Northwestern Wind Research Articles

Transboundary migration of Loxostege sticticalis (Lepidoptera: Crambidae) among China, Russia and Mongolia.

The beet webworm, Loxostege sticticalis, a worldwide pest of many crops, performs a seasonal migration, causing periodic outbreaks in Asia, Europe and North America. Although long-distance migration is well documented in China, patterns of transboundary migration among China, Russia and Mongolia are largely unknown. We performed a phase analysis of L. sticticalis periodic outbreaks among three countries based on 30 years of historical population data, analyzed the wind systems during migration over boundary regions, and traced the migratory routes in a case study of outbreaks in 2008 by trajectory simulation. Highly synchronized outbreak years of L. sticticalis were observed between China and Mongolia, China and eastern Siberia, China and western Siberia, Mongolia and eastern Siberia, eastern Siberia and western Siberia from 1978 to 2008, indicating possible transboundary migration between these regions. Winds at 300-600 m altitude, where adult migration usually occurs, also showed a high probability of northwestern winds in Haila'er (China), Chita (Russia) and Choybalsan (Mongolia), favoring successful adult migration from these areas to northern and northeastern China. Back trajectory analysis further showed that the first-generation adults that caused the severe outbreak of second-generation larvae in 2008 originated from eastern Siberia, eastern Mongolia, and the boundary regions of China-Russia and China-Mongolia. Our findings demonstrated that the source of L. sticticalis outbreaks in northern China was closely related to the outbreaks in Siberia and Mongolia via long-distance transboundary windborne migration. This information will help guide international monitoring and management strategies against this notorious pest. © 2024 Society of Chemical Industry.

Effect of wind–wave conditions on the distribution of the phytoplankton community in the coastal area of the southern Crimea in spring (Black Sea)

Based on the measurement data obtained during the 121th cruise of the RV Professor Vodyanitsky, regularities were established between spatial distribution of quantitative characteristics and phytoplankton species composition, chlorophyll a concentration, and hydrometeorological parameters of the environment on the southern Crimean coast in the spring 2022. Chlorophyll a concentration was compared with satellite observation data of high spatial resolution. In selected areas with different shelf depths, the features of the distribution of phytoplankton indicators under conditions of changing hydrometeorological parameters were studied. The mechanisms of vertical water exchange were described. In coastal waters of the Crimea (Foros–Novy Svet), with intense western wind contributing to Ekman upwelling and low water temperature is a consequence of the upwelling, rather high values of phytoplankton biomass and abundance and chlorophyll a concentration were recorded, which were accompanied by the highest values of oxygen content. In the area of Sudak–Feodosiya, with intense northeastern wind and waves and with quite high water temperature, low dissolved oxygen, low values of phytoplankton biomass and abundance and chlorophyll a concentration were registered. Apparently, in Sevastopol area, Ekman upwelling arises under the effect of northern and northwestern winds. In three regions, dinoflagellate microalgae prevailed in spring 2022 in phytoplankton biomass. Those accounted for 52, 66, 81 % of the total number of species identified in the regions: Foros–Novy Svet, Sudak–Feodosiya, near Sevastopol, respectively. Thus, the main mechanisms were analyzed, which drive spatial distribution of quantitative characteristics and species composition of the phytoplankton community in the Crimean coastal water area with different shelf depths in spring.

Vostok Bay: interseasonal changes in hydrological, hydrochemical and microbiological properties

Current ecological state of the Vostok Bay (Peter the Great Bay, Japan Sea) in spring, summer, and autumn seasons is described on the data of CTD profiling, chemical analysis of the water sampled at the sea surface and bottom, and microbial indication of the surface water. Strong seasonal variations are revealed for all examined parameters, driven by monsoon cycle. The winter monsoon in autumn with northwestern wind predominance causes the river runoff weakening and off-shore surge with the water removal from the top of the bay and the compensating inflow along the eastern coast distinguished by heightened values of salinity and dissolved oxygen and low values of biochemical oxygen demand (BOD5 < 1 mg/L). The summer monsoon in spring and summer with southeastern winds increases the river runoff and simultaneously the inflow of fresh water from the open sea, so causes a sharp difference in the water properties between parts of the Vostok Bay. Bioproductivity increases in these seasons that is reflected in increasing of BOD5 (up to 2 mg/L and sometimes more) and organic phosphorus concentration (up to 50 μg/L and more). In July, when the river runoff is blocked in the northwestern sector of the bay by onshore surge, the maximum number of bacteria is recorded there (up to 105 CFU/mL), including Escherichia coli group at all coastal stations in concentrations of 10–100 CFU/mL, which are not observed in the central and open parts of the bay. Among the groups of metal-resistant microorganisms, relative abundance of nickel-resistant bacteria is noted (up to 103 CFU/mL) that is a sign of hydrocarbon fuels combustion. The hydrocarbon pollution is confirmed by ubiquitous distribution of oil-oxidizing and diesel-resistant microorganisms detected mostly (up to 2.8 ∙ 104 CFU/mL in summer) in the northern part of the bay. Generally, the internal northern part of the bay is distinguished by high abundance of microorganisms belonged to different ecological and trophic groups, because of mutual impacts of the rivers, the coastal highway, nearby settlements, and sandy beaches occupied by vacationers in summer.

Understanding the Characteristics of Vertical Structures for Wind Speed Observations via Wind-LIDAR on Jeju Island

Wind observations at multiple levels (40–200 m) have been conducted over a five-year time period (2016–2020) on Jeju Island of South Korea. This study aims to understand the vertical and temporal characteristics of the lower atmosphere. Jeju Island is a region located at mid-latitude and is affected by seasonal wind. The maximum wind speed occurs in the relatively lower altitudes during daytime and is delayed in the relatively higher altitude after sunset in a diurnal cycle. In the summer season, the altitudes appear earlier than in other seasons via the dominant solar radiation effect during daytime, and the altitude after sunset increases up to 160 m. However, the maximum wind speed in the winter season occurs irregularly among altitudes, and it is lower than that in the summer season. This can be attributed to the increase in the mean wind speed in the diurnal cycle caused by the strong northwestern wind in the winter season. These results imply that the relationship between near-surface and higher altitudes is primarily affected by solar radiation and seasonal winds. These results are expected to contribute to site selection criteria for wind farms.

Earliest cereal cultivation in Egypt recorded in the Faiyum Oasis lake deposits and its palaeoclimatic context

We determine the beginning of the Neolithic farming in northern Egypt, based on analysis of core FA-1 of lake deposits in the Faiyum Oasis in northern Egypt. Regular lamination of the early Middle Holocene lake deposits, supported by radiocarbon dating and pollen analysis, indicates the earliest occurrence of domesticated cereals at ~7.8 cal ka BP in this region. The appearance of cereals in the Faiyum region was possible due to fundamental restructuring of regional climatic conditions caused by the changing atmospheric circulation in the eastern Mediterranean region. Stronger northwestern winds were accompanied by increased precipitation in winter and enabled 3 farming phases in the Faiyum Oasis at 7.8–7.6, 7.4–7.2 and 7.0–6.8 cal ka BP, separated by arid episodes with predominant southern winds. Most probably, cereal cultivation concentrated inside local wadis to the north of the lake and was rainfall-dependent. Therefore, early Egyptian farming did not develop based on irrigation systems as commonly thought, but was rain-fed, this being possible due to marked climate change at the beginning of the Middle Holocene.

Spatio-temporal Variation of Meteorological Influence on PM2.5 and PM10 over Major Urban Cities of Bangladesh

A detrended seasonal analysis on a 6-year (2013–2018) dataset of daily Particulate Matter (PM) concentration and meteorological parameters is performed to understand the spatio-temporal variation of PM and the seasonal influence of meteorological factors on PM pollution over 6 major urban cities of Bangladesh. Cross-correlation and multiple non-linear regression (MNLR) of air quality and meteorological data were used to explore the meteorology-PM interactions and their spatio-temporal variability. Meteorological influence on PM was found to be stronger in the southern part of the country relative to the northwestern part. MNLR analysis implied that meteorological parameters could explain up to 39% of daily PM variability during high pollution days. The deposition effect of relative humidity was prominent during the premonsoon season, while rainfall impact becomes dominant in the monsoon season, specifically in the northeastern region. Wind speed was observed to have a dilatory effect on PM variation, although wind seemed to carry sea aerosol in southern regions. In addition, the northwestern wind appeared to contribute to PM rise in most urban areas by carrying PM loading. In winter, the low temperature was found to favor PM accumulation, while in monsoon, high temperature causes PM rise, possibly by assisting atmospheric secondary aerosol formation. Solar radiation positively influenced atmospheric PM formation, and the influence was stronger in the northwestern region. It is shown that meteorological parameters influence the seasonal variability of PM, but the extent of this influence varies depending on temporal and regional factors.

Local production, downward and regional transport aggravated surface ozone pollution during the historical orange-alert large-scale ozone episode in eastern China

Increasing severe and persistent ozone pollution in China has resulted in serious harm to human health in recent years, yet the precise pollution sources are poorly known because there is few knowledge on large-scale extreme ozone episodes. Here, we studied the formation of the historical orange-alert regional ozone episode in eastern China on 6 June, 2021, by combining process analysis, integrated source apportionment modelling, and chemical and meteorological data. Results show that during the pollution episode, 94% of cities in eastern China suffered ozone pollution, and 39% had daily maximum 8-h average ozone concentrations higher than 100 ppb. This is explained by favorable local ozone formation and transports provided by the prevailing northwestern winds in the upper air, and by sinking atmospheric motions favoring the persistence of high surface ozone concentrations. During daytime, local photochemical production induced an ozone increase of 0.3–28.4 ppb h−1 and vertical transport induced an ozone increase of 0.4–56.1 ppb h−1. As a consequence, vertical downward transport of ozone generated in the upper air by photochemical reactions aggravated surface ozone pollution. Surface ozone concentrations include 25.8–53.9% of ozone from local provincial emissions, 0–42.6% of ozone from inter-regional transports from neighboring regions, 4.6–23.1% of ozone from outer-regional transport, and 13.6–52.9% of ozone from boundary conditions in the selected cities. Overall, our findings show that favorable meteorological conditions promoted the chemical productions of ozone on the surface and at high altitudes, thus resulting in this heavy ozone pollution. In addition, regional and vertical downward transports of aloft ozone further aggravated the surface ozone pollution, leading to the large-scale extreme ozone pollution episode.

Investigation on the difference of PM2.5 transport flux between the North China Plain and the Sichuan Basin

In this study, an advanced transport flux method based on the comprehensive stereoscopic observation verification was used to evaluate the contribution of transport to pollution in the North China Plain (NCP) and Sichuan Basin (SCB). The simulations were verified using fixed-point lidar and satellite observations, and the results demonstrated that the modeling flux calculation method was suitable for investigating the evolutionary trend of PM2.5 flux. The monthly inflow, outflow, and net flux indicated the intensive interactions and significant temporal and spatial variations of PM2.5 transport though the boundary segment of the city and region. In both autumn and winter, the Beijing-Tianjin-Hebei (BTH) region always played the role of “source” region, while Cheng-Yu (CY) region principally acted as a “convergence” region. In autumn and winter, the BTH region was controlled by a cold front weather system, and the pollutants were readily transported to the surrounding areas. However, the CY region was affected by the complex terrain, with small wind speeds near the ground and poor horizontal diffusion. The upper air was controlled by the northwestern winds behind the trough, and the air subsidence is substantial. The combined action of horizontal and vertical wind directions caused the accumulation of pollutants in the basin. Notably, one intrinsic transport pathway during two representative months was identified based on the investigation of cross-city and cross-region transport, namely the southwest–northeast (SW–NE) pathway in the BTH region. In the CY region, the northeastern transport pathway greatly influenced the cities in the basin. Additionally, through the analysis of the typical heavy pollution processes in the two regions, it was found that the southwest pathway of the BTH region and northeast pathway of the CY region in inter-city transport were significant factors before reaching the most severe stage of pollution.

COMPREHENSIVE ASSESSMENT OF THE IMPACT OF THE MAIN SOURCES OF EMISSIONS OF POLLUTANTS ON THE AIR QUALITY OF THE KUIBYSHEVSKY DISTRICT OF SAMARA

Introduction: Air quality in large urban settings is a considerable public health problem in Russia. Thus, identification of the main sources of pollution and qualitative assessment of their impact on air quality is of paramount importance. Aim: To perform comprehensive assessment of the influence of the main sources of pollutant emissions on air quality of atmospheric air in one of the districts in an industrial Russian city. Methods: Secondary data from the Federal State Budgetary Institution "Privolzhskoe UGMS" and the Federal State Budgetary Institution "Center of Epidemiology and Hygiene in the Samara Region" were obtained. Geographical maps, emission source location schemes, meteorological parameters, pollutant emissions and borders of sanitary protection zones of industrial enterprises were analyzed. Chromatographic, electrochemical, and photometric analysis, laboratory determination of the concentration of pollutants in the atmospheric air in different periods of the year were performed taking into account changing meteorological conditions. Results: As many as 26 % of emissions of pollutants into the atmosphere come from industrial sources while 45 % come from other anthropogenic sources including motor vehicles . Emissions from medium, small and microenterprises account for only 13 %, 9 % and 7 % of emissions, respectively. The most common pollutants were hydrogen sulfide, phenol, hydrocarbons C12-C19, formaldehyde andam- monia. Concentrations at the level of 0.2-0.4 MPC were found in most of the studied samples. In 16.4 % of the samples concentrations of hydrogen sulfide were up to 5.6 MPC. In the summer period with western and north-western winds, the concentration of pollutants was 15 % higher in all samples. In the cold period , with south-western and western winds excessive concentrations of pollutants in the atmospheric air was recorded in 23.3 % of the samples. Conclusions: Our findings suggest an adverse effect of air pollution on health of the residents of the studied district. Preventive measures in ecologically challenged areas of Samara are needed to preserve and promote health of the population.

Assessment of impact of combined heat on the environment of urbanized areas (case study of Ulan-Ude, Russia)

Combined heat and power plants (CHPP) are an important component of the energy balance in many countries. However, of all types of power plants, CHPPs have the largest impact on the environment. In recent years, the urban ecology has become one of the key indicators that determine the quality of life of city residents. The article evaluates the impact of the CHPPs in Ulan-Ude on the example of CHPP-1. The main sources of environmental pollution, and, accordingly, the zone of exposure of CHPP-1’ pollutants have been identified. Virtually the entire territory of the city of Ulan-Ude falls under this zone, but since northwestern winds prevail in this area, the north-western part of the city is most affected. Based on the results of a detailed dispersion calculation, we defined the following substances which should be monitored: nitrogen dioxide, sulfur dioxide, mineral oil, and inorganic dust (70-20% SiO2 and coal dust). The concentration of these substances in the air is significant.

Diagnostic Simulation of Water Age in Small Lake of Bosten Lake

Concerns have increased regarding water quality deterioration in arid land water. Water age is a useful indicator of the susceptibility of water bodies to water quality deterioration and is helpful for knowing the basic mechanisms governing the transport of materials through water bodies. In the current study, the spatial distributions of water age in the small lake of Bosten Lake (hereinafter referred to as small lake) were investigated with a two-dimensional hydrodynamic model built on the basis of the Environmental Fluid Dynamics Code (EFDC) model. In particular, the influences of different water flow periods, farmland drainages, and wind directions on water age distributions in the small lake were investigated. The modeled water age in the small lake has high spatial variability. The water age is maximum at the northeastern part and minimum at the center of the small lake. The water age in the small lake is lower during wet periods and gets larger for dry periods. After five years’ simulation, the average water age in the whole small lake system was 594, 684, and 794 days under wet, normal, and dry periods. Increasing the hydraulic connectivity of the small lake can reduce its water age by opening its ecological gate inflow and Ahongkou gate outflow. This is the more favorable hydraulic conditions promoting water exchange in most regions of the small lake and can be used in hydraulic engineering to improve its water age. The farmland drainages should be controlled around the small lake. The mean water age of the whole small lake under the northwestern wind is lower than that under the southwestern wind. The simulated results provide important information for comprehending the water exchange efficiency, help in discovery of areas of the small lake most likely to experience water quality degradation, and can be used to design the engineering projects to improve or protect the water environment.

Spatio-temporal Patterns and Potential Sources of Absorbing Aerosols in the Fenwei Plain

Air quality has gradually improved in many parts of China; however, air pollution is become more severe in the Fenwei Plain. Using OMI/Aura OMAERUV L2 and PM2.5 data, spatial autocorrelation analysis and back trajectory modeling were used to explore the spatio-temporal patterns of absorptive aerosols over the Fenwei Plain, and the dominant types, transmission paths, and potential source areas were identified. The main results can be summarized as follows:① Annual mean absorbing aerosol index (AAI) values increased between 2005 and 2019, with high period occurring in 2006, 2013, and 2017, with values exceeding 0.63. Xi'an and Linfen were identified as a 'high-high' cluster, with AAI showing poor spatial stability and a 15.3% increase in area over the past 15 years. In contrast, the area connecting Xi'an and Linfen, which occupies 24.2% of the total area of the region, was identified as a 'low-low' cluster, with a sharp drop of 6.2% in area; ② The Fenwei Plain has high AAI values across a large area in winter, exceeding 0.8 in Linfen and Xi'an, and 91.5% of the study area exceeding 0.6. Values were lower in spring (AAI>0.4) and autumn (AAI>0.3), with the lowest values occurring in summer. The atmospheric diffusion conditions in spring, autumn, and winter are poor, associated with anticyclonic high-pressure events. The observed high AAI values were significantly affected by atmospheric diffusion conditions, temperature, and precipitation; ③ Back trajectory and source contribution modeling showed that long-range transport of air masses from Xi'an and Linfen occurs from the northwest, and short-range transport air masses occurs from the east and south. Two long-range sand and dust source areas were determined (with northwestern and northern wind sources); two carbon source areas were identified (with eastern and southern wind sources); and one combined sand and carbon source area was identified (from the Loess Plateau). Of these sources, the northwestern wind source, the Loess Plateau, and the southern wind source have significant influence in Xi'an, and the eastern wind source and the Loess Plateau have a significant impact on Linfen. Linfen is little affected by the northwestern wind source and the dust from the northern wind source. Based on the spatial distribution of CO and its correlation with AAI, it is concluded that cardon in the dominant absorbent aerosol in Linfen dust and carbon are most important in Xi'an.

Tracking prevailing dust aerosol over the air pollution in central China with integrated satellite and ground observations

Besides intense dust storms, downstream transport of dust particles in the extensive deserts of East Asia have been rarely concerned. In this study, we present a comprehensive insight into sources, transport process, and potential influence of the prevalent dust particles in central China during October 2020 based on integrated satellite and ground observations. Although dust events are usually considered concentrated in spring, satellite observations show that dust sources are active during fall. Thick dust layers with high uplifted altitudes at ~5 km are found in their downstream path, which can be carried to northern China and even the Sichuan Basin by predominant northwestern winds at 700 hPa. Despite a lack of air masses directly from active dust sources, dust plumes from both Taklimakan Desert and Gobi deserts can be blown to central China in their transport path or when they have arrived over northern and eastern China. Unlike dust storms with strong winds cleaning local atmospheric pollutants, these floating dust plumes tend to suspend over the air pollution near surface. In particular, the slow dust-pollution mixing process in central China can last for as long as ~3–4 days due largely to the common temperature inversion in fall. Despite a dominant contribution (>50%) in particle pollution, these dust transport with much smaller scales than dust storms can be unnoticeable. Our results suggest that more attention should be paid to the role of these unnoticeable but frequent dust plumes in regional atmospheric environment and climate effects.

Thermocline Formation in the Persian Gulf

Persian Gulf (PG) is a semi-enclosed water basin that is connected to the Gulf of Oman through the Strait of Hormuz. There are different forcing and climatic parameters influencing the thermocline development in the PG from winter to summer. These factors include tide, river inflow, solar radiation, evaporation, northwestern wind, and water exchange with the Gulf of Oman. In fact, the thermocline, which is often observed in the oceans and open seas, can be considered as a seasonal phenomenon in the ocean. In the present study, it is studied theoretically; and compared with the results of the Princeton Ocean Model (POM) in the PG. During winter to summer, solar heating created an intense thermocline that decoupled the surface mixed layer from the interior water. The data are reviewed as the measurements collected in 1992 and recent modeling results. Overall, through a theoretical study, it is concluded that thermocline formation is a seasonal phenomenon in the PG.

Анализ сезонной изменчивости гидролого-гидрохимических характеристик поверхностных вод северо-западной части Черного моря

Based on the archival data set of the Institute of Natural and Technical Systems from 1955 to 2015 the intra-annual variability of temperature, salinity, dissolved oxygen and PH in the surface layer of the waters of the northwestern shelf of the Black Sea, including the Danube estuary area, is analyzed. The temperature of surface waters on the NW shelf of the Black Sea and the Danube waters differ significantly on a seasonal scale. The Danube waters considerably cool down the surface layer of the estuarine zone during the winter months. Seasonal changes in salinity are associated not only with large seasonal fluctuations in the river flow, precipitation and evaporation, but also with seasonal variability of the wind field. In the autumn period in the spatial distribution there is an increased oxygen content off the coast of Romania, which is related to the prevailing northwestern wind in this region, which leads to the drift of the transformed Danube waters along the western coast. Due to the prevalence of southeastern winds off the Romanian coast, the Danube waters are blocked in the coastal region, which is clearly seen from the spatial distribution of oxygen. The seasonal dynamics of the pH value corresponds to the development of production processes. From winter to summer, an increase in the pH value is noted in both water areas, and then its decrease by autumn. The absolute predominance of the annual harmonic in the seasonal variability of most of the analyzed hydrological and hydrochemical characteristics in most of the examined shelf water area was confirmed. The exception is the salinity in the estuary area of the Danube. The semiannual harmonic describes more than 60% of the total variance due to the seasonal variability of salinity, which is related to the peculiarities of the wind regime in the region.

Identification of intermittent point source capacity and location of the initial contamination plume

While working on a model of mass impurity transition for the waters of the Sea of Azov and the Kerch Strait, we calculated the capacity of the immediate point source and identified the location of the initial contamination plume. Contamination source capacity identification is based on minimizing the quadratic functional of the forecasting quality and solving associated problems. Associated problem solving is also used in order to identify the location of the initial contamination plume in the body of water under analysis. The first goal was reached for the Gulf of Taganrog area, and the second one – for the Kerch Strait area. It must be noted that both areas have heavy marine traffic and experience the construction of new transport corridors. Simulation results were produced taking into consideration north-western winds that are dominant in the region. Quantitative experiments show that it is possible to identify the capacity of an intermittent point source of contamination using a three-dimensional model of mass impurity migration, as well as to identify the location of the initial contamination plume.

WEATHER CONDITIONS, AIR POLLUTION, EMERGENCY CALLS AND POPULATION MORTALITY IN PETROZAVODSK

The aim of the present study is to assess the associations between weather factors, atmospheric air pollution and the number of emergency medical calls (EMC) and population mortality Petrozavodsk, Northwest Russia. Methods. Linear correlations between the monthly values of external factors, the number of EMC for people with cardiovascular diseases and the total mortality werestudied. Graphs of the long-term associations betweenmortality rates and pollutant emissions from stationary sources were constructed. Results. Longterm average annual temperature of atmospheric air increased from +3.1 °C (1994-2001) to +3.8 °C (2002-2017) and the frequency of northwestern wind (FNWWD) increased by an average of 29.5 % during the same periods. This wind direction is associated with health-related problems in the city related to the spread of emissions from stationary contamination sources. A strong statistical relationship between the annual amount of emissions and mortality coefficients (total and from diseases of the circulatory system) for the period 2002-2017 was observed. A temperature (seasonal) factor is statistically significantly (from p < 0.001 to p = 0.034) associated with frequency of EMC for essential hypertension, angina pectoris (2015-2017) and chronic coronary heart disease (2016, 2017). A positive correlation between FNWWD and the number of EMC for people with acute myocardial infarction (p = 0.015) and stroke (p = 0.011) for a three-year period (2015-2017) was revealed. Conclusions. The results of the study indicate the need to take into account the influence of weather conditions and air pollution on the frequency of emergency medical calls and the patterns of mortality in urban settings.

Specific oceanographic characteristics and phytoplankton responses influencing the primary production around the Ulleung Basin area in spring

The East Sea (Sea of Japan) is a marginal, semi-closed sea in the northwestern Pacific. The Ulleung Basin area, which is located near the subpolar front of the East Sea, is known to have high primary production and good fisheries in spring season. After episodic wind-driven events during the spring of 2017, horizontal and vertical profiles of physical chemical biological factors were investigated at 29 stations located in the Ulleung Basin area. In addition, growth responses of phytoplankton communities to nutrient additions were evaluated by bioassay experiments to understand the fluctuation of phytoplankton biomass. Because of strong northwestern wind, phytoplankton biomass was scattered and upwelling phenomenon might be suppressed in this season. The phytoplankton abundances in the coastal stations were significantly higher than offshore and island stations. In contrast, the nutrient and chlorophyll a (Chl a) concentrations and the phytoplankton biomass were quite low in all locations. Bacillariophyceae was dominated group (75.1% for coastal, 40.0% for offshore and 43.6% for island stations). In the algal bioassays, the phytoplankton production was stimulated by N availability. The in vivo Chl a values in the +N and +NP treatments were significantly higher than the values in the control and the +P treatments. Based on the field survey, the higher nutrients in coastal waters affected the growth of diatom assemblages, however, little prosperity of phytoplankton was observed in the offshore waters despite the injection of sufficient nutrients in bioassay experiments. The growth of phytoplankton depended on the initial cell density. All of results indicated that a dominant northwestern wind led to a limited nutrients condition at euphotic layers, and the low level of biomass supply from the coasts resulted in low primary production. Both supplying nutrients and introducing phytoplankton through the currents are critical to maintain the high productivity in the Ulleung Basin area of the East Sea.

Distribution of Desalinated Waters of the Amur Estuary in the Okhotsk Sea According to Satellite Observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.

The distribution of the desalinated waters of the amur estuary in the okhotsk sea according to satellite observations

The distribution of the desalinated waters of the Amur Estuary in the Northwestern ​​Okhotsk Sea during the summer period was analyzed using satellite data on sea level, salinity, temperature and concentrations of suspended organic carbon. There is good agreement between the spatial distribution of surface water salinity (data from the SMAP satellite) and the sea level (AVISO data) in the study area. The identification of the waters of the Amur Estuary by the surface water temperature and the concentration of suspended organic carbon is limited to the Sakhalin Bay and the coastal waters of Sakhalin Island. An increase (decrease) in the flow of the Amur River during the spring-summer flood leads to an increase (decrease) in sea level in the northern part of the Sakhalin Bay in July. Strengthening of the northwestern (southeastern) winds in September reduces (increases) the inflow of waters with low salinity and elevated sea level to the area north of the Sakhalin Bay.