School of Mathematical and Geospatial Sciences

Clenshaw's recurrence formula (with an associated sum) is an efficient way to evaluate a sum of coefficients multiplied by functions that obey a recurrence formula.  It has been used extensively in physical geodesy in the evaluation of sums of high degree and order spherical harmonic series approximating the earth's gravitational potential.  But less well known, and the subject of this paper, are applications in map projections where Clenshaw's method is used to develop compact formula for meridian distance and for computation of coordinates, grid convergence and point scale factor on the Transverse Mercator (TM) projection using the Karney-Krueger equations.

The Universal Transverse Mercator (UTM) coordinate system has at its core, equations that enable the transformations from geographic to grid coordinates and vice versa.  These equations have a long history stretching back to Gauss and his survey of Hannover in the early 1800's but their modern formulation is due to L. Krueger (1912) who synthesised Gauss’ and other work on the transverse Mercator (TM) projection of the ellipsoid.  Krueger developed two methods of transformation and the equations of his second method have become the de facto standard for the UTM and other TM projection systems.  Unfortunately these are complicated and have limited accuracy.  But the equations for Krueger’s first method which do not suffer from these accuracy limitations are undergoing a renaissance and a recent study by Charles Karney (2011) has given these equations a ‘make over’.  This paper gives some insight into the development and use of the Karney-Krueger equations.

One of the key responsibilities of any government is to communicate and disseminate safety information and warnings to the general public in case of an emergency. Traditionally, warnings are issued by the government through a broadcast approach using communication channels such as TV and radio. However this monopolistic approach is now challenged by new technologies and media capable of providing individualised warnings to personal mobile devices. Location-based emergency services and mobile alerts are becoming increasingly prevalent in the provision of emergency warnings. These new modes of emergency services have been adopted by several countries worldwide including Australia. One example is the Australian National Emergency Alert (EA) which is a telephone-based service enhanced with location-based capabilities. This paper introduces the concept of applying global satellite navigation systems such as the Japanese satellite system in the domain of emergency warning and alerting. The Japanese satellite warning system can be tailored to transmit real-time location-based emergency warnings to people's mobile devices while not being constrained by the limitations of ground-based communication technologies. A key advantage of satellite based communication is its high resilience to communication network overload and failure of ground systems and network infrastructure during a disaster. This enables people to obtain necessary information anywhere (outdoor) and anytime during times of disaster. A satellite-based warning system could also be integrated with existing warning services and be used as a complementary technology. This paper examines opportunities and challenges for using satellite navigation systems to deliver warnings and safety messages during emergencies and disasters.

Atmospheric water vapour (AWV) plays an important role in the pursuit of weather research, in particular extreme weather phenomena. Conventional atmospheric sounding methods including radiosonde and water vapour radiometer (WVR)) have the disadvantages of low spatial or temporal resolutions or high cost. As an emerging remote sensing approach of AWV, GPS is an ideal complement due to its unique advantages of 24-hour availability, high accuracy and low cost. As a critical part of the Australian positioning infrastructure, several regional Continuously Operating Reference Stations (CORS) networks have been established in the past two decades. The huge amount of GPS measurements provided by these CORS infrastructures are a rich data source that can be used for many applications in addition to positioning. This research aims to use GPS observations from Australian CORS networks to derive values of local atmospheric variables for weather prediction and severe weather monitoring. Our initial research task was to investigate approaches to obtain the GPS-derived tropospheric zenith total delay (ZTD) which is directly related to AWV. Preliminary results from both Precise Point Positioning (PPP) and Double Difference (DD) approaches available in Bernese software are presented in this paper. GPS data for the periods of the three heavy storm events occurred in Victoria (2012), Queensland (2011) and Victoria (2010) were selected for testing. The results showed that the GPS-derived ZTD from both PPP and DD agreed with the ZTD derived or provided from other data sources, including IGS tropospheric products from Center for Orbit Determination in Europe (CODE), and synoptic and radiosonde data from the Australian Bureau of Meteorology, at the level of several millimetres. This implies that the use of GPS observations from the well-distributed national CORS infrastructure over Australia to complement the current atmospheric sounding systems is promising. It has great potential to use these GPS observations to obtain atmospheric variable values with high spatial-temporal resolution, thanks to the all-day GPS observability and the dense distribution of the CORS networks. The synthetic integration of the GPS-derived atmospheric results with meteorological data from other space-and ground-based atmospheric sensors has significance for severe weather monitoring and prediction for the Australian region.

Lei de Introdução às Normas do Direito Brasileiro-disposições sobre segurança jurídica e eficiência na criação e na aplicação do direito público. Deste modo, muitas dúvidas têm surgido acerca da convivência entre a regra geral de direito tributário, inserta no Art. 144 do Código Tributário Nacional, de que a lei vigente à época dos fatos geradores deve ser levada em conta ao deslinde de uma questão e que a jurisprudência majoritária à época dos mesmos fatosse modificadanão deve servir de parâmetro para a tomada das decisões.

We present a comparison of atmospheric precipitable water vapor (PWV) derived from ground-based global positioning system (GPS) receiver with traditional radiosonde measurement and very long baseline interferometry (VLBI) technique for a five-year period (2008–2012) using Australian GPS stations. These stations were selectively chosen to provide a representative regional distribution of sites while ensuring conventional meteorological observations were available. Good agreement of PWV estimates was found between GPS and VLBI comparison with a mean difference of less than 1 mm and standard deviation of 3.5 mm and a mean difference and standard deviation of 0.1 mm and 4.0 mm, respectively, between GPS and radiosonde measurements. Systematic errors have also been discovered during the course of this study, which highlights the benefit of using GPS as a supplementary atmospheric PWV sensor and calibration system. The selected eight GPS sites sample different climates across Australia co...

Results of analysis of meteorological variables (temperature and moisture) in the Australasian region using the global positioning system (GPS) radio occultation (RO) and GPS ground-based observations verified with in situ radiosonde (RS) data are presented. The potential of using ground-based GPS observations for retrieving column integrated precipitable water vapour (PWV) over the Australian continent has been demonstrated using the Australian ground-based GPS reference stations network. Using data from the 15 ground-based GPS stations, the state of the atmosphere over Victoria during a significant weather event, the March 2010 Melbourne storm, has been investigated, and it has been shown that the GPS observations has potential for monitoring the movement of a weather front that has sharp moisture contrast. Temperature and moisture variability in the atmosphere over various climatic regions (the Indian and the Pacific Oceans, the Antarctic and Australia) has been examined using satellite-based GPS RO and in situ RS observations. Investigating recent atmospheric temperature trends over Antarctica, the time series of the collocated GPS RO and RS data were examined, and strong cooling in the lower stratosphere and warming through the troposphere over Antarctica has been identified, in agreement with outputs of climate models. With further expansion of the Global Navigation Satellite Systems (GNSS) system, it is expected that GNSS satellite-and ground-based measurements would be able to provide an order of magnitude larger amount of data which in turn could significantly advance weather forecasting services, climate monitoring and analysis in the Australasian region.