How to process radio occultation data: 1. From time series of frequency residuals to vertical profiles of atmospheric and ionospheric properties

Expertise in processing radio occultation observations, which provide vertical profiles of atmospheric and ionospheric properties from measurements of the frequency of radio signals, is not widespread amongst the planetary science community. In order to increase the population of radio occultation processing experts, which will have positive consequences for this field, here we provide detailed instructions for one critical aspect of radio occultation data processing: how to obtain a series of bending angles as a function of the ray impact parameter from a time series of frequency residuals. As developed, this tool is valid only for one-way, single frequency occultations at spherically symmetric objects, and is thus not immediately applicable to either two-way occultations, such as those of Mars Express, or occultations at oblate objects, such as Jupiter or Saturn. This tool is demonstrated successfully on frequency residuals from a Mars Global Surveyor occultation at Mars, and the resultant set of bending angles and impact parameters are used to obtain vertical profiles of ionospheric electron density, neutral atmospheric number density, mass density, pressure, and temperature via the usual Abel transform. The root-mean-square difference between electron densities in the ionospheric profile derived herein and archived electron densities is 7×10[superscript 8] m[superscript −3]. At the lowest altitudes, temperatures in the neutral atmospheric profile derived herein differ from archived neutral temperatures by less than 0.1 K. Software programs that implement these procedures accompany this paper and may be used to extract scientifically useful data products from lower-level data sets

The invasive Parthenium hysterophorus L. has limited impact on soil chemistry and enzyme activities but influences above and below ground bio-diversity

The invasive Parthenium hysterophorus L., a Weed of National Significance, is pervasive in agriculture, conservation and disturbed lands of central Queensland. In recent years, it has spread to the eastern and southern parts of the State and has the potential for incursion to the neighbouring States of New South Wales and Northern Territory, especially in view of climate change. However, very little work (most done overseas with inconsistent findings) has been reported on the weed’s impact on soil processes and native biodiversity. The work reported herein (involving soil sampling across multiple sites in central Queensland in parthenium weed infested and non-infested habitats) showed that due to the weed’s annual growth habit, a null effect was detected for soil chemistry (both micro- and macro-nutrients) and enzyme activities (β-glucosidase, fluorescein diacetate (FDA) hydrolysis and total microbial nitrogen and carbon). In contrast, significant negative impacts of parthenium weed infestation were observed for both below-ground (soil seed bank) and above-ground composition and diversity of co-occurring plant species. The results are discussed in terms of sampling methodology, adaptive pasture management, the weed’s growth habit and its ‘perceived’ position on Queensland weed list for risk assessment (based on impact, abundance and spread) and management

An inventory of Queensland prioritised invasive plant species for management and research

There are currently ~300 declared weeds in Queensland (QLD), Australia, but this list requires a review as the last known exercise dealing with weed risk assessment and prioritisation was undertaken about two decades ago. In this paper we propose an updated list of invasive alien (plant) species of significant concern in QLD, based on information derived from pest management plans of local governments, herbarium records and published/ grey literature, expert knowledge, and opinion from diverse groups of stakeholders. Weed diversity varies significantly between local government areas and regions. Regions on the mainland eastern seaboard of the State share similar weed communities, unlike western regions and the Torres Strait islands, which share fewer, weed species. Stakeholders identified the top research and management priorities for the weed list. These were: studies involving biological control options (34.8% of respondents), public awareness and education (18.5%), effective herbicide-use and application techniques (15.2%), ecology, taxonomy and risk analysis (11.5%), and adaptive pasture management (9.3%). Based on occurrence and distribution across local government areas/regional jurisdictions and onground stakeholders’ perceived weed severity, a weed priority list of high-medium and-low impact scores for policy, research and management was compiled for each region and State-wide