Lenka Hájková

Dr. Lenka Hájková

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Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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30 July 2022 in Aerobiologia
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Journal Article
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JBJeroen Buters
Jeroen Buters
BCBernard Clot
Bernard Clot
Carmen GalanCarmen Galan
Carmen Galan
RGRegula Gehrig
Regula Gehrig
SGStefan Gilge
Stefan Gilge
BSBarbara Stjepanovic
Barbara Stjepanovic
Pollen monitoring has traditionally been carried out using manual methods first developed in the early 1950s. Although this technique has been recently standardised, it suffers from several drawbacks, notably data usually only being available with a delay of 3–9 days and usually delivered at a daily resolution. Several automatic instruments have come on to the market over the past few years, with more new devices also under development. This paper provides a comprehensive overview of all available and developing automatic instruments, how they measure, how they identify airborne pollen, what impacts measurement quality, as well as what potential there is for further advancement in the field of bioaerosol monitoring.

7 September 2022 in Aerobiologia
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Journal Article
Open access
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FTFiona Tummon
Fiona Tummon
Nicolas BruffaertsNicolas Bruffaerts
Nicolas Bruffaerts
CSCelenk Sevcan
Celenk Sevcan
MCMarie Choël
Marie Choël
BCBernard Clot
Bernard Clot
KVKonstantina Vasilatou
Konstantina Vasilatou
Standards for manual pollen and fungal spore monitoring have been established based on several decades of experience, tests, and research. New technological and methodological advancements have led to the development of a range of different automatic instruments for which no standard yet exist. This paper aims to provide an overview of aspects that need to be considered for automatic pollen and fungal spore monitoring, including a set of guidelines and recommendations. It covers issues relevant to developing an automatic monitoring network, from the instrument design and calibration through algorithm development to site selection criteria. Despite no official standard yet existing, it is essential that all aspects of the measurement chain are carried out in a manner that is as standardised as possible to ensure high-quality data and information can be provided to end-users.

3 October 2024 in Scientific Data
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Mikhail SofievMikhail Sofiev
Mikhail Sofiev
JPJulia Palamarchuk
Julia Palamarchuk
RKRostislav Kouznetsov
Rostislav Kouznetsov
TATamuna Abramidze
Tamuna Abramidze
BABeverley Adams-Groom
Beverley Adams-Groom
AKAri Karppinen
Ari Karppinen
The dataset presents a 43 year-long reanalysis of pollen seasons for three major allergenic genera of trees in Europe: alder (Alnus), birch (Betula), and olive (Olea). Driven by the meteorological reanalysis ERA5, the atmospheric composition model SILAM predicted the flowering period and calculated the Europe-wide dispersion pattern of pollen for the years 1980–2022. The model applied an extended 4-dimensional variational data assimilation of in-situ observations of aerobiological networks in 34 European countries to reproduce the inter-annual variability and trends of pollen production and distribution. The control variable of the assimilation procedure was the total pollen release during each flowering season, implemented as an annual correction factor to the mean pollen production. The dataset was designed as an input to studies on climate-induced and anthropogenically driven changes in the European vegetation, biodiversity monitoring, bioaerosol modelling and assessment, as well as, in combination with intra-seasonal observations, for health-related applications.

1 March 2024 in Aerobiologia
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Journal Article
Open access
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FTFiona Tummon
Fiona Tummon
BABeverley Adams-Groom
Beverley Adams-Groom
CACélia M. Antunes
Célia M. Antunes
Nicolas BruffaertsNicolas Bruffaerts
Nicolas Bruffaerts
JBJeroen Buters
Jeroen Buters
LWLetty A. De Weger
Letty A. De Weger
The advent of automatic pollen and fungal spore monitoring over the past few years has brought about a paradigm change. The provision of real-time information at high temporal resolution opens the door to a wide range of improvements in terms of the products and services made available to a widening range of end-users and stakeholders. As technology and methods mature, it is essential to properly quantify the impact automatic monitoring has on the different end-user domains to better understand the real long-term benefits to society. In this paper, we focus the main domains where such impacts are expected, using Europe as a basis to provide qualitative estimates and to describe research needs to better quantify impacts in future. This will, in part, also serve to justify further investment and help to expand monitoring networks.

20 October 2023 in Climate
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Journal Article
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MMMartin Mozny
Martin Mozny
LHLenka Hájková
Lenka Hájková
VVVojtech Vlach
Vojtech Vlach
VOVeronika Ouskova
Veronika Ouskova
AMAdela Musilova
Adela Musilova
Changes in climatic conditions increase risks associated with crop production in certain regions. Early detection of these changes enables the implementation of suitable adaptation measures in the local area, thereby stabilising agricultural production. Our analysis shows a significant shift in climatic conditions in Czechia between 1961 and 2020. We examined the changes in observed temperature conditions, precipitation distribution, drought occurrences, and frost incidents at a high resolution (0.5 × 0.5 km). The outputs show a significant increase in air temperatures and drought occurrence. Temperature totals above 5 °C in 1991–2020 were 15% higher than in 1961–1990. Furthermore, the relative change in totals above 10 °C was 26% after 1991. Over the last 30 years, drought incidence was four times more frequent than in 1961–1990, particularly in spring. In contrast, no significant changes in the distribution of precipitation occurred, and there was a slight decrease in the probability of frost during the growing season. Ongoing climate change brings warmer and drier conditions to higher-altitude regions in Czechia. Assessing climatic conditions on a global scale is less precise for relatively small and topographically diverse countries like Czechia due to coarse resolution. Therefore, a high-resolution analysis is more appropriate for these countries.

8 November 2022 in Atmosphere
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Journal Article
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PDPetra Dížková
Petra Dížková
LBLenka Bartosova
Lenka Bartosova
MBMonika Bláhová
Monika Bláhová
JBJan Balek
Jan Balek
LHLenka Hájková
Lenka Hájková
Miroslav TrnkaMiroslav Trnka
Miroslav Trnka
The phenological phases of field crops have shifted to earlier times in the Czech Republic in recent decades; additionally, they have shown correlations with temperatures from previous spring months. Using a thermal time model called PhenoClim, the correlations between temperatures and phenophases allow us to evaluate the strongest predictors (i.e., maximum temperature) and indicators of base temperatures and growing degree days for the selected phenophases of winter wheat (Triticum aestivum L.). With the help of this model, it is possible to explain 0.6–0.82% of the phase variability and to estimate the onset of phenophases for the selected time period and stations (with the RMSE values of 9.4 days for jointing, 4.3 days for heading, and 5.3 days for full ripeness). To further refine the modeled onsets of phenophases, we used satellite data, specifically the normalized difference vegetation index and the enhanced vegetation index 2 from MODIS; based on these vegetation indices, the start of the growing season (SOS) was determined. After including SOS to model PhenoClim, we modeled the onsets of phenophases, with average accuracies ranging from 6.2 to 15.2. By combining the thermal time model and remote sensing data, specifically the data concerning the determination of SOS, we can refine the modeling of the onset of full ripeness in some locations.