What features make Pocket Beaches unique in Terms of Coastal Processes?

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Airborne bacterial populations above desert soils of the McMurdo Dry Valleys, Antarctica

Bacteria are assumed to disperse widely via aerosolized transport due to their small size and resilience. The question of microbial endemicity in isolated populations is directly related to the level of airborne exogenous inputs, yet this has proven hard to identify. The ice-free terrestrial ecosystem of Antarctica, a geographically and climatically isolated continent, was used to interrogate microbial bio-aerosols in relation to the surrounding ecology and climate. High-throughput sequencing of bacterial ribosomal RNA (rRNA) genes was combined with analyses of climate patterns during an austral summer. In general terms, the aerosols were dominated by Firmicutes, whereas surrounding soils supported Actinobacteria-dominated communities. The most abundant taxa were also common to aerosols from other continents, suggesting that a distinct bio-aerosol community is widely dispersed. No evidence for significant marine input to bio-aerosols was found at this maritime valley site, instead local influence was largely from nearby volcanic sources. Back trajectory analysis revealed transport of incoming regional air masses across the Antarctic Plateau, and this is envisaged as a strong selective force. It is postulated that local soil microbial dispersal occurs largely via stochastic mobilization of mineral soil particulates

Development of a Systems Model for Assessing Pathways to Resilient, Sustainable, and Profitable Agriculture in New Zealand

There is a clear research gap in understanding how future pathways and disruptions to the New Zealand (NZ) agricultural system will have an impact on the environment and productivity. Agriculture is in a period of significant change due to market disruptions, climate change, increasingly stringent environmental regulations, and emerging technologies. In NZ, agriculture is a key sector of the economy, therefore government and industry need to develop policies and strategies to respond to the risks and opportunities associated with these disruptors. To address this gap, there is a need to develop an assessment tool to explore pathways and interventions for increasing agricultural profitability, resilience, and sustainability over the next 5–30 years. A decision support tool was developed through Stella Architect, bringing together production, market values, land use, water use, energy, fertiliser consumption, and emissions from agricultural sectors (dairy, beef, sheep, cereals, horticulture, and forests). The parameters are customisable by the user for scenario building. Two future trend scenarios (Business as usual, Optimisation and technology) and two breakaway scenarios (Carbon farming, Reduction in dairy demand) were simulated and all met carbon emissions goals, but profitability differed. Future environmental regulations can be met by adjusting levers associated with technology, carbon offsets, and land use. The model supports the development and assessment of pathways to achieve NZ’s national agriculture goals and has the potential to be scaled globally

An Analysis of Agricultural Systems Modelling Approaches and Examples to Support Future Policy Development under Disruptive Changes in New Zealand

Agricultural systems have entered a period of significant disruption due to impacts from change drivers, increasingly stringent environmental regulations and the need to reduce unwanted discharges, and emerging technologies and biotechnologies. Governments and industries are developing strategies to respond to the risks and opportunities associated with these disruptors. Modelling is a useful tool for system conceptualisation, understanding, and scenario testing. Today, New Zealand and other nations need integrated modelling tools at the national scale to help industries and stakeholders plan for future disruptive changes. In this paper, following a scoping review process, we analyse modelling approaches and available agricultural systems’ model examples per thematic applications at the regional to national scale to define the best options for the national policy development. Each modelling approach has specificities, such as stakeholder engagement capacity, complex systems reproduction, predictive or prospective scenario testing, and users should consider coupling approaches for greater added value. The efficiency of spatial decision support tools working with a system dynamics approach can help holistically in stakeholders’ participation and understanding, and for improving land planning and policy. This model combination appears to be the most appropriate for the New Zealand national context

Simulation of the spatial distribution of mineral dust and its direct radiative forcing over Australia

Direct radiative forcing by mineral dust is important as it significantly affects the climate system by scattering and absorbing short-wave and long-wave radiation. The multi-angle imaging spectro radiometer (MISR) and cloud–aerosol lidar with orthogonal polarisation (CALIOP) aerosol data are used to observe mineral dust distribution over Australia. In addition, the weather research and forecasting with chemistry (WRF/Chem) model is used to estimate direct radiative forcing by dust. At the surface, the model domain clear-sky short-wave and long-wave direct radiative forcing by dust averaged for a 6-month period (austral spring and summer) was estimated to be −0.67 W m−2 and 0.13 W m−2, respectively. The long-wave warming effect of dust therefore offsets 19.4% of its short-wave cooling effect. However, over Lake Eyre Basin where coarse particles are more abundant, the long-wave warming effect of dust offsets 60.9% of the short-wave cooling effect. At the top of the atmosphere (TOA), clear-sky short-wave and long-wave direct radiative forcing was estimated to be −0.26 W m−2 and −0.01 W m−2, respectively. This leads to a net negative direct radiative forcing of dust at the TOA, indicating cooling of the atmosphere by an increase in outgoing radiation. Short-wave and long-wave direct radiative forcing by dust is shown to have a diurnal variation due to changes in solar zenith angle and in the intensity of infrared radiation. Atmospheric heating due to absorption of short-wave radiation was simulated, while the interaction of dust with long-wave radiation was associated with atmospheric cooling. The net effect was cooling of the atmosphere near the surface (below 0.2 km), with warming of the atmosphere at higher altitudes

Numerical modelling of thermally induced regional and local scale flows in MacKenzie Basin, New Zealand

Atmospheric flows that result from surface heating and cooling in complex, mountainous terrain encompass many scales. These flows are induced by horizontal thermal gradients in the atmosphere associated with topographic relief, and are most pronounced when synoptic pressure gradients are weak. At the small-scale end of the spectrum there are slope and along-valley winds, and at the larger scale there are plain-to-basin and plain-to-plateau flows. The intrusion of a recurring plain-to-basin wind system named the Canterbury Plains Breeze (CPB) into the MacKenzie Basin and Lake Tekapo region is described using both observational data and results from a numerical model. Observational data from a surface monitoring network designed to investigate local flows in the Lake Tekapo area show that the CPB has an important influence on the wind regime in this region. An atmospheric mesoscale numerical model was utilized to investigate the origin and forcing mechanisms for this flow. The mesoscale model was able to successfully simulate the CPB for a case study day using realistic synoptic scale winds. To isolate the major forcing mechanisms for this flow, additional idealized two- and three-dimensional numerical experiments were conducted. The idealized three-dimensional runs showed that the CPB is a not a sea breeze intrusion into the MacKenzie Basin as was previously thought, and could be generated by orography alone. The two-dimensional runs showed that although the sea breeze outside the basin does not have a direct impact on the CPB, it can influence the current's intensity by suppressing the mixed layer growth outside the basin, which increases the horizontal temperature gradient that forces the CPB. Other surface effects, such as soil moisture content and land use also seem to affect the characteristic features of the plain-to-basin flow. In addition, two high-resolution simulations were performed to investigate the interaction of the CPB with locally generated thermal flows around Lake Tekapo, where the surface monitoring network was established. Results show that early in the afternoon the CPB flows into the region as gap winds through the saddles in the Two Thumb Range, dominating the local winds. These gap winds are localized in nature, and the model runs suggest that the monitoring network was not dense enough to adequately describe the surface flow field around the lake. It is evident from this research that regional circulation systems, such as the CPB, could transport air pollutants significant distances from the coastal plains, over complex terrain into the relatively pristine environment of the South Island's mountain basins. A knowledge of the physical forcing mechanisms involved in such flows can therefore have important practical applications for air quality issues

Analysis of MODIS LST Compared with WRF Model and in situ Data over the Waimakariri River Basin, Canterbury, New Zealand

In this study we examine the relationship between remotely sensed, in situ and modelled land surface temperature (LST) over a heterogeneous land-cover (LC) enclosed in alpine terrain. This relationship can help to understand to what extent the remotely sensed data can be used to improve model simulations of land surface parameters such as LST in mountainous areas. LST from the MODerate resolution Imaging Spectro-radiometer (MODIS), the modelled surface skin temperature by the Weather Research and Forecasting (WRF) mesoscale numerical model and the in situ measurements of surface temperature are used in the analysis. The test-site is located in a mountain valley in the Southern Alps of New Zealand. Geospatial analysis in GIS is used to relate pixels, grid-cells and points from the MODIS LST, model simulations and the in situ data, respectively. Differences between LST from MODIS, the WRF model and the in situ data are presented with respect to surface LC at different times of day. Initial results from regression analysis of the three datasets showed a goodness of fit R2 coefficient of 0:77 for the model simulations and 0:35 for the MODIS LST. These values improved significantly when time-lags were considered and the few outliers were removed, giving R2 values of 0:80 for the model and 0:73 for the MODIS LST. These results show that the WRF model correlates better with the in situ measurements over various LC types in this region compared with the MODIS LST. Longer time-series, however, are required to draw more robust conclusions about the applicability of the MODIS LST product for improving WRF simulations over alpine complex terrain

Every breath you take? Environmental justice and air pollution in Christchurch, New Zealand

In a number of environmental-justice studies it has been noted that the exposure to an array of air pollutants varies between different social groups. This inequality in exposure is one possible explanation for the variations in pollution-related health outcomes such as lung cancer and other respiratory diseases. Previous environmental-justice studies that have focused upon air pollution have tended to be concerned with exposure to industrial and vehicle pollution and rely upon simple estimates of exposure, ignoring the complex interaction of emissions, topography, and meteorology that determine pollution levels in many urban areas. In this paper we use accurate and geographically detailed estimates of pollution calculated from an atmospheric dispersion model to examine issues of environmental justice related to air pollution sourced from domestic heating in Christchurch, New Zealand, a city with particularly high levels of particulate pollution during winter months. We consider whether there is a social gradient in exposure to air pollution in Christchurch by comparing estimates of particulate pollution for small areas across the city to a range of demographic and socioeconomic indicators including age, ethnicity, income, and deprivation. Furthermore, we examine whether there is a social gradient in exposure to extreme pollution episodes. We demonstrate that different social groups in the Christchurch population are exposed to different levels of both ambient air pollution and extreme air-pollution episodes. In particular, pollution is significantly higher among more disadvantaged communities. We also find evidence which suggests that the groups responsible for producing a large proportion of the pollution in Christchurch are not the same groups exposed to high levels of particulate air pollution.

Identifying hydro-meteorological events from precipitation extremes indices and other sources over northern Namibia, Cuvelai Basin

Worldwide, more than 40% of all natural hazards and about half of all deaths are the result of flood disasters. In northern Namibia flood disasters have increased dramatically over the past half-century, along with associated economic losses and fatalities. There is a growing concern to identify these extreme precipitation events that result in many hydro-meteorological disasters. This study presents an up to date and broad analysis of the trends of hydrometeorological events using extreme daily precipitation indices, daily precipitation data from the Grootfontein rainfall station (1917–present), regionally averaged climatologies from the gauged gridded Climate Research Unit (CRU) product, archived disasters by global disaster databases, published disaster events in literature as well as events listed by Mendelsohn, Jarvis and Robertson (2013) for the data-sparse Cuvelai river basin (CRB). The listed events that have many missing data gaps were used to reference and validate results obtained from other sources in this study. A suite of ten climate change extreme precipitation indices derived from daily precipitation data (Grootfontein rainfall station), were calculated and analysed. The results in this study highlighted years that had major hydro-meteorological events during periods where no data are available. Furthermore, the results underlined decrease in both the annual precipitation as well as the annual total wet days of precipitation, whilst it found increases in the longest annual dry spell indicating more extreme dry seasons. These findings can help to improve flood risk management policies by providing timely information on historic hydro-meteorological hazard events that are essential for early warning and forecasting