| 1. |
- Bhowmik, Avit Kumar, et al.
(författare)
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Representativeness impacts on accuracy and precision of climate spatial interpolation in data-scarce regions
- 2014
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Ingår i: Meteorological Applications. - : Wiley-Blackwell. - 1350-4827 .- 1469-8080. ; 22, s. 368-377
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Tidskriftsartikel (refereegranskat)abstract
- Data scarcity is a major scientific challenge for accuracy and precision of the spatial interpolation of climatic fields, especially in climate-stressed developing countries. Methodologies have been suggested for coping with data scarcity but data have rarely been checked for their representativeness of corresponding climatic fields. This study proved that satisfactory accuracy and precision can be ensured in spatial interpolation if data are satisfactorily representative of corresponding climatic fields despite their scarcity. The influence of number and representativeness of climate data on accuracy and precision of their spatial interpolation has been investigated and compared. Two precipitation and temperature indices were computed for a long time series in Bangladesh, which is a data-scarce region. The representativeness was quantified by dispersion in the data and the accuracy and precision of spatial interpolation were computed by four commonly used error statistics derived through cross-validation. The precipitation data showed very little and sometimes null representativeness whereas the temperature data showed very high representativeness of the corresponding fields. Consequently, precipitation data denoted scarcity but the temperature data denoted sufficiency regarding the required number of data for ensuring satisfactory accuracy and precision for spatial interpolation. It was also found that with the available data, accurate and precise precipitation surfaces can be produced only for representative synoptic spatial scales whereas such temperature surfaces can be generated for the regional scale of Bangladesh. It is highly recommended that the rain-gauge network of Bangladesh be increased or redistributed for computing representative regional precipitation surfaces.
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| 2. |
- Hannachi, Abdelwaheb
(författare)
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Intermittency, autoregression and censoring : a first-order AR model for daily precipitation
- 2014
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Ingår i: Meteorological Applications. - : Wiley. - 1350-4827 .- 1469-8080. ; 21:2, s. 384-397
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Tidskriftsartikel (refereegranskat)abstract
- Daily precipitation is investigated in this study in terms of simple first order autoregressive models. The methodology is based on combining theory from censored processes with continuous autoregressive models to model intermittent phenomena. The choice of short-memory autoregressive models is corroborated further by recent findings on scaling properties of daily precipitation records. The theory and application to synthetic models are presented. The methodology is then applied to Northern Ireland Armagh Observatory daily precipitation for the period 1950-2001 for each month. Both zero- and non zero-mean processes are considered. The analysis indicates that the model parameters do capture seasonality where, for example, the autocorrelation co-efficient is larger in winter, compared to in the summer. This is arguably a reflection of the stronger effect of large-scale processes on rainfall in winter compared to summer. Interestingly, the parameters of the zero- and non zero-mean processes are found to be quite similar, reflecting the symmetric nature of the truncated processes in the midlatitude and extratropics. It is suggested, in particular, that the process mean can be used as a measure to quantify dryness or wetness of a given region. Ways of model improvement, including power transformation, based on the square root, to represent extremes using exploratory quantile-quantile plots better are also discussed. Copyright (c) 2012 Royal Meteorological Society
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| 3. |
- Riehm, Mats, et al.
(författare)
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Optimization of winter road maintenance energy costs in Sweden : a critique of site specific frost warning techniques
- 2012
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Ingår i: Meteorological Applications. - : Wiley. - 1350-4827 .- 1469-8080. ; 19:4, s. 443-453
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Tidskriftsartikel (refereegranskat)abstract
- Frost formation on roads may cause slippery conditions and thereby increase the risk of accident occurrence. Roads are often treated with preventive operations using de-icing agents (e.g. road salt), which are ideally planned and performed prior to frost formation. The decisions on when and where to treat different road stretches with salt are based on meteorological measurements and forecasts. This paper investigates how uncertainties in meteorological measurements for frost prediction at road weather stations affect the efficiency of winter road maintenance. Different types of uncertainties and errors are discussed, together with potential solutions. The effects on winter road maintenance efficiency are discussed in terms of energy and cost. It was found that improvements in frost warning accuracy and reliability can lead to considerable savings and more efficient winter road maintenance.
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| 4. |
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| 5. |
- Yang, Zhenlin, et al.
(författare)
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How can meteorological observations and microclimate simulations improve understanding of 1913-2010 climate change around Abisko, Swedish Lapland?
- 2012
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Ingår i: Meteorological Applications. - : Wiley. - 1350-4827. ; 19:4, s. 454-463
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Tidskriftsartikel (refereegranskat)abstract
- A detailed analysis of 2 years' hourly microclimatic (mainly surface air temperature) data recently acquired from locations widely dispersed over 700 km2 in the Abisko catchment encompassing Lake Tornetrask in Swedish Lapland is presented in this study. This project is designed to explore the effects of microclimatic variability, past and future climate change (1913-2100) on regional vegetation and land-use changes, at an unique Arctic ecological and climate monitoring site, to aid adaptation of stakeholders to future climate change. Dominant altitudinal lapse rate and radiation effects during summer are revealed in detailed analysis of spatial variations in temperature between the different sites, which become largely negated during winter when cold-air ponding is much more significant. Moreover, near-shore temperatures are moderated significantly by Lake Tornetrask during the spring lake-ice melt season. The extent to which synoptic meteorological conditions affect these factors is explored. Examples of gridded temperature maps for the Abisko region are also presented, produced using a downscaling model based on the temperature data, which have numerous ecological and other applications. The long-term Abisko Scientific Research Station meteorological record, which spans almost a century from 1913 to present is also explored, for evidence of climate change, to set the temperature logger data in a long-term climate context. Exploratory analysis of the possible influence of future regional climate change on ecological/vegetation zones is also briefly discussed. Copyright (C) 2011 Royal Meteorological Society
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