New Caledonia experiences a decrease in surface solar irradiation since 2004, of order of 4% of the mean yearly irradiation, and amounts to 9 W m 2. The preeminent roles of the changes in cloud cover and to a lesser extent, those in aerosol optical depth on the decrease in yearly irradiation are evidenced. The study highlights the role of data sets offering a worldwide coverage in understanding changes in solar radiation and planning large solar energy plants.
We propose an innovative method to estimate the Photosynthetically Active Radiation (PAR) under clear sky conditions derived from the fast approach of Kato et al. (1999). It provides very good results better than the two state-of-the-art empirical methods computing the daily mean of PAR from the daily mean of total irradiance. In addition, this technique may be extended to be able to accurately estimate other spectral quantities taking into account absorption of plants photosynthetic pigments.
Wind spatial heterogeneity in a coastal area (Alfacs Bay, northwestern Mediterranean Sea) is described using a set of observations and modelling results. Observations during 2012–2013 reveal that both N–NW winds and sea breezes appear to be affected by the local orography promoting high wind variability in relatively short spatial scales. The importance of wind models’ spatial resolution is also assessed and used to describe the spatial variability of the typical winds in the region.
We assessed the quality of the seasonal precipitation forecasts issued by Regional Climate Outlook Forum for Malawi and Zambia. The forecasts, issued in August, are of rainy season rainfall accumulations for early and late season. The forecasts are rather well-calibrated, but cannot discriminate between different events. But these results can be too pessimistic, because forecasts have gone through much development lately, and forecasts using current methodology might have performed better.
Ensemble prediction systems are becoming of more and more interest for various applications. They are used to account for uncertainties that exist from the very beginning of a forecast due to the chaotic behavior of atmospheric processes as well as approximations in numerical models. Ensemble nowcasting systems are therefore increasingly requested by end users. In this study we show that En-INCA, an integrated probabilistic nowcasting system, is able to improve existing state-of-the-art LAM-EPS.
Germany’s national meteorological service (Deutscher Wetterdienst, DWD) houses in Offenbach and Hamburg huge archives of historical handwritten journals of weather observations. They comprise not only observations from Germany, but also of the oceans and land stations in many parts of the world. DWD works on the digitisation and quality control of these archives. The paper presents the current status.
Many users of climate information are unaware of the availability of reanalysis feedback data and input observations, and uptake of feedback data is rather low. The most important factors limiting the use of this data is that the users feel that there is no easy interface to get the data or they do not find it at all. The relevant communities should invest resources to develop tools and provide training to bridge the gap between current capabilities and comprehensive exploitation of the data.
The paper discusses the derivation of precipitation climate maps over Belgium from daily observations available for the period 1981-2010. Several mapping approaches are compared in a cross-validation exercise. A large panel of climate maps are derived. In particular, the main spatio-temporal features of the annual cycle of rainfall in Belgium are extracted by principal component analysis (PCA).
First measurements at the Atmospheric Station Křešín u Pacova revealed a seasonal variability of elemental and organic carbon with slightly higher autumn and winter concentrations. A suitable statistical method for the replacement of very low elemental carbon concentrations (i.e. under the instrument quantification limit) was found. In summer, the top of the 250 m tall station tower is frequently above the nocturnal surface inversions, thus being decoupled from local influences.
Emergency rescue data and weather reanalysis data were combined to study the spatial and decadal characteristics of potential forest damage days in Finland due to windstorms. The most prone area for damage days was the south-western part of Finland. Results also indicated a lull period during the 1990s compared to the 1980s and 2000s, albeit no trend was evident. The study highlighted the importance of not only focusing on wind speeds, but also soil conditions.
In the framework of the interdisciplinary FORBIO Climate research project, this paper explains how the gridded daily temperature (minimum and maximum) data set was generated from a consistent station network between 1980 and 2013 in Belgium. Data quality control procedures were applied to the station records to ensure that only valid measurements will be involved in the gridding process. The performance of different interpolation methods has been assessed.
The aim of this research is to compare the results of two modern multiple break point homogenization methods, namely ACMANT and HOMER, over a Pyrenees temperature dataset in order to detect differences between their outputs which can affect future studies. Both methods are applied to a dataset of 44 monthly maximum and minimum temperature series placed around central Pyrenees and covering the 1910–2013 period.
Due to the evolution of the observation network, hourly 2m temperature analysis performed by reanalysis systems shows temporal inhomogeneities. In this study, the diurnal temperature cycle has been reconstructed for stations which only record extreme temperatures to produce new “pseudo” hourly temperature observations. Then they are provided to analysis systems; the results have shown that it enables reducing the bias in temperature analysis.
A solar radiation measurement campaign was performed in the south-eastern village of Marsaxlokk (35º 50' N; 14º 33' E; 10 m a.s.l.), Malta, between 15 May and 15 October 2012. Erythemal solar radiation (UVER), horizontal global and diffuse components were recorded. Aerosols effects on solar irradiances are evaluated using the Aerosol Modification factor (AMF). Results indicate a greater aerosol effect on UVER than on global solar irradiance. Several dust event trajectories are identified.
Long term meteorological records from stations associated with villages are generally classified as rural and assumed to have no urban influence. Using temperature sensor networks installed around two such stations, spatial variations of the same order magnitude as the long-term temperature trend from these stations were found. The potential bias in the long term series therefore warrants careful consideration in temperature trend evaluation also in village stations.
Adverse meteorological conditions are one of the major causes of accidents in aviation, resulting in substantial human and economic losses. For this reason it is crucial to monitor and early forecast high impact weather events. In this context, CIRA (Italian Aerospace Research Center) has implemented MATISSE (Meteorological AviaTIon Supporting SystEm), an ArcGIS Desktop Plug-in able to detect and forecast meteorological aviation hazards over European airports, using different data sources.
F. Kaspar, J. Helmschrot, A. Mhanda, M. Butale, W. de Clercq, J. K. Kanyanga, F. O. S. Neto, S. Kruger, M. Castro Matsheka, G. Muche, T. Hillmann, K. Josenhans, R. Posada, J. Riede, M. Seely, C. Ribeiro, P. Kenabatho, R. Vogt, and N. Jürgens
One task of the “Southern African Science Service Centre for Climate Change and Adaptive Land Management” (www.sasscal.org) is the provision of climate data for Southern Africa. Extension and improvements of observational networks in Angola, Botswana, Namibia, Zambia and South Africa are supported. This effort is complemented by an improvement of climate data management at national weather authorities, capacity building activities and an extension of the data bases with historical climate data.
This paper investigates meteorological droughts in Europe for the periods 1981-2010, 2041-2070 and 2071-2100 under a moderate emissions scenario. SPI and SPEI are used to analyze drought frequency, duration, severity, and intensity. Results show that southern Europe is likely to be hit by longer, more frequent, severe, and intense droughts in the near future (2041-2070) and even more in the far future (2071-2100), while less severe and fewer drought events are likely to occur in northern Europe.
Wind speed measured at the German stations correlate well with reanalysis fields. Monthly means from two global reanalyses (ERA-20C, ERA-Interim) and one regional reanalysis (COSMO-REA6) were analysed and correlate well for the majority of the German stations. Thus we conclude that the monthly and seasonal anomalies recorded at these stations can be understood as representative for a spatial area comparable to the resolution of the reanalyses, at least for the recent years.
The VIADUC project is to evaluate existing French climate services, as well as to imagine future development in support of adaptation. Climate scientists work together with end-users and a service designer. The designer's role is to propose an innovative approach based on the interaction between scientists and citizens. The users' needs for climate information have been assessed. The lessons learned led to actions which are presented in this paper.
Within the European Union’s seventh Framework Programme project Uncertainties in Ensembles of Regional Re-Analyses (UERRA), ensembles of RRAs covering the European area are produced and their uncertainties are quantified. In this study, we discuss different methods for quantifying the uncertainty of RRAs in order to answer the question to which extent the smaller scale information (or resulting statistics) provided by the RRAs can be relied on.