Solar modulation in surface atmospheric electricity

The solar wind modulates the flux of galactic cosmic rays impinging on Earth inversely with solar activity. Cosmic ray ionisation is the major source of air’s electrical conductivity over the oceans and well above the continents. Differential solar modulation of the cosmic ray energy spectrum modifies the cosmic ray ionisation at different latitudes,varying the total atmospheric columnar conductance. This redistributes current flow in the global atmospheric electrical circuit, including the local vertical current density and the related surface potential gradient. Surface vertical current density and potential gradient measurements made independently at Lerwick Observatory,Shetland,from 1978 to 1985 are compared with modelled changes in cosmic ray ionisation arising from solar activity changes. Both the lower troposphere atmospheric electricity quantities are significantly increased at cosmic ray maximum(solar minimum),with a proportional change greater than that of the cosmic ray change

Illinois Precipitation Enhancement Program, Phase 1: Interim Report for 1 July 1972 - 31 July 1973

Division of Atmospheric Water Resources Management, Bureau of Reclamation, U.S. Department of Interior, Contract 14-06-D7197published or submitted for publicationis peer reviewedOpe

Road traffic pollution monitoring and modelling tools and the UK national air quality strategy.

This paper provides an assessment of the tools required to fulfil the air quality management role now expected of local authorities within the UK. The use of a range of pollution monitoring tools in assessing air quality is discussed and illustrated with evidence from a number of previous studies of urban background and roadside pollution monitoring in Leicester. A number of approaches to pollution modelling currently available for deployment are examined. Subsequently, the modelling and monitoring tools are assessed against the requirements of Local Authorities establishing Air Quality Management Areas. Whilst the paper examines UK based policy, the study is of wider international interest

Linking landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in a boreal stream network

Perturbations of stream ecosystems are often mediated by the terrestrial watershed, making the understanding of linkages between watersheds and streams essential. In this thesis I explore the connections between landscape characteristics, streamwater acidity and brown trout (Salmo trutta) distributions in Krycklan, a 67 km2 boreal stream network in northern Sweden. The study focuses on hydrochemical changes during the snowmelt-driven spring flood, a period of episodic acidity which is thought to place a restraint on acid-sensitive biota such as brown trout. pH ranged from 4.5-7.0 at different stream sites during winter baseflow, and declined by 0-2 pH units during spring flood. The magnitude of the pH drop at a given site was in large part controlled by changes in acid neutralizing capacity (ANC) and in natural organic acids associated with dissolved organic carbon (DOC). pH, ANC and DOC were all correlated with landscape characteristics such as proportion of peat wetlands, and stream hydrochemical response during spring flood could be explained by altered hydrological flowpaths through the catchment. The impact of acidity on brown trout distributions within the stream network was evaluated and compared to the apparent influence of other site and catchment-scale environmental factors. In situ bioassays demonstrated a strong relationship between spring flood pH and juvenile brown trout mortality, with a toxicity threshold at pH 4.8-5.4. In field surveys brown trout were not found at any sites which had pH <5.0 during spring flood, and were rare at sites which had pH <5.5 during spring flood, suggesting limitation by acidity for some streams. However, over the whole of the Krycklan stream network brown trout were more consistently associated with alluvial sediment deposits than with high pH or low inorganic aluminum concentrations. Acidity thus apparently influences trout distributions by setting a maximum potential distribution; within that potential distribution, actual dispersal is influenced by other factors, notably presence of physical substrate suitable for feeding and spawning habitat. Fulfilling chemical thresholds is therefore necessary but not sufficient for sustaining brown trout populations. In the context of environmental monitoring or stream restoration, consideration of physical habitat together with chemical conditions is advised

Towards a real-time microscopic emissions model

This article presents a new approach to microscopic road traffic exhaust emission modelling. The model described uses data from the SCOOT demand-responsive traffic control system implemented in over 170 cities across the world. Estimates of vehicle speed and classification are made using data from inductive detector loops located on every SCOOT link. This data feeds into a microscopic traffic model to enable enhanced modelling of the driving modes of vehicles (acceleration, deceleration, idling and cruising). Estimates of carbon monoxide emissions are made by applying emission factors from an extensive literature review. A critical appraisal of the development and validation of the model is given before the model is applied to a study of the impact of high emitting vehicles. The article concludes with a discussion of the requirements for the future development and benefits of the application of such a model

A global atmospheric electricity monitoring network for climate and geophysical research

The Global atmospheric Electric Circuit (GEC) is a fundamental coupling network of the climate system connecting electrically disturbed weather regions with fair weather regions across the planet. The GEC sustains the fair weather electric field (or potential gradient, PG) which is present globally and can be measured routinely at the surface using durable instrumentation such as modern electric field mills, which are now widely deployed internationally. In contrast to lightning or magnetic fields, fair weather PG cannot be measured remotely. Despite the existence of many PG datasets (both contemporary and historical), few attempts have been made to coordinate and integrate these fragmented surface measurements within a global framework. Such a synthesis is important elvinin order to fully study major influences on the GEC such as climate variations and space weather effects, as well as more local atmospheric electrical processes such as cloud electrification, lightning initiation, and dust and aerosol charging. The GloCAEM (Global Coordination of Atmospheric Electricity Measurements) project has brought together experts in atmospheric electricity to make the first steps towards an effective global network for atmospheric electricity monitoring, which will provide data in near real time. Data from all sites are available in identically-formatted files, at both one second and one minute temporal resolution, along with meteorological data (wherever available) for ease of interpretation of electrical measurements. This work describes the details of the GloCAEM database and presents what is likely to be the largest single analysis of PG data performed from multiple datasets at geographically distinct locations. Analysis of the diurnal variation in PG from all 17 GloCAEM sites demonstrates that the majority of sites show two daily maxima, characteristic of local influences on the PG, such as the sunrise effect. Data analysis methods to minimise such effects are presented and recommendations provided on the most suitable GloCAEM sites for the study of various scientific phenomena. The use of the dataset for a further understanding of the GEC is also demonstrated, in particular for more detailed characterization of day-to-day global circuit variability. Such coordinated effort enables deeper insight into PG phenomenology which goes beyond single-location PG measurements, providing a simple measurement of global thunderstorm variability on a day-to-day timescale. The creation of the GloCAEM database is likely to enable much more effective study of atmospheric electricity variables than has ever been possible before, which will improve our understanding of the role of atmospheric electricity in the complex processes underlying weather and climate