Showing papers on "Weather station published in 2001"

Impact of Rainfall on the Productivity of Highway Construction

Abstract: Heavy rainfall often leads to complete suspension of highway construction due to saturated and unworkable soil conditions. Therefore, quantifying the impact of rainfall on the productivity of highway construction is essential in preparing realistic schedules and cost estimates for the preconstruction stage and in analyzing weather-related claims for the postconstruction stage. This paper presents a decision support system for quantifying the impact of rainfall on productivity and duration of common highway construction operations, namely: earthmoving, construction of base courses, construction of drainage layers, and paving operations. The system incorporates a knowledgebase and a database. The knowledgebase includes if/then type rules, acquired from experts in highway construction operations, and the database contains hourly records of weather parameters from the closest weather station to the construction site. The system, named WEATHER, is a software system that provides user-friendly interface, including menus, dialog boxes, and graphical capabilities to facilitate data input and output.

The importance of the air temperature variable for the snowmelt runoff modelling using the SRM

Abstract: Runoff regimes in most northern basins are controlled by the melting snow cover. A common method for evaluating runoff consists in correlating ambient air temperature and recorded hydrometric gauge values. The air temperature is the principal variable to estimate the importance of the melting of the snow cover when using a global conceptual model such as the snowmelt runoff model (SRM). The temperature, which is often only measured at one weather station, must be extrapolated to the whole basin according to some kind of lapse rate. This extrapolation often assumes that air temperature is representative for a wide region, which is often not the case. The estimation of temperature values is critical, especially for large basins where the surface processes are largely influenced by a forest cover. This project has two objectives: (1) applying a mostly high mountain SRM to the Batiscan River Basin, in the Province of Quebec, an area occupied by a forest with a rolling hill topography; (2) investigate the impact of the extrapolation strategy for estimating temperature values and its importance in the runoff modelling. A statistical comparison between the different modelling attempts was performed. This allowed us to obtain a sensitivity analysis of the snow runoff modelling in relation to the extrapolation of the temperature values. Our results showed that the weather station, used to perform the runoff modelling, should be located in the most representative land cover of the study area. Otherwise, the values of a synthetic regional weather station were more reliable for the modelling. Finally, before pursuing any snowmelt modelling with the SRM, the temperature values must be evaluated based on the location of the weather station to see if they are representative of the total study area. Copyright © 2001 John Wiley & Sons, Ltd.

Cellular weather station and computer system using the public cellular data telephone system and internet for controlling irrigation and method of use

Abstract: A system and method for accessing and displaying weather information are shown. A weather station (102) collects weather information data from sensors (108-114) using a collection program and assembles the data as a data string in a memory. A station access system (140) is used to call the weather station through the Internet (150) and a wireless cellular digital packet data system (154). The weather station downloads the weather data string to a data base (164). A user contacts the access computer through the Internet using his personal computer (170) to ask for the weather information. The information is compiled from the data base and transmitted to the user's display (172) over the Internet. A user such as a farmer can also supply the system with his particular field and crop conditions and the system will apply the conditions to the weather information and return customized crop production and control information to the farmer over the Internet.

Temperature data for phenological models.

Abstract: In an arid environment, the effect of evaporation on energy balance can affect air temperature recordings and greatly impact on degree-day calculations. This is an important consideration when choosing a site or climate data for phenological models. To our knowledge, there is no literature showing the effect of the underlying surface and its fetch around a weather station on degree-day accumulations. In this paper, we present data to show that this is a serious consideration, and it can lead to dubious models. Microscale measurements of temperature and energy balance are presented to explain why the differences occur. For example, the effect of fetch of irrigated grass and wetting of bare soil around a weather station on diurnal temperature are reported. A 43-day experiment showed that temperature measured on the upwind edge of an irrigated grass area averaged 4% higher than temperatures recorded 200 m inside the grass field. When the single-triangle method was used with a 10°C threshold and starting on May 19, the station on the upwind edge recorded 900 degree-days on June 28, whereas the interior station recorded 900 degree-days on July 1. Clearly, a difference in fetch can lead to big errors for large degree-day accumulations. Immediately after wetting, the temperature over a wet soil surface was similar to that measured over grass. However, the temperature over the soil increased more than that over the grass as the soil surface dried. Therefore, the observed difference between temperatures measured over bare soil and those over grass increases with longer periods between wettings. In most arid locations, measuring temperature over irrigated grass gives a lower mean annual temperature, resulting in lower annual cumulative degree-day values. This was verified by comparing measurements over grass with those over bare soil at several weather stations in a range of climates. To eliminate the effect of rainfall frequency, using temperature data collected only over irrigated grass, is recommended for long-term assessment of climate change effects on degree-day accumulation. In high evaporative conditions, a fetch of at least 100 m of grass is recommended. Our results clearly indicate that weather stations sited over bare soil have consistently higher degree-day accumulations. Therefore, especially in arid environments, phenology models based on temperature collected over bare soil are not transferable to those based on temperature recorded over irrigated grass. At a minimum, all degree-day-based phenology models reported in the literature should clearly describe the weather station site.

Standardisation of temperature observed by automatic weather stations.

Abstract: Daily mean, maximum and minimum surface airtemperature data were gathered from a network ofautomatic weather stations (AWS) within the Moor HouseNational Nature Reserve in northern England. Five AWSwere installed next to the official EnvironmentalChange Network weather station at Moor House. Datawere compared graphically and correction constantswere calculated to adjust data from each AWS to thestandard of the official station by optimising theconcordance correlation coefficient. Each correctedstation was re-located next to one of five in-situstations in and around the reserve, allowingcorrection of all temperature sensors to a commonstandard. The mean error associated with measureddaily mean, maximum and minimum temperature for eachsensor does not exceed ±0.2 K. The procedurequantifies a source of systematic measurement error,improving the identification of spatial temperaturedifferences between stations.

Enhancements to the CLIGEN Weather Generator for Mountainous or Custom Applications

Abstract: The Water Erosion Prediction Project (WEPP) model is a state-of-the-art soil erosion model applicable to a wide range of vegetation, soil, and climatic conditions. The CLIGEN weather generator is distributed with WEPP. The CLIGEN database contained some errors in the data and did not include many climate stations in mountainous areas where most forests are located and where climate is highly variable. Errors in the database were identified and corrected. The database was expanded from 1,100 stations to more than 2,600. In addition, the ability to modify the statistics for a climate station has been developed to allow users to enter their own weather station statistics into a web-based computer interface. Users can enter specific values, change existing values by a percentage, modify the annual amount, or adjust temperatures with elevation. The PRISM monthly precipitation database was incorporated into the interface to aid users in predicting climates at remote sites. The designated changes are made to an existing CLIGEN parameter file to generate a modified climate file. The modified climate file may be selected for use with a Forest Service WEPP interface, or it may be used to generate a climate file for use with the WEPP model. The enhancements can be accessed from a web site.

An investigation of winter nocturnal air and road surface temperature variation in the West Midlands, UK under different synoptic conditions

Abstract: This study considers night-time urban air and road surface temperature variations under different synoptic weather conditions. Five years of winter weather data from a single weather station were classified into groups with similar air-mass characteristics. Using a two-stage process of principal components analysis followed by cluster analysis, the resulting clusters were used to sort paired air and road-surface temperature observations recorded at 2100hr from the West Midlands road weather information network into days with similar meteorological controls. The six resulting clusters have good between-group variation and feature a dominant wind direction. The results show that the difference between air and road surface temperatures is significant except during strong westerly conditions. Days featuring clear and anticyclonic weather showed the greatest between-site variation and evidence of the urban heat island effect. Under these conditions, road surface temperatures were warmer than the air - the opposite of what one would normally expect in rural areas. Those days with wet and windy weather were found to have the least between-site variation, excepting that due to altitude. The presence of a high vapour flux in the urban environment literally dampens the temperature response.

Global Surface Solar Energy Anomalies Including El Niño and La Niña Years

Abstract: This paper synthesizes past events in an attempt to define the general magnitude, duration, and location of large surface solar anomalies over the globe. Surface solar energy values are mostly a function of solar zenith angle, cloud conditions, column atmospheric water vapor, aerosols, and surface albedo. For this study, solar and meteorological parameters for the 10-yr period July 1983 through June 1993 are used. These data were generated as part of the Release 3 Surface meteorology and Solar Energy (SSE) activity under the NASA Earth Science Enterprise (ESE) effort. Release 3 SSE uses upgraded input data and methods relative to previous releases. Cloud conditions are based on recent NASA Version-D International Satellite Cloud Climatology Project (ISCCP) global satellite radiation and cloud data. Meteorological inputs are from Version-I Goddard Earth Observing System (GEOS) reanalysis data that uses both weather station and satellite information. Aerosol transmission for different regions and seasons are for an 'average' year based on historic solar energy data from over 1000 ground sites courtesy of Natural Resources Canada (NRCan). These data are input to a new Langley Parameterized Shortwave Algorithm (LPSA) that calculates surface albedo and surface solar energy. That algorithm is an upgraded version of the 'Staylor' algorithm. Calculations are performed for a 280X280 km equal-area grid system over the globe based on 3-hourly input data. A bi-linear interpolation process is used to estimate data output values on a 1 X 1 degree grid system over the globe. Maximum anomalies are examined relative to El Nino and La Nina events in the tropical Pacific Ocean. Maximum year-to-year anomalies over the globe are provided for a 10-year period. The data may assist in the design of systems with increased reliability. It may also allow for better planning for emergency assistance during some atypical events.

Evaluation and Enhancement of the CLIGEN Weather Generator

Abstract: Stochastic weather generators are often employed with process-based soil erosion prediction models. Longterm observed weather station statistics (precipitation, temperature, etc.) can be used to provide a daily series of temperature, precipitation, solar radiation, and wind parameters needed by an erosion model in its calculations for evapotranspiration, plant growth, soil frost and thaw development, snow melt, infiltration, runoff, and soil erosion. The Water Erosion Prediction Project (WEPP) erosion model typically uses the CLIGEN weather generator to provide the daily climatic inputs that drive its hydrologic and erosion processes. This presentation describes recently identified problems with CLIGEN and its weather station database, as well as enhancements to improve the generator program and supporting database.

Impact of local climate variability on crop model estimates in the south-east of France

Abstract: Most crop models use climatic data recorded from weather stations located on standard surfaces such as grass. These environmental conditions represent meso-climates typical of the region but often do not reflect the crop micro-climate. The aim of this paper is to show the effect of the envi- ronment surrounding the weather stations on the variability of climatic data and to estimate the impact of these variations on different outputs of crop models (crop cycle length, yield, irrigation and quantities of fertilizer). The crop model STICS was used with different management strategies. Sim- ulations were performed using climatic data measured at 5 meteorological stations surrounded by different environments (wet grassland, dry area, wheat, soybean and irrigated wheat) in a small agri- cultural region in the south-east of France. The distances between the stations ranged from 3 km to a maximum of 10 km. The region is flat and has 1 weather station of the conventional national synop- tic network. The measurements show that, even at such a small regional scale, the spatial variability due to the environment surrounding a weather station is important and should be taken into account. Significant discrepancies were observed both for yield and irrigation, as well as crop cycle length, according to the climatic data considered. Differences in soil moisture produce the greatest differ- ences in air temperature between the weather stations and, consequently, the greatest discrepancies between the outputs of the crop models.

Effects of Urbanization on Radiation Fog in Xishuangbanna Area

Abstract: Using the data from Jinghong and Damenglong weather station, we analyzed the reasons of radiation fog reducing in XishuangBanna, Yunnan province. The results show that the climatic features of annual foggy day, mean annual temperature, mean annual humidity, mean annual maximum temperature and mean annual minimum temperature etc of Jinghong and Damenglong were very similar from 1960 to 1984. However. after 1985, the variations of foggy day and mean annual humidity in Jinghong and Damenglong were different due to urban construction and natural climatic variation. The urbanization plays the very important role on radiation fog reducing in the area

A Field test of the Wind Erosion Prediction System

Abstract: Field data need to be collected to test wind erosion models under a broad range of climate, soil, and management conditions. The objective of this study was to test the USDA-ARS Wind Erosion Prediction System (WEPS) for a field with winter wheat plants in a modest amount of flat residue. A 600 m by 415 m field was selected near Burlington, CO, USA. Big Spring Number Eight (BSNE) samplers were used to measure wind blown sediment flux and automated devices (Sensits) for continuous detection of saltation. A weather station recorded relevant meteorological data. Detailed measurements of the field surface were taken on three dates. The experiment was conducted from 25 November, 2000 through 12 April, 2001. One dust storm occurred during this experimental period, with a net field sediment loss of 0.06 kg/m 2 . Spatial variability of sediment discharge was high and could be explained by spatial differences in field conditions. WEPS overestimated the protective power of small wheat plants. It needs a provision to account for standing biomass that is not uniformly spaced, such as wheat plants in the field. Wind erosion (and WEPS) is very sensitive to soil surface water content, which is difficult to measure. Albedo is a good indicator of soil wetness right at the soil surface, but additional research is needed to use albedo for quantifying soil surface water content.

Method and facilities for transmitting and receiving regional, up-to-date weather information and weather reports, uses LW RDS consisting of LW transmission station, a receiver and PWS weather station

Abstract: Weather data from sources like the Royal Dutch Meteorological Institute is passed on to an LW station with a data server and LW transmitter along a data transmission path. Data is compiled as data transmission protocols in a data server, then beamed out by the LW transmitter with available regional weather details, RDS protocols, details on type of message, transmission times and very exact clock times. A PWS receiver calls up such information selectively. Weather station consists of an LW data receiver, power management, a display device with special weather characters lines of text and a processor with operating elements. Regional weather information and weather reports can be selectively requested via these operating elements.

Wind speed simulation using double fourier transformation

Abstract: Understanding the behavior and characteristics of wind speed will help to efficiently harness the wind's power. By simulating wind speed behavior, wind turbines can be matched to each energy application to provide a renewable energy resource capable of supplementing utility power. Annual mean wind speed can be used to estimate potential energy production for wind power, but this does not give an indication of the periodic variation in wind speed. In areas of West Texas, wind speed varies periodically both diurnally and seasonally. As a result, it can be characterized by a two-dimensional Fourier transformation. This research used a double Fourier series developed by Harbaugh and Merriam (1968) applied to a two-dimensional wind surface grid. Hourly wind speed data were collected from a weather station in St. Lawrence, Texas, to develop a wind surface map. The model was calibrated using data from 1992 and validated using data from 1995 and 1996. The mean absolute error (MAE) for the 288-point wind speed grid was 0.226, 0.799, and 0.707 m/s for 1992, 1995, and 1996, respectively. These errors fall within 6%, 26%, and 22% of the absolute mean wind speed for 1992, 1995, and 1996, respectively. Finally, the probability distribution providing best fit to the residuals was determined. Most frequently, the residuals were best fit by the normal distribution.