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1

Complementing ERA5 and E-OBS with high-resolution river discharge over Europe

Hagemann Stefan, Stacke Tobias

Oceanologia

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2023

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Vol. 65 (1)

230--248

EN

The 0.5° resolution of many global observational or quasi-observational datasets is not sufficient for the evaluation of current state-of-the-art regional climate models or the forcing of ocean model simulations over Europe. While higher resolved products are available for meteorological data, e.g. ERA5 reanalysis and the E-OBS vs 22 (EOBS22) datasets, they lack crucial information at the land-ocean boundary. ERA5 is frequently used to force regional climate models (RCMs) or ocean models and both datasets are commonly used as reference datasets for the evaluation of RCMs. Therefore, we extended both datasets with high-resolution river discharge for the period 1979–2018. On the one hand, our discharge data close the water cycle at the land-ocean interface so that the discharges can be used as lateral freshwater input for ocean models applied in the European region. On the other hand, the data can be used to identify trends in discharge that are induced by recent climate change as ERA5 and EOBS22 are rather independent datasets. The experimental setup to generate the discharges was chosen in a way that it could be easily adapted in a climate or Earth system modelling framework. Consequently, the recently developed 5 Min. horizontal resolution version of the hydrological discharge (HD) model was used to simulate discharge. It has already been applied in multiple climate modelling studies and is coupled within several global and regional Earth system models. As the HD model currently does not regard direct human impacts of the river runoff, it is well suited to investigate climate change-related discharge trends. In order to calculate the necessary gridded input fields for the HD model from ERA5 and EOBS22 data, we used the HydroPy global hydrological model. For both experiments, we found that the general behavior of discharge is captured well for many European rivers, which is consistent to earlier results. For the EOBS22 based discharges, a widespread low bias in simulated discharge occurs, which is likely caused by the missing undercatch correction in the underlying precipitation data. The analysis of trends over Southeastern Europe was hampered by missing data in EOBS22 after 2004. Using both experiments, we identified consistent trend patterns in various discharge statistics, with increases in low flow characteristics over Northern Europe and general drying trends over Central and Southern Europe. In summary, we introduced an experimental setup that is useful to generate high-resolution river runoff data consistent with the meteorological forcing for historical periods and future scenarios from any climate model data instead of having to rely on observed time series.

2

Typowe lata meteorologiczne TLM2000 – analiza danych źródłowych oraz wpływ na praktykę doboru urządzeń i optymalizację pracy systemów HVACR

Narowski Piotr

Chłodnictwo i Klimatyzacja

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2023

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nr 7

28--37

PL

Nowe typowe lata meteorologiczne TLM2000 to projekt mający na celu wyznaczenie dla obszaru Polski zaktualizowanych danych pogodowych stanowiących podstawę do projektowania i doborów urządzeń. Parametry te obliczone zostały na podstawie dostępnych danych meteorologicznych stacji synoptycznych Instytutu Meteorologii i Gospodarki Wodnej IMGW oraz modeli powtórnej analizy wstecznej bazy danych ERA5 systemu Copernicus obejmujących lata 2001÷2020. Wprowadzenie nowych danych projektowych pozwala urealnić analizy energetyczne oraz zoptymalizować pracę systemów HVACR poprzez bardziej dostosowany dobór wielkości urządzeń i systemów HVACR do warunków temperaturowych obecnie panujących w Polsce.

3

The impact of initial and boundary conditions on severe weather event simulations using a high-resolution WRF model. Case study of the derecho event in Poland on 11 August 2017

Figurski Mariusz J., Nykiel Grzegorz, Jaczewski Adam, Bałdysz Zofia, Wdowikowski Marcin

Meteorology Hydrology and Water Management. Research and Operational Applications

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2022

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Vol. 10, Iss. 2

60--87

EN

Precise simulations of severe weather events are a challenge in the era of changing climate. By performing simulations correctly and accurately, these phenomena can be studied and better understood. In this paper, we have verified how different initial and boundary conditions affect the quality of simulations performed using the Weather Research and Forecasting Model (WRF). For our analysis, we chose a derecho event that occurred in Poland on 11 August 2017, the most intense and devastating event in recent years. High-resolution simulations were conducted with initialization at 00 and 12 UTC (11 August 2017) using initial and boundary conditions derived from the four global models: Global Forecast System (GFS) from the National Centers for Environmental Prediction (NCEP), Integrated Forecast System (IFS) developed by the European Center for Medium-Range Weather Forecasts (ECMWF), Global Data Assimilation System (GDAS) and ERA5. For the last, we made separate calculations using data at the pressure and model levels. The results were evaluated against surface and radar data. We found that the simulations that used data from the GDAS and GFS models at 12 UTC were the more accurate, while ERA5 gave the worst predictions. However, all models were characterized by a low probability of detection and a high number of false alarms for simulations of extreme precipitation and wind gusts.

4

TLM2000 – Typowe lata meteorologiczne dla Polski wyznaczone na podstawie danych meteorologicznych i klimatycznych z lat 2001-2020

Narowski Piotr

Ciepłownictwo, Ogrzewnictwo, Wentylacja

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2022

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T. 53, nr 9

7--20

PL

W artykule przedstawiono wyniki prac związanych z wyznaczeniem nowych typowych lat meteorologicznych dla Polski obliczonych na podstawie dostępnych danych meteorologicznych stacji synoptycznych Instytutu Meteorologii i Gospodarki Wodnej IMGiW oraz modeli powtórnej analizy wstecznej bazy danych ERA5 systemu Copernicus obejmujących lata 2001-2020. Typowe lata meteorologiczne dotychczas używane w Polsce do analiz energetycznych budynków zostały opracowane w 2004 r. na podstawie danych meteorologicznych IMGiW obejmujących lata 1971-2000. Dane źródłowe wykorzystane wówczas do wyznaczenia typowych lat meteorologicznych dla Polski, zawierały kilka podstawowych 3-godzinnych parametrów meteorologicznych oraz modelowane wartości natężenia promieniowania słonecznego pochodzące z nieopisanego modelu matematycznego. Przebiegi wartości w typowych lat meteorologicznych opracowanych w 2004 r. wielokrotnie poddawane były krytyce, a w szczególności dotyczyło to wartości natężenia premiowania słonecznego. Mając na uwadze powyższe krytyczne analizy oraz uwzględniając obserwowalne zmiany klimatyczne należy uznać, że typowe lata meteorologicznych dla Polski wyznaczone 18 lat temu stały się nieaktualne. Artykuł opisuje źródła danych i metodę wyznaczenia nowych typowych lat meteorologicznych dla Polski – TLM2000, które mają szczególne znaczenie w symulacjach energetycznych budynków stosowanych w metodyce świadectw charakterystyki energetycznej oraz projektowaniu zapotrzebowania na energię budynków niskoenergetycznych wyposażonych w nowoczesne instalacje prosumenckie.

EN

The article presents the results of works related to the determination of new typical meteorological years for Poland, calculated on the basis of the available meteorological data of the synoptic stations of the Institute of Meteorology and Water Management and reanalysis of the ERA5 database of the Copernicus system covering the years 2001-2020. Typical meteorological years currently used in Poland for energy analyzes of buildings were developed in 2004 on the basis of meteorological data from the Institute of Meteorology and Water Management for the years 1971-2000. Source data used at that time to determine typical meteorological years for Poland included several basic 3-hour meteorological parameters and modeled values of solar radiation intensity derived from an undescribed mathematical model. The courses of values in typical meteorological years developed in 2004 were subject to many criticisms, in particular the value of the intensity of solar radiation. Bearing in mind the above critical analyzes and taking into account the observable climate changes, it should be concluded that the typical meteorological years for Poland, designated 18 years ago, have become obsolete. The article describes the data sources and the method of determining new typical meteorological years for Poland ‒ TLM2000, which are of particular importance in energy simulations of buildings used in the methodology of energy performance certificates and in designing energy demand of low-energy buildings equipped with modern prosumer installations.

5

Value addition in coupled model intercomparison project phase 6 over phase 5: global perspectives of precipitation, temperature and soil moisture fields

Dutta Riya, Maity Rajib

Acta Geophysica

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2022

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Vol. 70, no 3

1401--1415

EN

This study establishes the improvements in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) simulations as compared to its previous version, CMIP5. First, the historical simulations are compared with the reanalysis products from the 5th generation European Centre for Medium-Range Weather Forecasts (ERA5). Quality improvement in CMIP6 is assured through its correspondence with ERA5 in terms of mean, standard deviation and mean bias. Global fields of three hydrometeorological variables, i.e. temperature, precipitation and soil moisture, are considered from multiple General Circulation Models. Among the three variables, maximum improvement is noticed in case of soil moisture followed by precipitation, especially in the tropical belt. In case of temperature, the mean bias has reduced by±3 °C across the parts of North America, Africa, and South Asia. Better reliance on the CMIP6 motivates for a trend analysis to peek into the future. The results indicate a significant increasing trend for precipitation in the temperate, polar and sub-polar regions, whereas a significant increase in temperature is noticed almost all across the world with highest slope in the polar and sub-polar regions. Furthermore, soil moisture shows a significant trend that can be grouped continent-wise, e.g. Africa, Central and South Asia exhibit an increasing trend, whereas North and Central America and Northern parts of South America exhibit an overall decreasing trend. Apart from underlining the better reliance on CMIP6, the findings of this study will also be useful across different parts of the world for many climate related studies using CMIP6.

6

Spatial and temporal evaluation of global rainfall products in a data-scarce region: The Dez Basin, Iran

Khoshchehreh Mostafa, Ghomeshi Mehdi, Shahbazi Ali, Bolboli Hossein, Saberi Hamed, Gorjizade Ali

Journal of Water and Land Development

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2021

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no. 48

148--161

EN

The limitation in approachability to rainfall data sources with an appropriate spatial-temporal distribution is a significant challenge in different parts of the world. The development of general circulation models and mathematical algorithms has led to the generation of various rainfall products as new sources with the potential to overcome the shortage in datascarce basins. In this study, the performance of the PERSIANN-CCS and CMORPH satellite-based rainfall product, as well as the ERA5 and ERA-Interim reanalysis, was evaluated based on detection skill and quantitative metrics in a daily, monthly and seasonal time scales in the Dez basin located in the southwest of Iran. The basin has a wide topographic variation and scattered rain gauge stations. Overall results denote that the ERA5 dataset has the best performance in all statistic verification than other rainfall products. Based on the daily evaluation of all rainfall products, the false alarm rate (FAR) is higher than 0.5, so none of the datasets could capture the temporal variability of rainfall occurrence. This study has covered the western parts of the Zagros steep slopes in which the topographic conditions have a significant effect on the activity of rainfall systems. On a monthly scale, the mean value of the correlation coefficient (CC) for ERA5, ERA-Interim, PER-SIANN-CCS, and CMORPH was equal to 0.86, 0.85, 0.51, 0.39, respectively. The results of seasonal evaluation suggested that all datasets have better rainfall estimation in autumn and winter, and the capability of all datasets dramatically decreased in the spring. The current paper argues that the ERA5 reanalysis typically outperforms ERA-Interim and can be considered as a reliable rainfall source in the future hydrological investigation in the southwest of Iran.