Over the last decade there has been an exponential growth in MT data acquisition over the Australian Continent through collaboration between Geoscience Australia, state and territory governments and academics. This data is resulting in a step change in our understanding of the lithosphere and basin architecture. Abstract submitted/presented at 2017 Target Conference (https://www.aig.org.au/events/target-2017/)

There are a number of global initiatives to understand and mitigate the impacts of extreme space weather on critical infrastructure and modern society. This paper provides the results of an analysis to estimate extreme geoelectric field values for the Australian region to facilitate evaluation of Australia's power system response to extreme geomagnetic storms. Geoelectric fields are calculated using a grid of modeled magnetotelluric impedance tensors obtained from a 3‐D conductivity model of the Australian region. Statistical metrics derived from grids of geoelectric field time series are analyzed as a function of Dst index for different storm days to extrapolate geoelectric fields to extreme storm levels over a range of ground conductivity conditions. For Carrington event storm levels, geoelectric field values of 5.3 ± 3.8 V/km in the north‐south direction and 9.6 ± 4.3 V/km in the east-west direction are expected for areas of electrically resistive rocks near coastlines that are adjacent to deep highly conductive oceans, and inland, where there are large contrasts between the electrical conductivities of different rock types across Australia. Further, geoelectric field values may change by at least an order of magnitude over the grid spacing interval of 50 km in these areas. The results of the analysis also suggest that upscaling grids of geoelectric field time series derived from an observed storm by the ratio of extreme storm Dst to the observed storm Dst are a valid approach for the Australian region that provides extreme storm scenarios for different storm morphologies. <b>Citation:</b> Marshall, R., Dziura, L., Wang, L., Young, J., & Terkildsen, M. (2020). Estimating extreme geoelectric field values for the Australian region. <i>Space Weather</i>, 18, e2020SW002512. https://doi.org/10.1029/2020SW002512

Space weather manifests in power networks as quasi‐DC currents flowing in and out of the power system through the grounded neutrals of high‐voltage transformers, referred to as geomagnetically induced currents. This paper presents a comparison of modeled geomagnetically induced currents, determined using geoelectric fields derived from four different impedance models employing different conductivity structures, with geomagnetically induced current measurements from within the power system of the eastern states of Australia. The four different impedance models are a uniform conductivity model (UC), one‐dimensional n‐layered conductivity models (NU and NW), and a three‐dimensional conductivity model of the Australian region (3DM) from which magnetotelluric impedance tensors are calculated. The modeled 3DM tensors show good agreement with measured magnetotelluric tensors obtained from recently released data from the Australian Lithospheric Architecture Magnetotelluric Project. The four different impedance models are applied to a network model for four geomagnetic storms of solar cycle 24 and compared with observations from up to eight different locations within the network. The models are assessed using several statistical performance parameters. For correlation values greater than 0.8 and amplitude scale factors less than 2, the 3DM model performs better than the simpler conductivity models. When considering the model performance parameter, P, the highest individual P value was for the 3DM model. The implications of the results are discussed in terms of the underlying geological structures and the power network electrical parameters. <b>Citation:</b> Marshall, R. A., Wang, L., Paskos, G. A., Olivares‐Pulido, G., Van Der Walt, T., Ong, C., et al. (2019). Modeling geomagnetically induced currents in Australian power networks using different conductivity models. <i>Space Weather</i>, 17. https://doi.org/10.1029/2018SW002047

Geoscience Australia is developing technology, infrastructure and the tools needed through its Positioning Australia program to provide accurate, reliable and real-time positioning information across Australia and its maritime zones. This capability is being achieved through technology and infrastructure initiatives described in the flyer. This flyer was created for the International Mining and Resources Conference (IMARC) taking place on 31 Jan to 3 Feb 2022.

This Record details rhenium–osmium (Re–Os) dating of molybdenite separated from quartz veins associated with tungsten mineralisation at the Hit or Miss deposit of the Hatches Creek tungsten field, Warramunga Province. Two samples of molybdenite were collected from the former mine: sample FR17MVM001 as drill chips from a tungsten-mineralised quartz vein in drillhole HCRC021, and sample FR17MVM002 from a quartz vein in surface workings associated with tungsten and molybdenum. Molybdenite was dated to determine an absolute age for tungsten mineralisation at the deposit. The Re–Os molybdenite model ages obtained were 1677 ± 10 Ma and 1602 ± 9 Ma respectively. These ages are tentatively interpreted as mineralisation and/or remobilisation ages for molybdenum and tungsten, and the associated bismuth and copper at the Hit or Miss deposit; they also provide timing constraints on mineralisation in the wider Hatches Creek tungsten field. Low Re concentrations in the samples (1–2 ppm) are consistent with an evolved crustal source for the tungsten mineralisation. The older of the two Re–Os model ages is broadly consistent with previous age determinations for tungsten mineralisation and felsic intrusions in the Warramunga Province using Ar–Ar muscovite and U–Pb zircon dating methods. Although the geological significance of the new Re–Os molybdenite age is uncertain, the results are tentatively interpreted to record a protracted episode of tungsten, copper and molybdenum mineralisation in the Warramunga Province between ca 1700 –1600 Ma, associated with evolved felsic intrusions. <b>BIBLIOGRAPHIC REFERENCE: </b>McGloin MV, , Huston DH and Norman M, 2019. Summary of results. Re–Os molybdenite dating of the Hit or Miss deposit, Hatches Creek tungsten field, Warramunga Province. <i>Northern Territory Geological Survey</i>, Record 2019-010.

In the last decade, satellite derived standard land products have increasingly been produced for medium resolution satellites such as Landsat and (more recently) Sentinel-2. These mostly involve estimating surface reflectance and surface temperature. The products generally remove or standardise atmospheric effects with some also normalizing for surface bidirectional reflectance distribution function (BRDF) and terrain illumination effects to provide consistent time series and mosaics. The products have been used in various land surface applications, e.g., land cover, fractional cover and water identification, including flooding, crop monitoring and other time series analysis. However, the products are generally not immediately sufficient for applications over persistent water areas, such as estimating water quality, benthic cover, sediment transport, erosion and shallow water bathymetry. These need additional corrections with different physics that are not included in standard land products. In this paper, a method is proposed that treats persistent water areas separately within the standard product and includes corrections not generally applied to the land. The processing has been designed to be fully consistent between water and land in atmospheric correction and definition of reflectance factors so that they can be combined in the same time series and form mosaics. The first step in this process was acquisition of an effective and up to date classification to separate the persistent water and land. The water areas are then atmospherically corrected in the same way as the land but not treated for BRDF or shading effects as are the land areas. For the water areas, adjacency effects are more significant near water-land interfaces and water surface effects have different physics from land surfaces. The extra corrections currently include correction for adjacency effects as well as regional sun glint and sky radiation effects. The water mask and these corrections have been added to the current existing atmospheric, BRDF and terrain corrected surface reflectance product (standard product) from Geoscience Australia (GA). However, at the scale of the Landsat and higher resolution satellite images, residual local surface and bidirectional effects still occur and are discussed in this paper. In this paper, results from the new processing strategy have been compared with GA standard products in test images of Canberra and the North Queensland coast near Ingham and used as a basis to discuss the likely residuals of surface and atmospheric effects and options for the inclusion of methods to overcome them in a standard product. The results show that: • Both inland and sea water signatures behave as expected from other data and models. • Adjacency correction seems most useful where a water-Land interface is close to the water body. • Sky glint removal is sometimes too great in Canberra site when water is shielded by local terrain. • Sun and sky glint correction greatly improves the coast and deep sea water signatures. This Abstract was presented at the 22nd International Congress on Modelling and Simulation (MODSIM2017) Hobart Tasmania (https://www.mssanz.org.au/modsim2017/)

Many atmospheric correction schemes of radiance-based optical satellite data require the selection of normalized solar spectral irradiance models at the top of atmosphere (TOA). However, there is no scientific consensus in literature as to which available model is most suitable. This article examines five commonly used models applied to Landsat 8 Operational Land Imager (OLI) TOA radiance and reflectance products to assess the accuracy and stability between models used to derive surface reflectance products. It is assumed that the calibration of the United States Geological Survey (USGS) Landsat 8 OLI TOA reflectance and radiance products are accurate to currently claimed levels. The results show that the retrieved surface reflectance can exhibit significant variations when different solar irradiance models are used, especially in the OLI coastal blue band at 443 nm. From the five solar irradiance models, the Kurucz 2005 model showed the least bias compared with OLI TOA reflectance product and least variance in surface reflectance. Furthermore, improvement was obtained by adjusting the total solar irradiance (TSI) normalization, and additional validation was provided using observed in situ water leaving reflectance data. The results from this article are particularly relevant to aquatic applications and to satellite sensors that provide TOA radiance such as previous Landsat and other current and historical missions. <b>Citation:</b> F. Li, D. L. B. Jupp, S. Sagar and T. Schroeder, "The Impact of Choice of Solar Spectral Irradiance Model on Atmospheric Correction of Landsat 8 OLI Satellite Data," in IEEE Transactions on Geoscience and Remote Sensing, vol. 59, no. 5, pp. 4094-4104, May 2021, doi: 10.1109/TGRS.2020.3011006.

An atmospheric correction algorithm for medium-resolution satellite data over general water surfaces (open/coastal, estuarine and inland waters) has been assessed in Australian coastal waters. In situ measurements at four match-up sites were used with 21 Landsat 8 images acquired between 2014 and 2017. Three aerosol sources (AERONET, MODIS ocean aerosol and climatology) were used to test the impact of the selection of aerosol optical depth (AOD) and Ångström coefficient on the retrieved accuracy. The initial results showed that the satellite-derived water-leaving reflectance can have good agreement with the in situ measurements, provided that the sun glint is handled effectively. Although the AERONET aerosol data performed best, the contemporary satellite-derived aerosol information from MODIS or an aerosol climatology could also be as effective, and should be assessed with further in situ measurements. Two sun glint correction strategies were assessed for their ability to remove the glint bias. The most successful one used the average of two shortwave infrared (SWIR) bands to represent sun glint and subtracted it from each band. Using this sun glint correction method, the mean all-band error of the retrieved water-leaving reflectance at the Lucinda Jetty Coastal Observatory (LJCO) in north east Australia was close to 4% and unbiased over 14 acquisitions. A persistent bias in the other strategy was likely due to the sky radiance being non-uniform for the selected images. In regard to future options for an operational sun glint correction, the simple method may be sufficient for clear skies until a physically based method has been established. <b>Citation:</b> Li, F.; Jupp, D.L.B.; Schroeder, T.; Sagar, S.; Sixsmith, J.; Dorji, P. Assessing an Atmospheric Correction Algorithm for Time Series of Satellite-BasedWater-Leaving Reflectance Using Match-Up Sites in Australian CoastalWaters. Remote Sens. 2021, 13, 1927. https://doi.org/10.3390/rs13101927