During an Inter-Regional Workshop on Improving Agrometeorological Bulletins in Barbados in October 2001, participants recommended that a dedicated web server be developed for distributing agrometeorological products from WMO members. Subsequently, an Expert Group Meeting on Internet Applications for Agrometeorological Products was held in Washington, DC, during May 2002, to discuss the practical steps needed to develop this web server. Discussions from this meeting led to the development of the World AgroMeteorological Information Service (WAMIS). WAMIS is a dedicated web server on which countries and organisations can place their agrometeorological bulletins and advisories. Provision of such a central location for agrometeorological information enables users to quickly and easily evaluate various bulletins and gain insight into improving their own bulletins. Also, these bulletins represent the expert knowledge of the individual countries and provide the possibility to assess extreme events and disasters in a historical perspective, especially when an archive of bulletins is present. Placement of agrometeorological bulletins on WAMIS also increases the visibility of the National Meteorological/Hydrological Services (NMHS). In March 2005, a tools and resources section was added to WAMIS to provide users with additional papers, links to software tools, Internet links, and other resources to help improving their agrometeorological bulletins and advisories and services.

During the International Cirrus Experiment (ICE), cirrus cloud properties over the North Sea were observed from local surface-based and aircraft instruments. In order to place these measurements in the context of the general space-time evolution of the cirrus systems and smaller cloud elements, Meteosat images were used to study the evolution of the clouds along their trajectories. The trajectories were established with techniques derived from those used to compute cloud motion winds from geostationary satellite images. Thermal infrared (IR) and water vapour (WV) channel tracking was performed to take advantage of the properties of each channel: better contrast of the clouds over the surface in the IR, and better discrimination of upper layers in the WV channel. Although long tracks, up to 60 hours, could be observed, they did not correspond to the same cirrus elements, or even the same system along the track. The evolution of the brightness temperatures along the tracked elements showed periodic fluctuations. The representativeness of these fluctuations in terms of cloud life cycle is discussed, as it may be related to the quality of the tracking.

Predicting rainfall along the New South Wales (NSW) coast is a major forecasting problem because of sharp gradients in rainfall amounts with the heaviest falls on the coastal fringe decreasing rapidly inland. On some occasions the rainfall pattern is less spatially coherent and consists of isolated maxima. Both rainfall patterns are associated with mesoscale coastal ridging. The first rainfall pattern arises from coastal ridging occurring in combination with an offshore trough. In the first case study presented here, a typical ridge-trough system was aligned parallel to the coast, and located just offshore, with the observed rainfall heaviest at the coast, decreasing rapidly from over 60 mm to near zero 30 km inland. The model captured well the southward temporal evolution of the maximum relative humidity values and rainfall. The second rainfall pattern occurs when shallow coastal ridging interacts with downdrafts from thunderstorm activity over the ranges to the west. The second case study was one in which convergence and condensation generated a quasi-stationary line of thunderstorms, resulting in flash flooding. The model precipitation rates and accumulations matched very closely those of the squall line, as revealed by radar precipitation intensities and the observed rainfall.

To obtain a high-resolution wind field and to model snow drift over complex topography, the Swiss Federal Institute for Snow and Avalanche Research (SLF) uses the atmospheric model ARPS (Advanced Regional Prediction System, University of Oklahoma). ARPS accesses horizontally homogeneous initial fields. Until recently, this model was driven by atmospheric soundings recorded at sites far away from the actual model domain. In order to optimise the initial conditions of ARPS and to provide the option of producing real forecasts, a new downscaling method has been developed, which can also be applied to other uses. Based on the vertical structure of the atmosphere produced by the operational mesoscale forecast model aLMo (Alpine Model, MeteoSwiss), an artificial sounding is created for a specified location within the ARPS grid. Some of the techniques applied include model bias adjustment (based on aLMo verification studies), the introduction of horizontal filters, the assimilation of surface observation data and the vertical displacement of the boundary layer, motivated by the distinct topographies of the ARPS and the aLMo model. The combination of the methods differs from parameter to parameter. This paper describes details of the downscaling technique and gives an example of the application of the method.

In tropical-equatorial environments, where weather has a high degree of variability, a reliable weather forecast is an essential decision-making tool. To achieve reliability and accuracy it is important to study both the climatological trends and the elements affecting the meteorological variables of the areas under analysis. A precise weather forecast is not enough, however. The way in which the information is presented to users in weather bulletins is also important. The users need to comprehend the forecasted meteorological synopsis and to draw relevant conclusions. In this case study a Medium Range Forecast model was used (NOAA Air Resources Laboratory MRF) to predict, in statistical form, the likely weather conditions. The verification of the weather forecast scored good results, especially in the shorter period (7 days), showing that this specifically designed weather bulletin was a reliable decision tool. In order to demonstrate the key role of the meteorological information to the decision-maker, an economic estimation of the weather forecasts was carried out.

There have been significant reforms in New Zealand of government management in general and of the science and transport sectors in particular. The impact of the reforms on the provision of meteorological services is discussed as an example of the application of the general reform thrust to a specialist technical area. The eventual outcome was the establishment of Meteorological Service of New Zealand Ltd (MetService) as a commercial company, trading in the weather forecasting market but remaining under Crown ownership. At the same time the National Institute of Water and Atmosphere (NIWA) was established. It includes the climatic responsibilities and much of the scientific research component of the former NZMS. It too operates commercially and is Crown owned. Unlike MetService, NIWA is not required to return a dividend to its owners. The procedures leading to the establishment of these new organisations, their mode of operation and their initial successful performance are described.

Owing to the decrease of stratospheric ozone during the southern spring (starting in September), the city of Punta Arenas (53.1°S, 70.9°W) and its surroundings are exposed to a high incidence of ultraviolet-B (UV-B) radiation during this period. Ozone denatures DNA, and prolonged exposure may cause skin carcinoma and cataracts. Consequently, there is great concern among the inhabitants of this region regarding the possible effects of long-term exposure to UV-B. In this work we apply and further develop a pilot study carried out in 1995 which looks at the simple operational method of forecasting ozone levels some 42 hours in advance. The method is based on the prediction of the 100 mb-temperature from ECMWF (European Centre for Medium-Range Weather Forecasts), which is well correlated with total column ozone levels. It allows the inhabitants of the Magallanes region to be alerted to potentially high incidences of UV-B radiation during the Austral spring.

In an effort to save money during the summer of 2003, Northern Illinois University (NIU) administrators instituted a four-day working week and stopped air conditioning buildings for the three-day weekends (Friday through Sunday). Shutting down the air conditioning systems caused a noticeable drop in electricity usage for that part of the campus that features in our study, with estimated total electricity savings of 1,268,492 kilowatt-hours or 17% of the average usage during that eight-week period. NIU's air conditioning systems, which relied on evaporative cooling to function, were sensitive to dew point levels. Greatest savings during the shutdown period occurred on days with higher dew points. An examination of the regional dew point climatology (1959–2003) indicated that the average summer daily dew point for 2003 was 14.9°C (58.8°F), which fell in the lowest 20% of the distribution. Based on the relationship between daily average dew points and electrical usage, a predictive model that could estimate electrical daily savings was created. This model suggests that electrical savings related to any future three-day shutdowns over summer could be much greater in more humid summers. Studies like this demonstrate the potential value of applying climatological information and of integrating this information into practical decision-making.

The NERC radar facility located near Aberystwyth (52.4° N, 4.1° W) was established for remote sensing of the structure and dynamics of the mesosphere, stratosphere and troposphere; hence the name MST radar. The facility records scatter and reflection from metre-scale irregularities in refractive index produced by atmospheric waves and turbulence. The measurement of the three-dimensional wind field at tropospheric and lower stratospheric heights represents the primary capability of the facility and is expected to be particularly useful in short-range local weather forecasting operations. At the same time, the temporal and height resolution achievable lend themselves to studies of smaller-scale, time-varying phenomena, such as waves and turbulence. Particular attention has been paid to the characteristics and vertical propagation of mountain waves and inertia-gravity waves, and estimates made of the vertical flux of horizontal momentum associated with such waves, known to play a significant role in the large-scale atmospheric circulation. The turbulence associated with the dissipation of these waves, and also generated in the vicinity of jet streams, has also been examined. Quasi-specular reflection of radar waves associated with changes in temperature gradients has helped monitor the height and sharpness of the tropopause and also the structure of frontal zones. The technical capabilities of the facility and the continuity of data provided by its all-weather and extended operation have been shown to be well suited to both mesoscale meteorological and research applications.

Precipitation enhancement over a low coastal hill in winter is demonstrated for particular associations of synoptically determined onshore airflow and local geography encountered over south-eastern Newfoundland. Four such cases, involving a mixture of pre-warm-frontal precipitation types at surface temperatures just below freezing, are analysed using comparative surface gauge records from sites at the coast and hill summit and detailed volume scan data from a Doppler radar. Whilst precipitation at the hill summit and upwind coast was of similar overall duration in each case, the surface rates on the hilltop exceeded those at the coast by 1.0-4.0 mm h-1 during different stages of the events. Analysis of the Doppler reflectivity patterns reveals that intensities are especially enhanced near the windward hill crest, supporting the observed association of greatest enhancement with a strong local upslope wind component exceeding 20 m s-1. In the majority of these cases the enhancement is maintained primarily by the ‘seeder-feeder’ mechanism, which appears to be accelerated during precipitation transitions and with the surface warm front 120-150 km distant; however, a preliminary phase of enhancement due to topographically induced uplift of stable pre-frontal air is also recognised in one case.

The Institute of Meteorology and Water Management (IMWM) manages the national hydrological-meteorological service, which maintains the measurement network, processes data, and issues warnings, reports and announcements. There are five divisions of IMWM located around Poland. Each division includes numerous stations and scientific-research departments. The data gathered, processed and analysed by IMWM are space-related; therefore spatial information systems are indispensable for data processing and visualisation. In this paper we discuss the development of the model for GIS applications in the national hydro-meteorological service in Poland (IMWM).

Food insecurity represents one of the main indicators of the poverty level of a country and can breed a strong dependence on foreign aid with a strong slowdown of the national economy. African arid and semi-arid areas are characterised by food precariousness and their agricultural activity is strongly dependent on the extreme climatic conditions that affect the available water supply. This situation has led to the need to develop new tools for the prediction and the management of crisis. The characterisation of climate and the identification of anomalies, the monitoring of weather conditions and their influence on crops, short and medium range weather forecasts and long-term climate predictions are among the most powerful tools to predict, in as short a time as possible, crises due to the absence or delay of rainfall season. Meteorological information can also be used as an input to agrometeorological models applied for crisis prevention or for its management during the growing season when the crops are already present. In this paper, a review of these tools is made and some operational products presented.

With the aid of a generalised frontogenesis vector and an expanded Q-vector diagnosis, the frontogenetic and frontolytic effects in numerical model analysed winds are determined for the case of a typical cyclogenesis over the North Atlantic. These effects, when occurring in the geostrophic part of the flow, give rise to circulations transverse to the frontal zone and the resulting vertical motions are of importance for the dynamics of the cyclone. The forcing of the transverse circulatory motions, which is given by Q-vector divergences across the isotherms, is computed and compared with the forcing resulting from divergences along the frontal zone. The analyses for 850 and 500 hPa show that frontogenesis dominates at the beginning of the cyclogenesis as well as at its final stage, whereas in the meantime different patterns result for both levels. A significant feature in this case was the development of a new frontal zone north of the deepening low through interaction with the parent low further north. Comparison of the different parts of the omega forcing reveals that the forcing through Q-vector divergences along the isotherms is the stronger one during the mature stage, but that the transverse circulations contribute significantly to the total forcing. This is especially true for the cold front in the lower troposphere and for the newly developing frontal zone in both levels. At the final stage the influence of the transverse circulatory forcing is even more important and determines to a great extent the shape of the total forcing. The outcome of this study corresponds very well with the findings from other investigations and with the fields derived from a vortex model.

Practical monitoring of the amount of salt spread on the road surface for de-icing purposes is technically difficult, especially if it has to be done in a commercially viable way. Possible solutions to this problem are discussed. As it has become customary to refer to the freezing temperature of a salted road, the physical meaning of such a temperature is scrutinised. It turns out that the meaning and the definition of freezing temperature are not clear, and that it also does not have the significance that is often associated with it. Some experimental results of salt measurements on a road are presented.

Limited meteorological monitoring networks provide insufficient information for determining the suitability of a specific location for an airport runway. These data limitations are compounded by the constraints imposed by the terrain itself. Clusters of small islands (archipelagos) generally lack dense meteorological monitoring networks, while the land–water distribution induces different meteorological regimes on neighbouring islands.

In this paper we present an integrated methodology to study the meteorological characteristics of potential runway sites on a medium-size island in the Aegean Sea in Greece. The methodology is based on studying the three scales of motion: (i) the synoptic scale, through a synoptic classification scheme, (ii) the mesoscale circulations with the aid of a Computational Fluid Dynamics (CFD) model, and (iii) micro-scale characteristics of each potential runway site through in-situ inspections.

The difficulties of forecasting for flights of hot-air balloons and small airships are discussed, as well as methods which may be used to improve forecast accuracy. The low-wind-speed requirements and details of weather forecasts required for safe flight are near the limits of accuracy of the forecaster, even when aided by computer models. Preparations for the briefing of balloon pilots need to be carefully undertaken.

The UK Meteorological office introduced a new bogussing scheme for tropical cyclone (TC) motion prediction in its global model in October 1994 after a series of tests. Before the operational implementation of this scheme, a 19-day period (in August and September 1994) was selected during which both the new and the old schemes were run operationally in parallel for a total of 12 TCs in three ocean basins. Comparisons between the forecast errors of the schemes demonstrated the superiority of the new scheme at all forecast time periods (Heming et al., 1995). This paper presents the results of an investigation into the possible reasons for the improved predictions by the new scheme during this trial period. All three factors of the new scheme (an improved initial positioning of the TC, an imposed steering flow derived from the past 6-h motion of the TC and an empirical vortex structure determined from actual observations and TC warning bulletins) are found to contribute towards the improvement. In particular, a good initial position together with an appropriate steering produce a much better 24-h forecast. For the 48- and 72-h forecasts, the steering flow remains an important factor and the contribution of the vortex structure also becomes significant in some cases. The steering flow appears to be the most crucial factor in determining the accuracy of the model predictions.

Artificial Neural Networks (ANNs) that were originally proposed to model brain functions mathematically are now being used in many branches of research, including the atmospheric sciences. The main contribution of this paper is the development of ANN to identify the presence of thunderstorms (and their location) based on microwave measurements from all five AMSU-B frequencies and on surface observations over Iran (45–65°E, 25–45°N). From the surface observations, the position of each of the different meteorological events (thunderstorm, heavy rain, rain, light rain, snowfall and clear sky) is located in AMSU-B images. An area around this position with roughly the same brightness (visually) is selected. Then the brightness temperatures (TBs) of a few randomly selected pixels from this area are noted. In all, there were 560 pixel-points, over 20 passes of AMSU-B, in these selected areas. It is found that the thunderstorms are related to image features that are bright in all of the five-frequency images (i.e. have low TB), as expected.

The architecture of the neural network that was finally selected for identifying thunderstorm events (as against other reported events), after a series of trial and error for the best accuracy, was achieved using the four-layered Feed-Forward Artificial Neural Network (FFANN) with five nodes in input, two hidden layers with four nodes each, and one node in the output layer. In the ANN output, the thunderstorms clustered clearly away from other phenomena. ANN gave more correct thunderstorm recognition (96.7%), whereas the discriminant analysis gave 95.3% correct recognition without clear separation between the two classes.

Economic impacts from the near record warm and snow-free winter of 2001–2 in the United States were assessed to ascertain their dimensions and relevance to issues like climate prediction and climate change. Unusual impacts resulted and embraced numerous sectors (heating/energy use, construction, tourism, insurance, government, and retail sales). Many outcomes were gains/benefits totalling $19.6 billion, with losses of $8.2 billion. Some economists identified the sizable positive impacts as a factor in the nation's recovery from an on-going recession stemming from the terrorist attacks on 11 September 2001. Understanding the impacts of such a winter reveals how climate predictions of such conditions could have great utility in minimising the losses and maximising the gains. The results also have relevance to the global warming issue since most climate models project future average winter temperature and snowfall conditions in the United States to be similar to those experienced in 2001–2.

The Australian Bureau of Meteorology has been providing weather services for Australian Antarctic expeditions since the first expedition of 1947 and the forecasting services have been gradually evolving over the decades. However, with the advent of high bandwidth communications into Antarctica in the early 1990s there has been, for the first time, access to high-resolution satellite imagery, numerical model data and global observational datasets. Over the past seven years locally designed and developed forecast systems have matured and now provide the Antarctic forecaster with a comprehensive suite of systems to assist in the timely and accurate provision of aviation, marine and terrestrial forecasts. The ease with which these data may be manipulated, displayed and interpreted is expected to have a positive impact on the quality of forecasts provided to the Antarctic user.