Browsing by Author "Piekarczyk, Jan"

Now showing 1 - 4 of 4
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    Evaluation of Methods for Estimating Lake Surface Water Temperature Using Landsat 8
    (2022-08-08) Dyba, Krzysztof; Ermida, Sofia; Ptak, Mariusz; Piekarczyk, Jan; Sojka, Mariusz
    Changes in lake water temperature, observed with the greatest intensity during the last two decades, may significantly affect the functioning of these unique ecosystems. Currently, in situ studies in Poland are conducted only for 38 lakes using the single-point method. The aim of this study was to develop a method for remote sensing monitoring of lake water temperature in a spatio-temporal context based on Landsat 8 imagery. For this purpose, using data obtained for 28 lakes from the period 2013–2020, linear regression (LM) and random forest (RF) models were developed to estimate surface water temperature. In addition, analysis of Landsat Level-2 Surface Temperature Science Product (LST-L2) data provided by United States Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA) was performed. The remaining 10 lakes not previously used in the model development stage were used to validate model performance. The results showed that the most accurate estimation is possible using the RF method for which RMSE = 1.83 °C and R^2 = 0.89, while RMSE = 3.68 °C and R^2 = 0.8 for the LST-L2 method. We found that LST-L2 contains a systematic error in the coastal zone, which can be corrected and eventually improve the quality of estimation. The satellite-based method makes it possible to determine water temperature for all lakes in Poland at different times and to understand the influence of climatic factors affecting temperature at the regional scale. On the other hand, spatial presentation of thermics within individual lakes enables understanding the influence of local factors and morphometric conditions.
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    Reflectance spectroscopy and machine learning as a tool for the categorization of twin species based on the example of the Diachrysia genus
    (2022-02-17) Dyba, Krzysztof; Wąsala, Roman; Piekarczyk, Jan; Gabała, Elżbieta; Gawlak, Magdalena; Jasiewicz, Jarosław; Ratajkiewicz, Henryk
    In our work we used noninvasive point reflectance spectroscopy in the range from 400 to 2100 nm coupled with machine learning to study scales on the brown and golden iridescent areas on the dorsal side of the forewing of Diachrysia chrysitis and D. stenochrysis. We used our approach to distinguish between these species of moths. The basis for the study was a statistically significant collection of 95 specimens identified based on morphological feature and gathered during 23 years in Poland. The numerical part of an experiment included two independent discriminant analyses: stochastic and deterministic. The more sensitive stochastic approach achieved average compliance with the species identification made by entomologists at the level of 99–100%. It demonstrated high stability against the different configurations of training and validation sets, hence strong predictors of Diachrysia siblings distinctiveness. Both methods resulted in the same small set of relevant features, where minimal fully discriminating subsets of wavelengths were three for glass scales on the golden area and four for the brown. The differences between species in scales primarily concern their major components and ultrastructure. In melanin-absent glass scales, this is mainly chitin configuration, while in melanin-present brown scales, melanin reveals as an additional factor.
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    Winter oilseed-rape yield estimates from hyperspectral radiometer measurements
    (Wydział Nauk Geograficznych i Geologicznych Uniwersytetu im. Adama Mickiewicza, 2011) Piekarczyk, Jan; Sulewska, Hanna; Szymańska, Grażyna
    Spectral reflectance data can be used for estimation of plant biophysical parameters such as seed yield, related to the use of solar energy. A field experiment was conducted to investigate relationships between canopy reflectance and seed yield of winter oilseed rape sown on four different dates. Ground hyperspectral reflectance measurements were made using a hand-held radiometer and multispectral images were taken with a VIS-NIR camera. The different sowing dates generated a wide range of difference in crop spectral response and seed yields. The strongest relationships (R2=0.87) between the yield and spectral data recorded by both sensors occurred at early flowering stages. Later, the presence of flowers caused a decline in the relationship between yield and spectral data especially in the visible (VIS) range. In the full flowering stage the strongest correlation (R2=0.72) with the yield showed vegetation indices of the near-infrared (NIR) bands.
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    Zróznicowanie populacji głazów eolizowanych w różnowiekowych strefach peryglacjalnych Polski Zachodniej
    (Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2010) Antczak-Górka, Barbara; Nowaczyk, Bolesław; Bednorz, Ewa; Medyńska-Gulij, Beata; Milecka, Krystyna; Fortuniak, Krzysztof; Chlachula, Jiri; Wrzesiński, Dariusz; Bródka, Sylwia; Mazurek, Małgorzata; Makohonienko, Mirosław; Rachlewicz, Grzegorz; Słowik, Marcin; Piekarczyk, Jan; Borówka, Krzysztof
    The article presents the results of statistical analysis performed on various populations of wind-polished boulders in the lowland part of Western Poland. The populations were studied in three zones connected with stages of retreat of the Last Glaciation, both in the foreland and hinterland of each of the zones, to accommodate differences in climatic conditions and genetic types of substratum. Those factors influenced the original population of stones that could then be transformed by the wind. It was found that wind-polished boulders were a common occurrence in the study area, whether lying on the surface or as stone horizons underlying aeolian cover sands. Spatial differences among those populations are due to variations of climatic conditions accompanying the successive stages of retreat of the last inland ice.