical profiles where each satellite measurement is compared to the closest model data. We compare profiles and distributions of O3, NO2 and NO3 from the Global Ozone Monitoring by Occultation of Stars instrument (GOMOS) on the Envisat satellite with simulations by the Whole Atmosphere Community Climate Model (WACCM). GOMOS measurements are from nighttime. Our comparisons show that in the stratosphere outside the polar regions differences in ozone between WACCM and GOMOS are small, between 0 and 6%. The correlation of 5-day time series show a very high 0.9-0.95. In the tropical region 10° S-10° N below 10hPa WACCM values are up to 20% larger than GOMOS. In the Arctic below 6 hPa WACCM ozone values are up to 20% larger than GOMOS. In the mesosphere between 0.04 and 1hPa the WACCM is at most 20% smaller than GOMOS. Above the ozone minimum at 0.01hPa (or 80km) large differences are found between WACCM and GOMOS. The correlation can still be high, but at the second ozone peak the correlation falls strongly and the ozone abundance from WACCM is about 60% smaller than that from GOMOS. The total ozone columns (above 50hPa) of GOMOS and WACCM agree within ±2% except in the Arctic where WACCM is 10% larger than GOMOS. Outside the polar areas and in the validity region of GOMOS NO2 measurements (0.3-37 hPa) WACCM and GOMOS NO2 agree within -5 to +25% and the correlation is high (0.7-0.95) except in the upper stratosphere at the southern latitudes. In the polar areas, where solar particle precipitation and downward transport from the thermosphere enhance NO2 abundance, large differences up to -90% are found between WACCM and GOMOS NO2 and the correlation varies between 0.3 and 0.9. For NO3, we find that the WACCM and GOMOS difference is between -20 and 5% with a very high correlation of 0.7-0.95. We show that NO3 values strongly depend on temperature and the dependency can be fitted by the exponential function of temperature. The ratio of NO3 to O3 from WACCM and GOMOS closely follow the prediction from the equilibrium chemical theory. Abrupt temperature increases from sudden stratospheric warmings (SSWs) are reflected as sudden enhancements of WACCM and GOMOS NO3 values

The 27-day solar rotational cycle response in the mesospheric metal layers at low latitudes

To investigate the response of the meteoric metal layers in the mesosphere and lower thermosphere region to the 27-day solar rotational cycle, a long-term simulation of the Whole Atmosphere Climate Community Model (WACCM) with the chemistry of three metals (Na, K, and Fe) was analysed. The correlation between variability in the metal layers and solar 27-day forcing during different phases of the solar 11-year cycle reveals that the response in the metal layers is much stronger during solar maximum. The altitude dependent correlation and sensitivity of the metal layers to the solar spectral irradiance demonstrates that there is a significant increase in sensitivity to solar rotational cycle with increasing altitude. Above 100 km, the sensitivity of the metals to changes of 10% in the SSI at Lyman-alpha is estimated to be -5%. A similar response is seen in Na layer measurements made by the OSIRIS instrument on the Odin satellite