Purpose. The paper is aimed at studying the spatial and temporal variability of a latent heat flux - one of the important components of heat balance in the northwestern Pacific Ocean and the Far Eastern seas based on the ERA5 5 reanalysis data. Methods and Results. The ERA5 5 reanalysis data on a latent heat flux in the area limited by the coordinates 42-60 degrees N and 135 -180 degrees E and including the Far Eastern seas and the northwestern part of the Pacific Ocean constituted the material for the study. The array of monthly averages at a quarter-degree spatial resolution was analyzed using the standard statistical methods. The average long-term distributions of latent heat flux values for each month were constructed; the amplitudes and phases of annual and semi-annual harmonics, and the linear trend coefficients were calculated in each spatial cell, and the decomposition was performed using the empirical orthogonal functions. The range of seasonal variations is significant in the zone of warm currents, and it sharply decreases in the northern part of the area under study in the Pacific Ocean as well as in the Okhotsk and Bering seas. The interannual variations are manifested in the quasi-cyclic changes of the envelope based on the maximum values with a period of about 6 years. The unidirectional trends in the interannual latent heat flux variations are weakly shown. Conclusions. . Among the seasonal variations of a latent heat flux, the annual cyclicity is predominant and the most pronounced in the southern part of the northwestern Pacific Ocean (the area influenced by the warm Kuroshio Current) off the Japan Sea coast of the Honshu Island in the Tsushima Current zone. This is conditioned by a significant evaporation increase in these areas during a cold season that, in its turn, is related to a sharper temperature contrast as well as to the impact of a winter monsoon characterized by the strong and stable northwesterly winds bringing dry, cold air from the continent. In a warm period, in some areas of the studied water area, the latent heat flux values are positive that indicates the important role of water vapor condensation in the areas with high cloudiness and in the zones of quasi- stationary upwellings.
Features of spatio-temporal variability of the Bering Sea surface temperature were studied by constructing long-term average distributions for different months and using the method of empirical orthogonal functions based on ERA5 reanalysis data based mainly on satellite information, for the period 1998–2020 (spatial resolution of the data is a quarter of a degree, the time interval is one month). In each spatial cell, for each month, the average long-term values of this parameter were calculated, which showed seasonal changes in thermal conditions in the studied water area. Linear trend coefficients have been determined, which showed a stable tendency to warming of the surface layer of sea waters, most pronounced in summer. Extreme deviations from the average long-term values (anomalies) of the surface temperature of the Bering Sea are considered.
An array of ERA5 reanalysis data on the sensible heat flux on the surface of the Northwestern Pacific Ocean and the Far Eastern seas for 1998–2022 is analyzed. It is shown that the positive values of this flux (directed from the atmosphere to the ocean) were observed in spring and summer, the maximum values in May were about 2 MJ/m2 in the southwestern part of the Sea of Okhotsk, and on the ocean shelf of the southern Kuril Islands and Hokkaido Island. Negative values (backflow) are observed in autumn and winter, they reach –14 MJ/m2 in December. The imbalance between these fluxes is covered by the advection of warm waters by the Tsushima and Kuroshio Currents. The variations of the parameter are dominated by the annual course, interannual variations are expressed in its modulation with periods of about 3 and 11 years, unidirectional trends are weak.
Monthly average values of sea surface temperature from January 1998 to August 2020 are analyzed for the region covering the water area of the Far East seas and the northwestern part of the Pacific Ocean. The time function of the first mode, which describes more than 95% of the variance of a parameter under study, has been shown to have significant positive deviations from the average long-term values in January–April 2020 in the southern part of the study area, which covers the traditional feeding grounds of pink salmon. It may have been these abnormally high temperatures that affected the fish survival conditions and obstructed the spawning passage to the Russian Far East shores in the summer of 2020. In spring (May–June), the anomalies in the southern part of the study area became less expressed, but significant positive deviations from the norm appeared in its northern part and near the eastern (including the Karaginsky Bay) and western coasts of Kamchatka. Only very weak uptrends were revealed in time functions of the principal modes, indicating that there are no significant global warming trends in the region. Their envelopes with respect to lower values involve a clear manifestation of an 11-year cycle that is in antiphase with solar activity indices. No regular (for example, cyclical) components are found in variations of summer maxima in the time function of the first mode. In the oscillations of maxima of the time function of the second mode, the main contribution is made by the cyclic component with a period of 22 years.
The aim of the work was to conduct a systematic statistical analysis of the spatial and temporal variability of sea surface temperature (SST) in the waters of the Tatar Strait based on satellite data accumulated in the Sakhalin branch of VNIRO using the TeraScan receiving station for 1998‒2021. It was revealed that in different seasons of the year the SST structure is similar and characterized by the highest values in the southeast and the lowest in the northwest of the strait. An important new result was obtained by expanding of the SST field in terms of the EOF, which is associated with a sharp change in the nature of the time function of the third mode, which occurred in 2013–2014. Such changes can be considered as a climatic shift in the studied area most pronounced in the northwestern part of the strait and near the southwestern coast of Sakhalin Island, where the change was about 1 °C. This circumstance can have a noticeable effect on the state of populations of several species of shrimp and commercial fish.
Size-age structure and spatial distribution of pacific oyster Crassostrea gigas in the Busse Lagoon (Sakhalin Island) in 2010–2020 are analyzed. The oyster colony is in depression. Height of the shells, weight and age of clams have decreased significantly during the decade of observations. The oysters with non-commercial size dominate in the colony.
Purpose. The work is purposed at studying spatio-temporal variability of the resulting long-wave radiation reflecting the ocean heat loss, on the surface of the northwestern Pacific Ocean and the Far Eastern seas based on the ERA5 reanalysis data for 1998-2021. Methods and Results. The ERA5 reanalysis data on the resulting long-wave radiation in the region limited by 42 & DEG;-60 & DEG;N and 135 & DEG;-180 & DEG;E, and including the Far Eastern seas and the northwestern part of the Pacific Ocean constituted the material for the study. The array of monthly averages with a quarter degree spatial resolution was analyzed using the standard statistical methods. Average long-term distributions of long-wave radiation were constructed for each month and by seasons; the amplitudes and phases of the annual and semi-annual harmonics, and the linear trend coefficients were calculated in each spatial cell, also the empirical orthogonal functions decomposition was performed. The highest values of long-wave radiation were observed in winter, primarily in the Sea of Japan and in the area east of Honshu Island. The heat flux from the ocean to the atmosphere reached its significant values in the same areas in autumn, as well as in the coastal strip along the entire continental coast. The most probable reason for such features in the distribution of long-wave radiation is the atmospheric circulation, namely, the steady northwesterly wind (winter monsoon) characteristic of a cold season. In the open ocean, heat loss is less, especially in summer, which is facilitated by dense clouds. Similar results were obtained by the method of empirical orthogonal functions: the values of the first mode spatial distribution decrease from west to east (in absolute value). Conclusions. It was revealed that heat losses in the studied area occur mainly in autumn and winter in its western part - in the Sea of Japan, east of Honshu Island, and especially in a narrow strip along the entire mainland coast; but in winter in the areas north of 48 & DEG;N (the Tatar Strait, the Sea of Okhotsk), they are damped by the ice cover. Unidirectional trends in the changes of long-wave radiation are pronounced relatively weakly, and differ in the same water areas in different seasons of a year.
Using the method of harmonic analysis and EOF decomposition of SST data for the surface of the Sea of Okhotsk and adjacent water areas (42–60° N, 135–160° E, SakhNIRO database and ERA5 reanalysis for 1998–2020), the main features of seasonal variations in thermal conditions were determined. It was revealed that the amplitude of the annual harmonic, which plays a decisive role in the seasonal variations of SST, generally decreases in the direction from west to east throughout the study area, the lowest values are in the zones of quasi- stationary upwellings. The phase increases along the northwest-southeast axis, the total shift is 24–25° (about 3 weeks). In the spatial distribution of the first mode (all values are positive), the water area of the Sea of Japan, the NWPO, and the southwestern part of the Sea of Okhotsk are characterized by high values. Its time function is characterized by a pronounced annual cycle, with a maximum in August–September and a minimum in February–March. The spatial distribution of the second mode has a nodal line running along the Kuril Islands from the Sea of Okhotsk side. The mode values vary along the northwest–southeast axis, with maximum positive values on the northwestern shelf of the Sea of Okhotsk and negative values in the remote part of the NWPO. The time function of the second mode has a positive maximum in July–August and a negative minimum in November–December. This nature of the second mode shows that, against the background of the main SST field described by the first mode, a peculiar seasonal “heat wave” is distinguished, propagating from the northwest to the southeast and passing along this axis in about three weeks, which is an important specific feature of the thermal regime of the study area.
2 Институт морской геологии и геофизики ДВО РАН Южно-Сахалинск, 693022, Россия Для Охотского моря и прилегающих акваторий (области, ограниченной координатами 42-60° с. ш. и 135-160° в. д.) выполнено сравнение среднемесячных рядов температуры поверхности океана (ТПО) по данным спутниковых наблюдений (база СахНИРО) и реанализа ERA5 за 1998-2020 гг.Показано, что зимой и летом в изучаемой области ТПО по данным реанализа выше спутниковой ТПО.Осенью и особенно весной на большей части акватории, напротив, ТПО по спутниковым данным выше, чем по данным реанализа
2 Институт морской геологии и геофизики ДВО РАН Южно-
Long-term average values and anomalies of the duration of the period of positive temperatures and the total water-temperature value have been calculated using satellite data sets on the average daily temperature of the surface water layer for 2010–2020 in sites of traditional fishing for Pacific oyster Crassostrea gigas (Salmon Bay and Busse Lagoon). The dependence of the shell size and total weight of Crassostrea gigas on temperature has been revealed. On the whole, the average values of its height and weight are much lower than the normal value in abnormally warm years and higher than the normal value in abnormally cold years. This may indicate that the oyster, as a temperate-latitude species, is tolerant to cold and moderate temperatures; however, it can hardly develop under conditions of long-term elevated temperatures. The exception is the weight of the mollusk in the Salmon Bay, where its weight is directly correlated with the total water-temperature value.
A series of monthly mean values of the surface temperature in August are created for the Sea of Okhotsk and adjacent waters using 21 years’ worth of satellite measurements (1998–2018). In each spatial cell about 2 × 2 km in size, the amplitudes and phases of harmonics for different periods are determined by the least squares method. Distribution maps with periods that are multiples of a year are constructed for the harmonic amplitudes whose contributions to the interannual variations in the temperature of the surface layer are greatest. Features of the distribution of harmonics with certain periods in the Sea of Okhotsk and adjacent waters are revealed. Harmonics with periods of 6–7 years especially stand out. Their zone of influence covers most of the studied area, due probably to quasi-periodic oscillations of the Tsushima current. From south to north, the main periods change gradually from 6 to 11 years. However, in the northwestern part of the Sea of Okhotsk, the influence of the high-frequency component with a period of about three years also affects. The possibility of forecasting the temperature of the surface layer for the year ahead is shown, taking into account the parameters of a linear trend and the four harmonics with the largest amplitudes.
Институт морской геологии и геофизики ДВО РАН Южно-Сахалинск, 693022, Россия На основе материалов многолетних спутниковых наблюдений приземного атмосферного давления рассчитаны средние многолетние показатели (нормы) за период с 1998 по 2019 г.Также для каждого месяца построены карты пространственных распределений аномалий (отклонений фактического атмосферного давления от рассчитанной нормы).Наиболее значимые аномалии, как по величине, так и по масштабу, наблюдались в январе 2007, 2009 гг.и в июле 2003, 2004 гг.В январе 2009 г. это привело к понижению площади ледового покрова в Охотском море.В июле 2003 г. вторжение арктического воздуха и его длительное пребывание над Охотским морем замедлило прогрев поверхностного слоя воды, а в июле 2004 г. вторжение тихоокеанского воздуха привело к значительным положительным аномалиям температуры поверхности океана (ТПО).Помимо оценки аномалий проведён гармонический анализ сезонных вариаций приземного атмосферного давления.При анализе пространственного распределения амплитуды годовой гармоники выявлена узкая область с низкими значениями, разделяющая зоны с различным характером годовых вариаций над материком (максимумзимой, минимум -летом) и Тихим океаном (противоположная динамика).Вблизи восточного побережья Сахалина имеется точка, в окрестности которой фаза этой составляющей изменятся на 360°, -аналог амфидромии в теории приливов.При этом над материком фаза изменяется слабо, а вдоль границы раздела между областями с различным характером годового хода -очень резко.Амплитуда полугодовой гармоники невелика над материком и возрастает над океаном
Институт морской геологии и геофизики ДВО РАН Южно-
Для Охотского моря и прилегающих к нему акваторий сформированы ряды среднемесячных значений температуры поверхности моря по спутниковым измерениям продолжительностью в 20 лет (1998–2017 гг.). В каждой пространственной ячейке размером около 2 × 2 км методом наименьших квадратов определены коэффициенты линейного тренда. Такие коэффициенты были рассчитаны для каждого месяца отдельно, для среднегодовых значений, а также для средних значений температуры за сезон. Проанализирована связь этих коэффициентов с наблюдаемым в последние двадцать лет снижением ледовитости на акватории Охотского моря. Показано, что температура поверхностного слоя в данном бассейне снижается, наиболее существенно — в его северной и западной частях. Особенно ярко эта тенденция проявляется весной, что может быть обусловлено более существенным выхолаживанием вод вследствие зимней конвекции при уменьшении площади ледяного покрова.
For the Sea of Okhotsk and the adjacent water areas, a series of mean monthly sea surface temperature values were computed from satellite measurements of 20 years (1998–2017). In each space cell, the coefficients of the linear trend are determined by the method of least squares. Such coefficients were calculated for each month separately, for the whole series as a whole, and also for average values of the temperature for the season. The relationship of these coefficients to the observed decrease in ice extent in the water area of the Sea of Okhotsk during the last twenty years has been analyzed. It is shown that the heat content of the surface layer in this basin decreases, most significantly in its northern and western parts. This trend is especially pronounced in the spring, which may be due to a decrease in ice cover and a more significant cooling of the waters due to winter convection.
Ten-day mean sea surface temperature (SST) series have been collected using satellite measurements in 22 coastal regions adjacent to the river mouths of Sakhalin Island from spring to summer (May–July) in 1998–2017. Average long-term dates of the onset of favorable conditions for the release of salmon juveniles from hatcheries (+6–7°C) have been evaluated. Mean square and extreme deviations from these dates have been determined. Synoptic conditions from 2011, under which there were the greatest delays in the release of salmon from the hatcheries, are analyzed.
