- No. 2(2) 2022
«Meteorology. Hydrology. Environmental monitoring»
“ATMOSPHERIC RIVERS: POTENTIAL INFLUENCE ON ATMOSPHERIC PROCESSES AND METEOROLOGICAL PHENOMENA OVER THE TERRITORY OF UKRAINE
The article presents an overview of publications on the atmospheric rivers (AR) issue. AR events in recent years have got more attention from researchers due to the association with extreme precipitation. Several parameters are used to identify AR event, such as integrated water vapor (IWV) and integrated water transport (IVT). Several approaches to identifying and tracking AR have been developed and mentioned in this article. The foreign experience regarding AR connection with the general circulation of the atmosphere was analyzed. Most of the research on AR are devoted to the Eastern North Pacific and the North Atlantic regions. The key role in the variation of AR occurrence over different areas of those two regions is given to the interaction of the atmospheric circulation patterns, such as Arctic Oscillation and the Pacific North American Oscillation in the North Pacific region, and in the North Atlantic by the Arctic and North Atlantic Oscillation. There also stable connections of the AR phenomenon with the El Niño –Southern Oscillation and the Madden — Julian Oscillation are noted. A significant part of the works is devoted to studying AR influence on pre- cipitation extremes. AR is typically associated with a low-level jet stream and is formed in the warm conveyor belt zone of a cyclone, mainly in extratropical latitudes. An overview of modern research on atmospheric moisture and the heavy precipitation formation conditions over the territory of Ukraine shows that the vast majority of scientific works are based on the series of individual cases, and therefore cannot give an answer to the question of the potential role of AR or moisture advection in the processes of precipitation formation on a regional scale in the climatic aspect. The relevance of studying the AR issue consists of three aspects: the connection of AR events with large-scale circulation; the role of AR in the transport of moisture at the macro- and mesoscale levels; the connection of the AR with extreme and dangerous meteorological phenomena, in particular, heavy precipitation.
“SPECTRAL MICROPHYSICAL CLOUD MODEL FOR ASSESSMENT OF PARAMETERIZATION OF WARM CLOUD AND PRECIPITATION FORMATION PROCESSES IN MODELS WITH BULK MICROPHYSICS
Several series of numerical experiments were conducted using the one-dimensional spectral microphysical cloud model developed at UkrHMI for marine stratiform-convective clouds of the surface layer and diagrams were constructed to determine the coefficients of coagulation of cloud droplets and precipitation drops. The rates of autoconversions, accretion, and sedimentation were estimated based on generalized (bulk) parameterizations of microphysics from regional atmosphere models (Kessler, Beheng, and Khairutdinov-Kogan) and corresponding characteristics from the spectral (bin) cloud model. The obtained results have been analysed and the limits where the bulk parameterizations can be applied have been determined. Based on spectral model estimations new nonlinear formulations are proposed for parameterizations of sedimentation rates of droplet concentration and water content in models with bulk microphysics, but they need further approbation and estimation of biases against experimental measurements. Evolution in time and at vertical cloud levels of precipitation drops’ spectra are presented and analysed showing more natural two maxima shapes observed in clouds as a rule.
“FEATURES OF THE CURRENT STATE OF THE TEMPERATURE-HUMIDITY REGIME OF UKRAINE SINCE THE BEGINNING OF THE XXI CENTURY UNDER THE INFLUENCE OF CHANGES OF LARGE-SCALE ATMOSPHERIC CIRCULATION
The current state of the temperature and humidity regime of the territory of Ukraine from 1991 to the present time under the influence of changes in large-scale atmospheric circulation is considered. The atmospheric circulation model by V. Martazinova and the EOF decomposition of pressure fields, the beginning of the formation of the modern climate regime since 2006 was determined. For the analysis of the modern temperature-humidity regime, the data of the fields of air temperature, atmospheric precipitation, pressure, geopotential in the nodes of the geographic grid of the Atlantic-European sector of the archive of UkrGMI-СDDPP; NOAA Northern Hemisphere Archive; air temperature, precipitation, direct solar radiation of Ukrainian stations since 1991 were used. It is established that the temperature since the beginning of our century on the territory of Ukraine is growing, dry processes with deficit of precipitation are observed in April, August and September. The increase of the drought processes affects the current state of direct solar radiation, which for the warm period of the last 15 years exceeds the norm of previous years almost in all territory of Ukraine, especially in the northern and central regions.
“THE OPTIMAL SETTINGS FOR THE ONLINE-INTEGRATED MODEL ENVIRO-HIRLAM IN ORDER TO SIMULATE THE ATMOSPHERE-CHEMISTRY INTERACTION FOR THE UKRAINIAN TERRITORY
The necessity of studying complicated feedbacks in the atmosphere and their further implementation in numerical models caused the development of online-integrated modelling. Due to the requirements of huge computer resources, this type of modelling is still not broadly available in Ukraine. The paper presents the analysis of optimal settings and input data towards the use of the online-integrated model Enviro-HIRLAM for the Ukrainian territory. Enviro-HIRLAM could be used to simulate the complicated atmosphere-chemistry interaction and include the role of direct and indirect aerosol effects on the atmospheric processes. Based on the numerous simulations using Enviro-HIRLAM while conducting two HPC-Europa3 projects, the optimal settings and input data for the Ukrainian territory were found. It is possible to define standard boundaries for a domain covering the entire Ukrainian territory with 5-km horizontal resolution. This domain does not depend on prevailing synoptic processes because it is used as a downscaling from the 15-km resolution domain, which covers large territories and considers atmospheric circulation. Further downscaling to 2 km and 1.5 km horizontal resolution allows studying the urbanization effects on the atmosphere. The paper describes settings which depend on available computer resources: dynamic time step, number of tasks and nodes, number of sub-domains, etc. We present the possible datasets which could be used for meteorological and atmospheric composition initial and boundary conditions for the Ukrainian territory. Moreover, the possible land-use/ land cover datasets and emission inventories are also given. Overall, this setting and input data allow users to run Enviro-HIRLAM using modes which include direct, indirect, or both (direct + indirect) aerosol effects. However, the control run is preferable for result comparison.
“PREDICTION OF GROUNDWATER FLOW TO THE SOUTH BUG RIVER USING ARTIFICIAL NEURAL NETWORKS AND REGRESSION EQUATIONS
The most reliable forecasts can be obtained for hydrogeological objects that have signs of determinism in regime changes. First of all, these include systems with an undisturbed mode. However in the network of state hydrogeological monitoring of groundwater, there are no objects with an undisturbed regime due to the spread of direct anthropogenic influence and indirect - due to the changes in climatic conditions caused by it. Significant variability and unpredictability of changes in traditional regime-forming factors (air temperature and precipitation) over the last decades proves the low efficiency of forecasting the level and flow of groundwater using empirical regression equations built on data from the 1980s - early 2000s. It was possible to obtain more reliable results with the help of neural network modelling, which involves working with significant series of contradictory data that change according to an unknown algorithm. The forecast was made for the specific underground flow to the South Bug River in the area of Khmilnyk. The advantages of simulated forecasting over time series forecasting are shown.
“SIGNATURES OF WILDFIRES CAUSED BY HOSTILITIES USING THE RESULTS OF SPACE PHOTOGRAPHY
There are no scientific works to present date, which would reveal the issue of separating fires from atypical causes from others caused by economic and recreational activities, using satellite infrared imaging. The purpose of this study is to establish the special deciphering signatures of atypical fires. Deciphering fires is their classification according to a number of characteristics: area, power, contour configuration, etc. For this research we used the data from FIRMS (Fire Information for Resource Management System) supplied by NASA, USA. Fire monitoring was daily carried out, starting in April 2020 when intense forest fires began in Ukraine, including the period of russian aggression, until September 2022. There are compared the data from space imagery in the infrared spectrum, visible (mid-resolution daytime space images) and news in mass media. For each fire there are calculated the area using the extreme points of the contour and the total power of the hot spots that fell into this contour. The data were received twice a day for each fly-around of the satellites. A number of criteria were identified which indicate the military origin of fires. These are fires in built-up areas, the irregular shape of fires contours, coverage of territories with different types of land use, too powerful ignitions and fires at an atypical time for the area. We can consider with a high probability that fires which have economic and recreational origin are arisen at the places of previous fires and which spread gradually over several days, and fires of low and medium power outside the collision zone. For the first time, the analysis of fires based on the results of space photography during the military conflict was performed and decipherable signs of fires from combat operations were identified. There are the conclusion that the results of this study may be needed to determine the amount of damage caused by russian aggression.
“HYDROMORPHOLOGICAL MONITORING OF SURFACE WATERBODIES: SURVEYPROTOCOL
The process of the water resources management system reforming is taking place in Ukraine according to the Water Framework Directive requirements. New order of the state monitoring of water has come into force on January 1, 2019. Monitoring program includes observations of biological, physico-chemical and hydromorphological parameters. Development of the uniform site investigation protocol is an important stage of hydromorphological monitoring. Such a protocol should be obligatory for the hydrometeorological organizations of the State Emergency Service of Ukraine which are dealing with hydromorphological monitoring. Parameters and characteristics included into the site investigation protocol providing general information concerning the main unit of hydromorphological monitoring of the surface water body of “River” category – channel section, are described in the paper.
“AVERAGE LONG-TERM VALUES AND VARIABILITY OF WATER, SALT AND DISSOLVED NUTRIENT FLOWS IN THE SYSTEM OF THE DNIEPER-BUG ESTUARY
Riverine input of dissolved nutrients (phosphorus and nitrogen) to the NW Black Sea shelf plays the main part in the marine water eutrophication. Between the rivers’ fresh water and open sea’s saline water, transient estuarine systems may be partial consumer or producer of nutrients. To obtain mean multiannual estimates of nutrients transport and metabolism in the largest estuarine system of Dnipro and South Bug rivers (Dnipro-Bug liman, DBL), regular observational data of 1992-2018 were collected and widely known LOICZ biogeochemical modelling approach and software were applied. Box model of water and substances transport was constructed consisted of two connected one-layer boxes. Each box has the entrance from the river and exits: from the first box – to the second one, and from the second box – to the adjacent sea. Using this model, the flows of water, salts and nutrients (dissolved inorganic phosphorus and nitrogen, DIP and DIN) were calculated. Non-conservative substance remnants, which are determined by internal biogeochemical (non-hydrographic) interactions were interpreted using Redfield’s relations. Fluxes of groundwater, precipitations and evaporation were found to be neglectable comparing to riverine input and water exchange fluxes. It was established that the nutrients outputs from the DBL to the sea are: 89,3 % of DIP and 41,4 % of DIN in relation to the total volume of these substances’ inflow to the DBL with river run-off. In general, in the DBL primary production outweighs the respiration, and denitrification significantly outweighs the nitrogen fixation. Numerical estimates of the DBL model correspond to the average long-term state. But it is available to analyze the response of the results on the input data variability by evaluating uncertainty using the Monte-Carlo (MK) method. According to MK-estimates, most variables of the DBL box model can vary on average in the range of only 19 – 25 % of their mean values, despite the large variability of nutrient inputs with riverine flows.
