Operational Wave, Current, and Wind Measurements With the Pisces HF Radar

This paper presents results of a trial of a Pisces HF radar system aimed at assessing its use as a component of a wave-monitoring network being installed around the coasts of England and Wales. The radar system has been operating since December 2003 and the trial continued to June 2005. The data have been processed in near-real time and displayed on a website. Radar measurements of the directional spectrum and derived parameters are compared with those measured with a directional waverider and with products from the Met Office, United Kingdom, operational wave model. Radar measurements of currents and winds are also compared with Met Office model products and, in the case of winds, with the QuikSCAT scatterometer. Statistics on data availability and accuracy are presented. The results demonstrate that useful availability and accuracy in wave and wind parameters are obtained above a waveheight threshold of 2 m and at ranges up to 120 km at the radar operating frequencies (7-10 MHz) used. Waveheight measurements above about 1 m can be made with reasonable accuracy (e.g., mean difference of 2.5% during January-February 2004). Period and direction parameters in low seas are often contaminated by noise in the radar signal. The comparisons provide some evidence of wave model limitations in offshore wind and swell conditions     

VLBI observations of GNSS-satellites: from scheduling to analysis

The possibility of observing satellites with the very long baseline interferometry (VLBI) technique has been discussed for several years in the geodetic community, with observations of either existing satellites of the global navigation satellite systems or of satellites dedicated to realise a space tie. Such observations were carried out using the Australian telescopes in Hobart and Ceduna which, for the first time, integrated all the necessary steps: planning the observations (automated scheduling), correlation of the data and the generation of a series of time delay observables suitable for a subsequent geodetic analysis. We report on the development of new and the adaptation of existing routines for observing and data processing, focusing on technology development. The aim was to use methods that are routinely used in geodetic VLBI. A series of test experiments of up to six hours duration was performed, allowing to improve the observations from session to session and revealing new problems still to be solved. The newly developed procedures and programs now enable more observations. Further development assumed, this bears the prospect of being directly applied to the observation of dedicated space-tie satellites.     

Solar Scintillometry: Calibration of Signals and its Use for Seeing Measurements

Since 1993 it is known that there is a good correlation between the scintillation in the solar irradiance and solar image quality (Seykora, 1993). This effect is now being used in a number of experiments to evaluate solar image quality and to measure site seeing. In this paper we explore further the calibration of this scintillation (_I) in terms of the Fried parameter (_r0) taking into account variations in the refractive index structure constant C _N ² with height (h), zenith distance () dependence and the effects of wind velocities. A variant in the scintillometer setup is proposed which decreases sharply the dependance on C _N ² , , and the wind velocities. It uses an array of scintillometers. The same array can be used to measure theC _N ² profile with height. Some preliminary results of the calibration of current NSO site survey measurements are presented.     

Book reviews

Third World politics: a concise introduction

J. Haynes, 1996

Blackwell, Oxford

15 × 23 cm, viii + 227pp., ISBN 0–631–19778–8, £14.99/US$19.95 (soft)

Thirdspace: journeys to Los Angeles and other real‐and‐imagined places

E.W. Soja, 1996

Blackwell, Cambridge, MA

17 × 25 cm, xii + 334pp., ISBN 1–55786–675–9, £14.99/US$20.95 (soft)

Alpine Tasmania: an illustrated guide to the flora and vegetation

J. Kirkpatrick, 1997

Oxford University Press, Melbourne

14 × 22 cm, xii+ 196 pp., ISBN 0–19–553753‐X, A$24.95

Spatial behavior: a geographic perspective

R.G. Golledge. & R.J. Stimson, 1997

The Guilford Press, New York

16 × 24 cm, xx + 620 pp., ISBN 1–57230–050–7, A$39.95 (soft)

Pacific Rim development: integration and globalisation in the Asia‐Pacific economy,(Studies in World Affairs XIII)

P.J. Rimmer (ed.), 1997

Allen & Unwin, Sydney

14 × 22 cm, xiii + 294 pp., ISBN 1–86373–978–5, A$24.95 (soft)     

Environmental evaluation of elemental cesium and strontium contents and their isotopic activity concentrations in different soils of La Mancha (Central Spain)

Cesium and Strontium concentrations were analyzed in eight pedogenetic soil profiles developed on different rocks from a semiarid mediterranean region: La Mancha (Central Spain). Concentration activities of ¹³⁷Cs and ⁹⁰Sr, as for some soil properties, were also measured. The results are presented in this document: Cs concentrations range between 0.4 and 18.3 mg kg⁻¹ and Sr varies widely between 11.0 and 3,384 mg kg⁻¹. Therefore, it is clear that there is a broad range of concentrations and there are also values significantly higher than the average values stated by several authors. Concentrations of long-life artificial radionuclides (¹³⁷Cs, ⁹⁰Sr) were determined in some of the same soils. The activity concentration mean values (Bq kg⁻¹) were ranging between 0.82 and 21.76 for ¹³⁷Cs and ⁹⁰Sr variations range between 6.73 and 0.35. There were no significant correlations between radionuclides and stable trace elements. The data indicate that the soils do not show significant radioactivity of these elements and therefore they do not pose a danger. By the same token, no risk of contamination by this activity was detected. Finally, spatial patterns seem to be affected by the soil type and some soil properties.     

Digital thermal monitoring of the Amazon forest: an intercomparison of satellite and reanalysis products

Remote sensing and climate digital products have become increasingly available in recent years. Access to these products has favored a variety of Digital Earth studies, such as the analysis of the impact of global warming over different biomes. The study of the Amazon forest response to drought has recently received particular attention from the scientific community due to the occurrence of extreme droughts and anomalous warming over the last decade. This paper focuses on the differences observed between surface thermal anomalies obtained from remote sensing moderate resolution imaging spectroradiometer (MODIS) and climatic (ERA-Interim) monthly products over the Amazon forest. With a few exceptions, results show that the spatial pattern of standardized anomalies is similar for both products. In terms of absolute anomalies, the differences between the two products show a bias near to zero with a standard deviation of around 0.2?K, although the differences can be up to 1?K over particular regions and months. Despite this general agreement, the proper filtering of MODIS daily values in order to construct a new monthly product showed a dramatic reduction in the number of reliable pixels during the rainy season, while for the dry season this reduction is only seen in Northern Amazonia.