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1

Selected microstructural phenomena in FSW joints

Wciślik Wiktor

Structure and Environment

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2024

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Vol. 16, no. 2

97--110

EN

The article is a literature review on selected phenomena leading to microstructural changes in material welded using the friction stir welding (FSW) method. Particular attention was paid to the phenomena of grains recrystallization, as well as dissolution and reprecipitation of second phase particles, resulting from temperature changes during FSW. Temperature transformations in different zones of the FSW joints were characterized. The role of base material phase transformation in the formation of new particles is discussed. In the tested aluminum alloys and stainless steels, this process was particularly intensified in the heat affected zone (HAZ). In areas subjected to high temperature and significant plastic deformation (nugget zone and thermomechanically affected zone), this phenomenon did not occur or was characterized by small intensity. It was indicated that the phenomenon of particle formation clearly affects the strength parameters of the joint.

PL

W artykule przedstawiono przegląd literatury dotyczący wybranych zjawisk prowadzących do zmian mikrostrukturalnych w metalach spawanych metodą zgrzewania tarciowego (FSW). Szczególną uwagę zwrócono na zjawiska rekrystalizacji ziaren oraz rozpuszczania i ponownego wytrącania cząstek drugiej fazy, zachodzące jako efekt zmian temperatury podczas FSW. Scharakteryzowano zmiany temperatury w różnych strefach złączy FSW. Omówiono rolę przemian fazowych materiału podstawowego w powstawaniu nowych cząstek. W badanych stopach aluminium i stalach nierdzewnych proces ten był szczególnie nasilony w strefie wpływu ciepła (SWC). W obszarach narażonych na działanie wysokiej temperatury i znacznych odkształceń plastycznych (jądro zgrzeiny i strefa uplastycznienia termomechanicznego) zjawisko to nie występowało lub charakteryzowało się niewielkim natężeniem. Wykazano, że zjawisko tworzenia cząstek wyraźnie wpływa na parametry wytrzymałościowe złącza.

2

Burza superkomórkowa z deszczem nawalnym 8 września 2022 roku w rejonie Gorzowa Wielkopolskiego

Soroka Jakub, Matczak Patryk

Przegląd Geofizyczny

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2024

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Z. 1-2

25--46

PL

W artykule opisano przypadek deszczu nawalnego związanego z długotrwałą, quasi-stacjonarną superkomórką burzową, która wystąpiła nad ranem 8 września 2022 r. w rejonie Gorzowa Wielkopolskiego. Warunki atmosferyczne charakteryzowały się wówczas sporą niestabilnością atmosfery oraz dużą zawartością wilgoci w powietrzu, a także niewielkim przepływem powietrza. Istotne dane minutowe ukazały rzadki przypadek związany z gwałtownymi napływami cieplejszego powietrza podczas trwania burzy o symptomach zbliżonych do tzw. zjawiska heat burst. Przy opadzie trwającym niespełna 3,5 godz. sumy opadów osiągnęły od 144,9 mm w Gorzowie (stacja IMGW-PIB) do 218 mm w Wawrowie (dane nieoficjalne). Najwyższa dobowa suma opadów oszacowana przy pomocy reanalizy RainGRS Clim wystąpiła w rejonie Czechowa i wyniosła 237 mm. Zarejestrowane sumy i natężenie opadów były jednymi z największych w historii pomiarów jakie odnotowano na obszarze Polski nizinnej. Rozwój superkomórki burzowej przypadł na wczesne godziny poranne, czyli poza okresem typowego występowania burz w przebiegu dobowym. Na intensyfikację rozwoju burzy wpływ mogło mieć wzmocnienie orograficzne w obrębie krawędzi między wysoczyzną i doliną rzeki Warty. Wystąpienie deszczu nawalnego spowodowało powódź błyskawiczną i olbrzymie zniszczenia w lokalnej infrastrukturze, zwłaszcza w sołectwach Czechów i Wawrów.

EN

A heavy rainfall episode associated with a long-lived, quasi-stationary supercell thunderstorm occurred in the Gorzów Wielkopolski area (western Poland) on September 8, 2022. The atmospheric environment was saturated with moisture and instability with relatively weak air flow. Precise synoptic 1-minute data showed a very rare event associated with sudden advection of warm air during a thunderstorm, closely resembling the heat burst phenomenon. The highest rainfall amounts were recorded in Gorzów Wielkopolski (144.9 mm) and Wawrów (218 mm, unofficial data). Based on the RainGRS Clim reanalysis, a maximum of daily total precipitation was estimated at 237 mm in Czechów village. It was one of the most extreme precipitation events in the Polish lowlands. The supercell thunderstorm developed unusually in the early morning hours, outside of the period of maximum thunderstorm activity. It is possible that the edge between the Gorzow highlands and the Warta river valley favoured orographically forced convective precipitation. As a consequence of this unprecedented event, flash floods and destruction of local technical infrastructure were observed, particularly in Czechów and Wawrów villages.

3

Recovery of iron phosphate and lithium carbonate from sulfuric acid leaching solutions of spent LiFePO4 batteries by chemical precipitation

Jing Chen, Tran Thanh Tuan, Lee Man Seung

Physicochemical Problems of Mineral Processing

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2024

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Vol. 60, iss. 3

art. no. 189463

EN

The recycling of lithium and iron from spent lithium iron phosphate (LiFePO4) batteries has gained attention due to the explosive growth of the electric vehicle market. To recover both of these metal ions from the sulfuric acid leaching solution of spent LiFePO4 batteries, a process based on precipitation was proposed in this study. Since ferric and ferrous ions coexisted in the leaching solution, all the ferrous ions were first oxidized to ferric ions by adding H2O2 to the leaching solution. About 99% iron(III) was recovered as iron phosphate by adjusting the solution pH to 2 at 25°C for 30 mins. After the precipitation of iron phosphate, the remaining Li(I) in the filtrate was recovered as lithium carbonate by precipitation with Na2CO3 as a precipitant. Addition of acetone to the filtrate at room temperature greatly enhanced the precipitation percentage of Li(I). Moreover, solid Na2CO3 was better than Na2CO3 solution in precipitating Li(I). About 95% of lithium ions was recovered as carbonate precipitates under the optimum conditions: solution pH = 11, 3.0 molar ratio of solid Na2CO3 to Li(I), 7/5(v/v) volume ratio of acetone to the filtrate, 25°C, 300 rpm for 2 hrs.

4

Acceleration of the hydrological cycle and its impact on water availability over land: an adverse effect of climate change

Ehtasham Laraib, Sherani Sadia Hassan, Nawaz Faheem

Meteorology Hydrology and Water Management. Research and Operational Applications

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2024

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Vol. 12, Iss. 1

1--21

EN

The hydrological cycle, or water cycle, is one of the most important geochemical cycles on our planet. Normal functioning of its mechanisms (evaporation/evapotranspiration, condensation, and precipitation) is very important for the well-being of human beings. However, the acceleration of the hydrological cycle, mainly due to global warming, is increasing the frequency and intensity of extreme events (floods, droughts, and alterations in water resources) in many regions around the globe. This acceleration or intensification occurs because of rising temperature, which intensifies and speeds up evaporation (probable increase of 5.2%) and precipitation (probable increase of 6.5%); hence this scenario is escalating climate change. According to the datasets retrieved from the Global Land Data Assimilation System (GLDAS) of NASA, rain precipitation rate has shown changes in various regions of the world. Consequently, extreme and frequent events of heavy precipitation, floods, and droughts are also deteriorating the quality of water and preventing recharge of water reservoirs. Although some regions of the world will experience positive outcomes of this scenario in terms of water availability (due to frequent intense precipitation), most of the world’s regions are expected to face the daunting issue of water unavailability, as predicted by many researchers.

5

The effect of meteorological conditions on the course of development stages and yield of winter wheat in southern Poland

Skowera Barbara, Kulig Bogdan, Ziernicka-Wojtaszek Agnieszka, Grygierzec Wiesław, Ziółkowska Elżbieta, Lepiarczyk Andrzej

Journal of Water and Land Development

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2024

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no. 60

157--166

EN

Yield and the course of crop vegetation are the result of the interaction between the level of cultivation technology and the course of meteorological conditions, which are a variable production factor. The aim of the study was to quantify the effect of meteorological conditions on the course of development stages and yield of winter wheat cultivated in two technological variants (A1 - medium-intensive and A2 - intensive). The paper uses data on yield and timing of winter wheat development stages from four Experimental Stations for Variety Testing (Pol. Centralny Ośrodek Badania Odmian Roślin Uprawnych - COBORU) experimental stations from 2007-2016 located within the Upper Vistula and Upper Oder River basins. To determine the dependence of the length of development stages of winter wheat on the values of selected meteorological elements, the linear regression metod, correlation coefficient. It was found that the lengths of the selected developmental stages are positively correlated with air temperature and negatively correlated with the sum and number of days with precipitation in these stages. A 1°C increase in air temperature resulted in a shortening of the shooting - heading and heading - full maturity periods by 2.5 and 2.8 days respectively. An increase of 100 mm of precipitation in the periods sowing - full maturity and heading - full maturity resulted in an increase of these periods by 5 and 10 days. Increasing the number of days with precipitation by 10 days in the sowing - full maturity and heading - vax maturity stages resulted in extending these stages by 4.1 to 4.4 and 7 to 7.5 days for the A1 and A2 cropping technologies, respectively.

6

Atmospheric precipitation in the West Pomeranian Voivodeship in Poland (1991-2020) : Annual and seasonal variability

Nidzgorska-Lencewicz Jadwiga, Mąkosza Agnieszka, Czarnecka Małgorzata

Journal of Water and Land Development

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2024

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no. 61

202--212

EN

The paper presents a detailed analysis of precipitation conditions in the West Pomeranian Voivodeship in Poland, covering data from 21 poviats1. The basic data consisted of monthly sums of atmospheric precipitation from 49 stations of the Institute of Meteorology and Water Management National Research Institute (Pol.: Instytut Meteorologii i Gospodarki Wodnej Państwowy Instytut Badawczy - IMGW-PIB) in 1991-2020. Variability of precipitation conditions was demonstrated through annual and seasonal totals, the share of seasonal precipitation in annual totals, and the ratios of summer to winter precipitation and autumn and spring precipitation. It was found that area averaged annual totals ranged from below 600 mm in the poviats located in the west of the Voivodeship to more than 800 mm in the poviats located in the north-east. On average, the lowest annual totals were recorded in the area of the Police (550 mm) and Gryfino (565 mm) poviats, and the average highest in the Koszalin (842 mm) poviat. In most poviats, there was a slight, statistically insignificant tendency of increasing annual totals. The contribution of precipitation in spring, summer, autumn, and winter to the annual total in the voivodeship was 21, 33, 24, and 22%, respectively. The greatest year-to-year variability was found for summer (Vs = 28-39%) and winter precipitation totals (Vs = 29-35%). The most statistically significant result of the analysed features was identified for the calendar spring. The most prominent statistically significant changes in precipitation conditions were observed in the Goleniów, Kamień, and Sławno poviats.

7

The Climate Change Impact on the Development of Droughts in Ukraine

Polevoy Anatoly, Barsukova Olena, Husieva Kateryna, Zhygailo Olena, Volvach Oksana, Kyrnasivska Nataliia, Tolmachova Alla, Zhygailo Taras, Danilova Nataliia, Kostiukievych Tetiana

Journal of Ecological Engineering

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2024

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Vol. 25, nr 6

194--205

EN

The paper considers the peculiarities of the climate change influence on the dynamics of drought development in Ukraine. The analysis was performed for average long-term climatic conditions during the growing season (1981–2020) and under climate change scenarios RCP 4.5 and RCP 8.5 for the period of 2021–2050 (for the period as a whole and by the decades: 2021–2030, 2031–2040, 2041–2050). The drought development was studied over relatively short periods of time (ten days) at the main agroclimatic regions of Ukraine (Polissia, Forest-Steppe, Northern and Southern Steppe). The assessment of the aridity of ten-day periods was accomplished by means of a set of aridity indicators by Selyaninov, Shashko, Budagovskiy and Bova, which corrects and supplements each other; this made it possible to consider in detail the genesis of climate-induced drought in the agroclimatic regions of Ukraine. Analysis of the study results showed that the development of drought conditions in all agroclimatic regions is expected as early as in the first decade (2021–2030). According to both scenarios, from 4–6 in Polissia to 16–17 severe and very severe droughts in the Southern Steppe are expected. In the second decade (2031–2040), under RCP4.5, improvement in moistening conditions is expected in Polissia and Forest-Steppe and under RCP8.5, an increase in the level of aridity is expected in these agroclimatic regions. In the Northern Steppe and Southern Steppe the number of moderately, very and extremely dry ten-day periods will increase (from 9 to 17). In the third decade (2041–2050), under the RCP4.5 scenario, very severe aridity conditions are assumed in all agroclimatic regions. Under RCP8.5, good moistening conditions and, according to both criteria, a small number of dry ten-day periods are expected in Polissia and Forest-Steppe. As for the conditions at the Northern and Southern Steppes very severe drought conditions are expected (from 8 to 17 ten-day periods with moderate, severe and very severe drought). For 2021–2050 on the whole, there will be an increase in aridity during the growing season in all agroclimatic regions of Ukraine.

8

Monthly and Annual Precipitation in Arid Environment of the Daoura Watershed (South-Eastern Morocco) – Homogenization and Trend Analysis

Chanyour Yassine, El Achari Ouafaa, Hanchane Mohamed, Obda Khalid, Kessabi Ridouane

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 4

125--142

EN

The high variability of the sub-desert climate, especially in the south-eastern region of Morocco, has severe socio-economic impacts on the inhabitant’s way of life, as is the case in the Daoura watershed, where this variability is associated with droughts or exceptional rainfall. The data collected from the Guir-Ziz-Rheriss hydraulic agency were processed, corrected and analyzed using the Climatol package (version 4.0.0) developed in R software to homogenize rainfall data. Through this work, the significance and amplitudes of annual and monthly rainfall trends were defined using the Mann-Kendall test and Sens’s slope estimator, while comparing the results of raw and homogenized data. The Daoura watershed has a sub-desert climate, and the homogenization process revealed a few rainfall stations with significant positive trends at confidence levels ranging from 90% to 95%. According to the raw and homogenized data, the majority of these stations are located in the High Atlas (CR1) and Anti-Atlasic (CR2) zones, where there is considerable spatiotemporal variability in rainfall from one year to the next. The essential objective of this scientific paper was to analyze the spatiotemporal variability of monthly and annual precipitation and to study their trends through rainfall data homogenized by the climatol package (version 4.0.0) from 13 stations over a period (1957–2018). The contribution of this study to science is the rainfall data it offers, which is useful for managing natural resources in sub-desert areas.

9

Evaluation of the Impact of Gap Filling Technology in Precipitation Series on the Estimation of Climate Trends, the Case of the Souss Massa Watershed

Ismail Oumechtaq, Laghzali Abbdelmajid, Bahaj Tarik, Abderrahim Oulidi, Lamya Amghar, Abdelhamid Allaoui, Manal Mouadil, Boualoul Mustapha, El Mostafa Bachaoui, Khalid Elkhaldi

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 4

241--251

EN

Accurate climatic data, especially precipitation measurements, play a critical role in various studies concerning the water cycle, particularly in modeling flood and drought risks. Unfortunately, these datasets often suffer from temporary gaps that are randomly dispersed over time. This study aims to assess the effectiveness of three imputation methods: KNN, MICE, and missForest, in impute missing values in climate series. The evaluation is conducted in two distinct rainfall regimes: the Moulouya basin and the Sous Massa basin. The performance analysis considers the percentage of missing data across the entire dataset. The imputed datasets are used to estimate annual precipitation, which are then subjected to statistical tests to identify potential trends and detect changepoints. The analysis focuses on the precipitation series within the Souss Massa watershed, encompassing 27 rainfall stations. Results indicate that data imputation has a highly positive impact on the study of rainfall series trends and change point detection. The study found that studying trends without data imputation could lead to questionable conclusions. The most significant breakpoints detected in the analyzed rainfall series were in the years 1988, 1991, 1997, 2007, and 2010. The decrease in precipitation at stations showing a downward trend varies between -60 mm and -137 mm using the MICE method, and between -40 mm and 186 mm using the missForest method.

10

Analysis of Pluviograms Recorded in the Area of a Phosphogypsum Heap at Wislinka, Poland

Korzec Aleksandra

Archives of Hydro-Engineering and Environmental Mechanics

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2024

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Vol. 71, nr 1

43--57

EN

The paper is devoted to the long-term project concerning monitoring and stability analysis of a 40 m high phosphogypsum heap located at Wislinka, Poland. The research presented in the paper focused on collecting and processing rainfall data, which subsequently allows us to perform numerical simulation of rainfall impact on heap’s behaviour. Such analysis requires time history of rainfall intensity, that is recorded by an automatic precipitation station. Since this is not common monitoring equipment, the characteristics of the station installed in the immediate vicinity of the heap are presented, and the data obtained in two experiments conducted in the laboratory are discussed. The analysis revealed that differences between introduced and measured total rain are as large as 10% for very heavy rains. Moreover, the recorded maximum rainfall intensity often includes errors. The data processing procedure to obtain time history of rainfall intensity is presented on the basis of data collected in the first half of the hydrological year 2023 (the first period of the station’s operation). The total precipitation registered was 107 mm, and the maximum daily rain was only 26 mm. However, first single and multi-stage rainfall models for the Wislinka region that would be applied into numerical simulations are presented.

11

Influence of Incidental Water on Changes in the Amount of Wastewater Flowing into the Treatment Plant

Jóźwiakowska Karolina, Kaczor Grzegorz, Marczuk Andrzej, Bugajski Piotr

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 6

392--405

EN

The paper determines the effect of daily precipitation, occurring in the sewerage catchment area located in the Jastków Commune, on the volume of wastewater, flowing into the treatment plant in Snopków. Daily and annual volumes of incidental water, caused by precipitation, flowing into the selected sewerage system were determined, and then the annual costs incurred for their treatment were calculated. The sewerage system selected for the study is located in the eastern part of Poland, in the Lublin Voivodeship, within the Jastków Commune. The design average daily inflow of wastewater to the classical treatment plant with activated sludge is 1200 m3·d-1. To the sewage network made of PVC with a length of 67.22 km domestic wastewater from 1119 single-family buildings from 3350 residents are discharged. The study was carried out in 2019–2022, and the daily precipitation totals and daily sewage inflows to the treatment plant were analyzed. The results of the calculations were related to the humidity classification of the year (dry, average and wet) under temperate climate conditions. The study showed that during precipitation events, the share of incidental water in the average daily volume of wastewater flowing into the treatment plant ranged from 3 to 26%. Annually, 7,400 to 10,325 m3 of rainwater flowed into the studied treatment plant, which accounted for 5.0 to 6.3% of the annual volume of wastewater. The incidental waters flowing into the sewage system resulted in the need to spend additional sums – from PLN 47,814 (€10,897) to PLN 71,232 (€16,234) per year. Thus, the annual cost of wastewater treatment in the studied system increased by about 5–6%. The results of the study are important and valuable information for the operators of the analyzed sewerage network and the wastewater treatment plant, as well as for other units that use similar systems. They will allow to initiate actions to detect and eliminate illegal connections of roof gutters and/or yard drains to sanitary sewers in the analyzed area, which would then allow to reduce the cost of wastewater treatment in the studied case.

12

Spatiotemporal relationship of temperature and precipitation over southern coasts of the Caspian Sea based on quantile regression methods

Solaimani Karim, Ahmadi Sedigheh Bararkhanpour

Acta Geophysica

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2024

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Vol. 72, no. 2

1127--1142

EN

Temperature and precipitation are significant environmental variables that can lead to catastrophic climatic disasters. The intensity of precipitation increases with increasing temperature under humid conditions. As a result, investigating the trend and relationship between precipitation and temperature is important in a wide range of industries such as trade, agriculture, and ecological analysis. Quantile regression techniques were used in this study to determine the effect of temperature variables on different amounts of precipitation during a 36-year duration (1984-2019) in Mazandaran Province of Iran. According to the findings, heavy rainfall increased significantly in February and April while decreasing in May, June, and September. All minimum and maximum temperature measurements, however, increased significantly. Moreover, the positive and negative effects of temperature variables were higher in the upper quantiles of precipitation, so the most negative effect of the minimum temperature were identified in the northwestern regions and in the warm and cold months of the year, but the most positive effect were detected in the north. In contrast, it was revealed that the north and northwest regions, respectively, were most negatively impacted by maximum temperature and most positively impacted by heavy rainfall. Finally, in a long period, high temperatures have not shown a positive effect on precipitation, and it is different according to spatial and temporal changes.

13

Characterizing spatiotemporal properties of precipitation in the middle Mahanadi subdivision, India during 1901-2017

Sahu Ramgopal Tilakram, Verma Shashikant, Verma Mani Kant, Ahmad Ishtiyaq

Acta Geophysica

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2024

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Vol. 72, no. 2

1143--1158

EN

Long-term historical data and their interpretation are crucial aspects of understanding any kind of variation that exists as a result of changing environmental behaviour. The focus of the study is to characterize precipitation properties in the middle subdivision of the Mahanadi River basin (MRB). An eigen-based technique, also known as the maximum loading value approach, and gridded precipitation data with a resolution of 0.25° X 0.25° are presented to analyze the spatiotemporal properties of precipitation at different timeslot intervals. The meteorological data (gridded precipitation for 117 years from 1901 to 2017) has a special “k” field for spatial and temporal modes of spatial pattern analysis, which aids in the recognition of precipitation properties. The identified characteristics of the exclusive timeslot periods have been assessed for any dispersion as a function of annual precipitation. To cross-validate the identified patterns for distinctness and pairwise comparison, the Kolmogorov-Smirnov’s D test was used. Southwest Mahanadi does not experience much variation in pattern size (± 3-5%), with a maximum variance of 39.09% during timeslot 2 (1940-1978). Similarly, the southeast Mahanadi observed a continuous increase in pattern size and was above 10% with a maximum variance of 28.53% during timeslot 3 (1979-2 017). While north-eastern Mahanadi experienced a continuous and significant decrease of > 14% of the total variance, with a maximum (42.48%) during timeslot 1 (1901-1939) and a minimum (28.14%) during timeslot 3 (1979-2017). There is no spatial pattern variability from summer to any of the timeslot intervals.

14

Characteristic of regional groundwater flow system: case modeling study in Longzici karst spring area, North China

Qiao Xiaojuan, Cheng Yu, Wang Dawei

Acta Geophysica

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2024

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Vol. 72, no. 1

323--339

EN

Karst spring water dynamic characteristics and its response to atmospheric precipitation are of great significance for water resources utilization under the background of climate change. This paper selects Longzici spring area, North China, as the study area. Based on a long series of spring water flow and precipitation data, the dynamic characteristics of spring flow were analyzed and the numerical simulation of the groundwater flow model was established. The results show that the groundwater kept the sustained decline over the past decades which is in a negative equilibrium state, with a storage variable of - 2.26 million m3/year. The sensitivity of spring flow to precipitation under different precipitation scenarios shows that the water level changes in the recharge and drainage areas are similar about (3-5 cm) and slightly larger than that in the runoff area(1.5 cm) when minimum rainfall (287.24 mm) happens. When the precipitation is at its maximum (867.66 mm), the water level change in the runoff area can reach 95 cm which is much larger than those in the recharge and discharge areas. The results indicate that Longzici karst spring has a relatively good regulation water resource capacity and the runoff area is more sensitive which plays an important role in response to climate change.

15

Assessing the variability of satellite and reanalysis rainfall products over a semiarid catchment in Tunisia

Gharnouki Ines, Aouissi Jalel, Benabdallah Sihem, Tramblay Yves

Acta Geophysica

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2024

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Vol. 72, no. 2

1257--1273

EN

Precipitation is a key component in hydrologic processes. It plays an important role in hydrological modeling and water resource management. However, many regions suffer from limited and data scarcity due to the lack of ground-based rain gauge networks. The main objective of this study is to evaluate other source of rainfall data such as remote sensing data (three different satellite-based precipitation products (CHIRPS, PERSIANN, and GPM) and a reanalysis (ERA5) against groundbased data, which could provide complementary rainfall information in semiarid catchment of Tunisia (Haffouz catchment), for the period between September 2000 and August 2018. These remotely sensed-data are compared for the first time with observations in a semiarid catchment in Tunisia. Twelve rain gauges and two different interpolation methods (inverse distance weight and ordinary kriging) were used to compute a set of interpolated precipitation reference fields. The evaluation was performed at daily, monthly, and yearly time scales and at different spatial scales, using several statistical metrics. The results showed that the two interpolation methods give similar precipitation estimates at the catchment scale. According to the different statistical metrics, CHIRPS showed the most satisfactory results followed by PERSIANN which performed well in terms of correlation but overestimated precipitations spatially over the catchment. GPM underestimates the precipitation considerably, but it gives a satisfactory performance temporally. ERA5 shows a very good performance at daily, monthly, and yearly timescale, but it is unable to represent the spatial variability distribution of precipitation for this catchment. This study concluded that satellite-based precipitation products or reanalysis data can be useful in semiarid regions and data-scarce catchments, and it may provide less costly alternatives for data-poor regions.

16

Application of hierarchical cluster analysis to spatiotemporal variability of monthly precipitation over Khyber Pakhtunkhwa, Pakistan

Tajbar Sapna, Tajbar Asfandiyar, Pashaie Zahra, Khorshiddoust Ali Mohammad, Rafiq Lubna

Acta Geophysica

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2024

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Vol. 72, no. 2

1159--1174

EN

Understanding the long-term spatiotemporal variability of precipitation at the regional scale is critical for developing flood and drought control strategies and water resource management. This study assessed the spatiotemporal variability of monthly precipitation over the Khyber Pakhtunkhwa province of Pakistan for 1998-2019 using hierarchical cluster analysis to cluster 156 Tropical Rainfall Measuring Mission grids. Statistical properties of clusters were calculated and the relationship of geographical features such as latitude, longitude, and altitude and statistical variables including standard deviation, maximum and minimum precipitation, and coefficient of variation (CV) with average precipitation was assessed. Findings showed that northeast parts received maximum precipitation while north and southern regions received less precipitation. Temporal analysis showed two clusters of rainy months (February, March, April, May, July, and August) and dry months (January, June, September, October, November, and December). The region was divided into two homogeneous precipitation regions. From January to April and November to December, cluster 1 occupied northern parts with maximum average precipitation while cluster 2 southern parts. From June to September, cluster 2 covered the northeast and southern parts with the highest average precipitation. During May, cluster 2 received the highest average precipitation in the northeast and southeast parts, whereas cluster 1 covered the northwest and southwest. In October, cluster 2 received maximum average precipitation covering the northeast. CV suggested higher temporal variability in cluster 2 (67.75-102.36)% than cluster 1 (65.82-99.55)%. Precipitation correlation showed that CV opposed the longitude and averages, whereas latitude and altitude demonstrated minimal correlations. These insights can assist decision-makers in devising suitable strategies to plan and control unexpected volumes of precipitation.

17

Seasonality and long-term trends of NDVI values in different land use types in the eastern part of the Baltic Sea basin

Klimavičius Laurynas, Rimkus Egidijus, Stonevičius Edvinas, Mačiulytė Viktorija

Oceanologia

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2023

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Vol. 65 (1)

171--181

EN

This study analyses changes in Normalized Difference Vegetation Index (NDVI) values in the eastern Baltic region. The main aim of the work is to evaluate changes in growing season indicators (onset, end time, time of maximum greenness and duration) and their relationship with meteorological conditions (air temperature and precipitation) in 1982–2015. NDVI seasonality and long-term trends were analysed for different types of land use: arable land, pastures, wetlands, mixed and coniferous forests. In the southwestern part of the study area, the growing season lasts longest, while in the northeast, the growing season is shorter on average by 10 weeks than in the other parts of the analysed territory. The air temperature in February and March is the most important factor determining the start of the growing season and the air temperature in September and October determines the end date of the growing season. Precipitation has a much smaller effect, especially at the beginning of the growing season. The effect of meteorological conditions on peak greenness is weak and, in most cases, statistically insignificant. At the end of the analysed period (1982–2015), the growing season started earlier and ended later (in both cases the changes were 3–4 weeks) than at the beginning of the study period. All these changes are statistically significant. The duration of the growing season increased by 6–7 weeks.

18

Long-term precipitation events in the eastern part of the Baltic Sea region

Mačiulytė Viktorija, Rimkus Egidijus, Valiukas Donatas, Stonevičius Edvinas

Oceanologia

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2023

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Vol. 65 (1)

141--150

EN

Precipitation anomalies have a significant impact on both natural environmental and human activity. Long lasting drought analysis has received great attention on a global and regional scale while prolonged rainy periods so far have been much less studied. However, long-term precipitation events are also important and threatening. The situation around the Baltic Sea in 2017 revealed that such periods could cause significant losses in agriculture. The rainy periods of 30, 60, and 90 consecutive days in a given year during which the maximum precipitation amount was recorded in the eastern part of the Baltic Sea region were analysed in this study. Daily precipitation amount data from the E-OBS gridded dataset was used. The investigation covered a period from 1950 to 2019. The changes in magnitude and timing of such rainy periods were evaluated. It was found that the annual precipitation in the eastern part of the Baltic Sea region increased significantly during the analysed period. Positive changes were observed throughout the year except during April and September. The amounts of precipitation during rainy periods of different duration also increased in most of the investigated areas but changes were mostly insignificant. Consequently, a decrease in the ratio of precipitation amount during the rainy period to annual precipitation was observed. It was also found that the rainy periods occurred earlier, especially in the case of the rainy periods of 60- and 90-days durations. Such tendencies pose an increasing threat to agriculture.

19

Comparison and combination of interpolation methods for daily precipitation in Poland: evaluation using the correlation coefficient and correspondence ratio

Konca-Kędzierska Krystyna, Wibig Joanna, Gruszczyńska Marta

Meteorology Hydrology and Water Management. Research and Operational Applications

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2023

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Vol. 11, Iss. 2

1--27

EN

Interpolation of precipitation data is a common practice for generating continuous, spatially-distributed fields that can be used for a range of applications, including climate modeling, water resource management, and agricultural planning. To obtain the reference field, daily observation data from the measurement network of the Institute of Meteorology and Water Management – National Research Institute was used. In this study, we compared and combined six different interpolation methods for daily precipitation in Poland, including bilinear and bicubic interpolation, inverse distance weighting, distance-weighted average, nearest neighbor remapping, and thin plate spline regression. Implementations of these methods available in the R programming language (e.g., from packages akima, gstat, fields) and the Climate Data Operators (CDO) were applied. The performance of each method was evaluated using multiple metrics, including the Pearson correlation coefficient (RO) and the correspondence ratio (CR), but there was no clear optimal method. As an interpolated resulting field, a field consisting of the best interpolations for individual days was proposed. The assessment of daily fields was based on the CR and RO parameters. Our results showed that the combined approach outperformed individual methods with higher accuracy and reliability and allowed for generating more accurate and reliable precipitation fields. On a group of selected stations (data quality and no missing data), the precipitation result fields were compared with the fields obtained in other projects-CPLFD-GDPT5 (Berezowski et al. 2016) and G2DC-PLC (Piniewski et al. 2021). The variance inflation factor (VIF) was bigger for the resulting fields (~5), while for the compared fields, it was below 3. However, for the mean absolute error (MAE), the relationship was reversed - the MAE was approximately half as low for the fields obtained in this work.

20

Assessing the impact of climate change on discharge in the Horyn River basin by analyzing precipitation and temperature data

Lobodzinskyi Oleksandr, Vasylenko Yevheniia, Koshkina Olha, Nabyvanets Yurii

Meteorology Hydrology and Water Management. Research and Operational Applications

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2023

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Vol. 11, Iss. 1

93--106

EN

It is important to investigate the hydrological consequences of current climate change. Hydrological responses to climate warming and wetter conditions include changes in discharge (frequency, amplitude, and volume). This paper describes current climate change and its impact on hydrological flow within the Horyn River basin. Daily air temperature and precipitation data obtained from the 17 meteorological stations located in and nearby the Horyn River basin, in combination with hydrological data (such as daily water discharges obtained from 9 water gauges), were used for the analysis of climate variability and its hydrological consequences. Analyses of meteorological variables and water discharges are crucial for the assessment of long-term changes in the river regime. Thiessen polygons were used to determine the area of influence of assigned specific meteorological stations, which affect the river’s catchments within the Horyn River basin. As a result of the trend analysis, it was observed that discharge within the Horyn River basin decreased over time. These results were congruent with the trends of precipitation data and air temperature data of the stations determined by the Thiessen polygons and basin boundaries. To understand current changes in the daily flow in the basin, changes in air temperature and precipitation for the period 1991-2020 were compared with the period of the climatic norm (1961-1990). A similar analysis was done for daily water discharges. Increasing air temperature and decreasing precipitation in the current period led to a significant decrease in discharges in the Horyn River basin, especially during the spring flood period.