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A portable meteorology station capable of measuring various atmospheric parameters (mainly ambient temperature, relative humidity, atmospheric pressure, wind speed and direction) was designed and built. The physical quantities were converted to electrical signals using suitable sensors. These signals were then processed and transferred to digital values to be stored in suitable memories. A nuclear radiation alarm system was also built, on the main board, to monitor the nuclear radiation releases levels. The system consists of three main parts: control board, data acquisition board and signals conditioning board. The overall system is controlled by a BASIC-8052 micro-controller.
A wake vortex warning system (WVWS) has been developed for Frankfurt Airport. This airport has two parallel runways which are separated by 518 m, a distance too short to operate them independently because wake vortices may be advected to the adjacent runway. The objective of the WVWS is to enable operation with reduced separation between two aircraft approaching the parallel runways during appropriate wind conditions. The WVWS applies a statistical persistence model to predict the crosswind within a 20-minute period. One of the main problems identified in the old WVWS is discontinuity between successive forecasts. These forecast breakdowns were not acceptable to air traffic controllers. At least part of the problem was related to the fact that the forecast was solely based on the prediction of crosswind. A new method is developed on the basis of 523 days of sonic anemometer measurements at Frankfurt Airport. It is demonstrated that the prediction of the horizontal wind vector avoids these difficulties and significantly improves the system's performance.
Although numerical weather prediction (NWP) models provide an objective forecast, poor representation of local topography and other features in these models, necessitates statistical interpretation (SI) of NWP products in terms of local weather. The Perfect Prognostic Method (PPM) is one of the techniques for accomplishing this. At the National Center for Medium Range Weather Forecasting, PPM models for precipitation (quantitative, probability, yes/no) and maximum/minimum temperatures are developed for monsoon season by using analyses from the European Centre for Medium-Range Weather Forecasts. The SI forecast is then obtained by using these PPM models and output from the operational NWP model at the Center. Direct model output (DMO) obtained from the NWP model and the SI forecast are verified against the actual observations. The present study shows the verification scores obtained during the 1997 monsoon season for 10 locations in India. The results show that the SI forecast has good skill and is an improvement over DMO.
There is an increasing need for more rigorous and more broadly based determination of the economic value of meteorological services as an aid to decision-making on the appropriate level of funding to be committed to their provision at the national level. This paper develops an overall framework for assessment of the economic value of meteorological services based on the recognition that most national meteorological infrastructure and services possess the non rival properties of public goods. Given this overall framework for determination of both total and marginal benefits, four main methodologies appropriate for use in valuation studies - market prices, normative or prescriptive decision-making models, descriptive behavioural response studies and contingent valuation studies - are outlined and their strengths and limitations described. Notwithstanding the methodological limitations and the need for a much more comprehensive set of studies for the various application sectors, it is clear that the actual and potential benefits to individuals, firms, industry sectors and national economies from state-of-the-art meteorological and related services are substantial and that, at this stage, they are inadequately recognised and insufficiently exploited in many countries.
Different options for funding the provision of meteorological services and for charging for the information provided are described and evaluated. The basic infrastructure and general forecasts and warnings have public good properties of non rival consumption and high costs of exclusion. For these, direct government funding and free provision to all are favoured. Value added meteorological services for use by small groups of specialised users have mixed good properties, and in some cases private good properties. In this case, setting fees at marginal incremental costs for value added services is favoured for reasons of efficiency and practicality. The other options considered include government funding with zero price, and loading user fees for a contribution to funding the public good supply costs.
For forecasting strong dust storms in the central and western areas of the Inner Mongolia Autonomous Region an objective discrimination approach has been developed. The 37 strong dust-storm events that occurred in this area during the last 40 years have been classified into four circulation patterns. Using the method suggested by Saaty (1996), a priority relationship matrix was set up and the discrimination function was then established. Depending on the function values, a judgement is then made about whether the real-time situation belongs to any of the four patterns and, if so, to which one. If there is a match, then this typical event can be used as a basis for forecasting a strong dust storm. The successful application of this approach is demonstrated using results from 1998 and 2000.
A flood study of the Himalayan rivers has been attempted on the basis of gauge/discharge data from 27 sites on major tributaries of the Ganga between 1986 and 1999. This study has shown that the Ghaghra, Gandak, and Kosi are the most important tributaries of the Ganga and their flood waters should be harnessed for developmental purposes to save the Indo-Gangetic plains from the recurrence of yearly floods. It was also found that some of the sites on these rivers have recorded floods more than 100 to 150 times during the 14-year period.
An operational system for diagnosing probability of convective development and structure from NWP model outputs over the British Isles has been developed in the Met Office. The system originated as a research and development project and so for historical reasons is now known as the Convection Diagnosis Project (CDP). The system takes account of expected model errors in temperature and humidity and allows for forcing from sub-grid scale mechanisms on a 1-km scale that are important for mid-latitude convection. A NWP convection scheme is used to determine grid-mean parameters from a range of forcings according to probability of occurrence. The grid-mean values are then used in a simple and variable object-oriented life-cycle model of a convective cloud to diagnose shower structure and expected movement. Using the life-cycle model, a range of probabilistic forecast outputs are produced four times a day from T+6 to T+36 hours ahead for individual grid squares and for larger pre-defined regions. Case studies and rigorous objective verification, making use of an automatic method for identifying convective cloud from radar and satellite data, have shown that the CDP outputs complement the standard NWP outputs and can provide additional useful information in a forecasting environment.
Measurements and estimates of evaporation have been routinely carried out for over a century. In the United Kingdom the most well-known method of estimating evaporation and its derivatives such as soil moisture deficit (SMD) is the Meteorological Office Rainfall and Evaporation Calculation System (MORECS) which is based on the Penman-Monteith equation. Direct measurements of evaporation have become less common in recent years. A comparison of measurements and estimates of evaporation and SMD at a single site and over two catchment areas is presented in this paper. Measurements of actual evaporation from a grassed lysimeter have been achieved for the period 1995-98 and they agree well with catchment losses over the same time period in two natural catchments, the Upper Brue and Upper Cary. In contrast to this, MORECS estimates of actual evaporation are different by an average of +20% for the Upper Brue catchment and +27% for the Upper Cary catchment. The largest difference is nearly +40% for the Upper Cary catchment. Similarly, there are substantial differences in the estimates of SMD, often up to 50 mm. When local rainfall is used together with MORECS estimates of potential evaporation the discrepancy is reduced but significant differences remain during much of the growing season, although improvements do occur. The results from this paper will be of great importance to growers, water resource planners, engineers who give flood warnings, and to river flow modellers.
A weather radar and processing system has been developed in conjunction with North West Water Ltd., a water utility responsible for the supply of potable water and the treatment of wastewater in the north-west of England. The primary objective has been to develop a radar system which can produce accurate and reliable quantitative estimates of rainfall at a temporal and spatial resolution commensurate with the requirements of urban drainage system modelling. This paper describes procedures for removing ground clutter and adjusting radar estimates of rainfall (using the Probability Matching Method). An archive of stratiform rainfall event data has supported an objective assessment of the radar data quality using a dense gauge network and simulated flow hydrographs for an urban drainage system. The results indicate that the adjusted radar data are of comparable accuracy to the dense raingauge data and are therefore of sufficient accuracy to be used for the management of water resources within an urban environment. The data processing and adjustment procedures have been incorporated into a real-time data processing and display software package (ARTIST) which is briefly described in the paper.
Meteorologists who work in the energy commodities market continue to investigate ways to enhance
predictions of seasonal temperature anomalies using oceanic/atmospheric indices. This study examines
the relationship of three climate indices - ENSO (El Niño/Southern Oscillation), PNA (Pacific North
American) and NAO (North Atlantic Oscillation) - to heating degree day (HDD) totals accumulated
in 11 cities in the Midwest and northeastern United States, to determine which, if any, has predictive
power. The data covers the 48-year period between 1951/52 and 1998/99, and focuses on two periods
either side of 1 January (i.e. the winter months of October-December and January-April). The index
most strongly related to the HDD anomalies during both winter periods was NAO. NAO values were
negative for cold (above-average HDD) anomalies occurring prior to and after 1 January, while the
NAO values were generally positive during warm (below-average HDD) anomalies. During cold
anomalies, the PNA values were generally positive in the three months before 1 January and negative
afterwards, indicating that different atmospheric teleconnection patterns cause similar temperature
anomalies in these regions. The relationship between the equatorial Pacific sea-surface temperatures
(SST) data and temperature anomalies was the weakest. Confidence in these relationships increased
when the extreme HDD anomaly years were examined. These results indicated that the relationships of
climate indices to HDD anomalies exist and that these would be useful in developing and improving
seasonal predictions for business applications.
A cold air outbreak occurred in the third week of April 1999 in southern Brazil. A synoptic study of this rare event is undertaken. A surface high pressure cell in the Pacific Ocean off the coast of Chile slowly built up and moved eastward on 14 April. It started crossing the Andes, acquiring the characteristic shape of a bean on 15th, and separated into two cells later in the day. The cell on the lee side of the mountains moved gradually northwards over central South America affecting northern Argentina, Paraguay, Uruguay, Bolivia and southern Brazil. The temperature fell 15°C in the state of Mato Grosso (about 15°S). In southern Brazil temperatures below freezing were registered in some places on the 17th and 18th and frost occurred in many states. There was snowfall in the uplands of Santa Catarina on the 17th, and such an early snow had not been recorded for 30 years. Baroclinic synoptic wave intensification followed by surface low development in association with a cut-off low formation in the middle and upper troposphere were responsible for strong surface southerlies over Argentina on the 16th and 17th. Cold air advection by the southerlies in the eastern sector of the high-pressure centre was responsible for the northward projection of the high pressure cell east of the Andes. The whole event was well predicted by the Centro de Previsão de Tempo e Estudos Climáticos/Instituto Nacional de Pesquisas Espaciais (CPTEC/INPE) operational global and regional models with lead times of 120 and 60 hours respectively