Annotation of the results obtained in 2022
In September 2022, ice core drilling was carried out in the Gorshkov crater on the Ushkovsky volcano at an altitude of 3,950 m. The recovered core, 14 m long, was shipped to Moscow in a frozen condition. The cold laboratory of the Institute of Geography of the Russian Academy of Sciences performed stratigraphic description of the core and measured its density. Currently, chemical analyses of the ice core are being carried out. The snow and firn strata in the apex area of the Ushkovsky volcano crater are characterized by very high ice content as a result of freezing of melt water and liquid precipitation at subzero temperatures in the upper part of the glacier. The meteorological conditions during the period of work were characterized by active cyclonic activity related to the aggravation of the Far East branch of the polar front extending along the Aleutian Islands through the Kurils and Primorsky Krai. The aggravation of this section of the high-latitudinal planetary front zone was connected with the formation of a center of anomalously cold arctic air over the mainland Far East in combination with the outflow of marine tropical air over the Pacific Ocean area. As a result, the weather conditions were characterized by extreme instability. The mean temperature over a 10-day period (13-23 September) was -11°C. Maximum mean wind speeds averaged 27 m/s on 20 September. Wind gusts reached 40 m/s. During the period of work to the south-east of the Kamchatka Peninsula and at the drilling site, a frontal jet current was formed, characterized by the highest wind speed in the Northern Hemisphere. The concentrations of major inorganic (Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, Br-, NO2-, NO3-, SO42-) and several organic (acetate and formate) ions were measured in the obtained core using ion chromatography. The main difference of the Ushkovsky volcano core from other previously studied ones is the very low contribution of anthropogenic sources of pollution. The concentrations of such typical fuel combustion markers as sulfate (SO42-) and nitrate (NO3-) are significantly lower (on average 118 ppb for the Kamchatka core vs. 394 ppb for the Caucasian core) compared to the values for the Elbrus core. This allows us to neglect the anthropogenic influence on the chemical composition of the core and, accordingly, to consider mainly the contribution of other factors, such as forests, forest fires, volcanic activity, the ocean, and sea ice. Ammonium (NH4+) and formate can be used as markers of bioproductivity of forests and forest fires. For these compounds, a certain periodicity of concentration fluctuations can be traced. However, the shallow depth of drilling does not allow us to identify the seasonality of these changes and, as a consequence, does not allow us to date the core. Based on the obtained results, the main markers of biomass burning (ammonium and formate), forest bioproductivity (ammonium, formate, acetate), and sea ice spreading (sodium and chloride ions) can be identified. The examination of space images and archival materials showed the expediency of dendrochronological studies in two areas - Esso and Kliuchevskii group (Ushkovskii). Esso - repeated gathering of samples for prolongation of the chronologies constructed in 1970-1990s. It will allow to estimate the stability of the climatic signal, found in these chronologies of the width of the rings of larch and spruce obtained earlier. On the basis of the new samples, optical density chronologies along the altitudinal profile will be constructed for the first time in Kamchatka to reveal the climatic signal, which is usually more clearly expressed in the ring density than in the width. Both locations will be surveyed to assess above-ground/completely woody biomass/bioproductivity dynamics over the past 100-200 years. For the first time, fire chronologies will be obtained in two locations: volcanic and non-volcanic areas. The lakes located in the glacial zone in the Middle Ridge, on the Kronotsky Peninsula, in the Kluchevskaya group of volcanoes and in the area of Shiveluch volcano were examined on the basis of space imagery materials. Given the transport accessibility, it is most expedient to focus on the latter two areas - Shiveluch volcano and the glaciers of the Klyuchevskaya group. A summary of historical and reconstructed explosive eruptions of Kamchatka volcanoes over the past thousand years, whose ash can be buried in the Ushkovsky volcano glacier, was compiled based on the literature and using weekly data from the Kamchatka Volcanic Eruption Response Team. In addition to the main sources, the summary also included major eruptions of the Stubel cone on Ksudach volcano (South Kamchatka), as well as the eruption of Maly Semyachik volcano. For some sites (Shiveluch, Avachinskii, and Malyi Semyachik), in addition to the list of historical eruptions, information on eruptions reconstructed by means of tephrostratigraphic and/or dendrochronological methods was given. The summary includes 206 eruptions, most of which are associated with two sites - Kliuchevskii volcano (66 eruptions from 1697 to 2021) and Bezymyannyi volcano (55 eruptions from 1955 to 2022). These volcanoes are located just over 10 km away from Ushkovsky volcano and may supply the greatest amount of tephra to the ice material. In contrast to Kliuchevskoi volcano, all eruptions of Bezymyannyi volcano are explosive, accompanied by ashfalls and have a high frequency. Twenty-two eruptions of Shiveluch volcano, one of the most active volcanic centers in Kamchatka, located 80 km north of the Ushkovskii Glacier, were included in the summary. The list of historical events includes two catastrophic eruptions in 1854 and 1964. Kizimen volcano (110 km southwest of Ushkovsky Glacier) has not had a high frequency of eruptions in the last thousand years, but ashfalls from its recent eruption in 2010-2013 spread over considerable distances, including towards Ushkovsky Volcano. Based on the information collected on the scale and nature of eruptions of the most active explosive volcanoes in Kamchatka, as well as available data on the direction of ash plumes distribution, the summary highlighted events whose ash could potentially be present in the glacier. The most extensively documented in the literature and open sources are the eruptions of the last 20 years, when satellite monitoring and video surveillance systems recorded the direction, extent, and area of ash plumes. For earlier historical eruptions, information on the spreading of ash plumes is extremely limited, and indirect evidence, such as references to ash plumes in settlements close to Ushkovskii volcano (Klyuchi, Maiskoye, and Kozyrevsk), was considered to highlight potential events. A total of 36 eruptions whose tephra could have been buried in the glacier were highlighted, including 11 events that occurred since the beginning of the current century.

 

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Annotation of the results obtained in 2023
It is shown that glaciers of the northern part of the Midland Ridge have decreased by 125 km2 or 35.6% from 1950 to 2016-2017. A moderate warming in the region (0.3С/10 years on average) and a significant decrease in winter precipitation in the northern and western parts of Kamchatka (up to 10%/10 years) are revealed. Over the period 1950-2020 there was a significant increase in the radiation balance in the warm period of the year, which in the period 1950-2002 was due to a decrease in shortwave radiation reflected from the surface and albedo, and in 2003-2020 to an increase in incoming shortwave radiation due to a decrease in cloud cover. The increase in the incoming shortwave flux and clear weather is associated with an increase in the recurrence of anticyclones in the region, while the decrease in winter precipitation is associated with a decrease in the Western Pacific Circulation Index (weakening of the cyclone over the Sea of Okhotsk in winter). Against the background of the general background warming in the region, the increase in the radiation balance in the warm season contributed to the glaciation degradation, and for the glaciers of the Middle Ridge, in addition to this, the decrease in winter precipitation. Based on the results of numerical experiments with the SNOWPACK model for the periods 2010-2022 and 1990-2022, information on the stratigraphy, temperature dynamics, density and other characteristics of the snow cover was obtained. The SNOWPACK model reproduction of the snow cover dynamics was evaluated in comparison with the data of 18O isotope analysis in the 2022 core. The data on stratigraphy, temperature and density of the snow cover were obtained by numerical experiment for 1986-1997 and compared with the results of drilling in 1996. Verification of the results showed that the SNOWPACK model significantly underestimates the snow temperature, especially in the middle part of the thickness. Measurements of the width and optical density of tree rings were made for three sites on the slopes of Ushkovsky volcano. Ushkovsky. A total of74 samples were measured in terms of annual ring width (RW) and optical density of latewood (dBI). The obtained chronologies by RW and dBI of rings reach durations from 276 to 365 years. The results of dendroclimatic analysis indicate the presence of a clear limiting factor for larch growth - summer air temperature. The strongest correlation was observed for the highest sites. The optical density of wood has not been measured before in Kamchatka. Continuation of this work will allow the construction of the first dBI chronology for this area, which will become the basis for palaeoclimatic reconstruction. To investigate fire dynamics, samples were collected from burned forest plots preliminarily identified from satellite data. Three RW tree-ring chronologies were constructed and combined into one spanning 420 years (1603 to 2023). The analysis of the position of fire scars in tree cores and spiles indicates the presence of strong upland fires in the period from 1955 to 1983. The methodology of identification and dating of fire events in tree spiles and cores in the areas of burned forest, preliminarily identified by analysing space images, was worked out. Based on the analysis of wood cores from 100 trees, the growth and phytomass reserves in the area of Esso settlement were calculated. The obtained series will also be compared with remote sensing data. On the basis of comparison of data on the tephra composition in the ice core from the Ushkovsky volcano with published data. Ushkovsky and published data on the composition of tephra glasses of modern volcanic eruptions in Kamchatka, the belonging of each tephra horizon to a specific source volcano was determined. It is shown that the main source is the Kliuchevskoi volcano, which is the closest to the glacier and the most productive among the volcanoes of Kamchatka. Inorganic carbon concentration values are low and vary from 200 to 550 ppb, which corresponds to background dust transport from nearby open rock areas. Organic carbon concentration values vary from 75 to 16800 ppb, indicating a high influence of forest fires and serving as a marker of forest bioproductivity. According to the data of NH4+ and Ca2+ concentration changes, together with the results of tephra analysis and stable isotope content analysis, the core was dated. The palaeoclimatic data cover no more than 20 years. By comparing the trends of Na+ and Cl- ions and satellite data on sea ice coverage of the water area, it was shown that the contribution of the latter to the palaeoclimatic signal in the 19th century was insignificant. Comparison of the ion ratio in the core with the standard marine and atmospheric precipitation ion ratios for different regions of Kamchatka showed that the main source of most ions in the core is volcanic emissions both directly during eruptions and as a result of background fumarolic activity. The entire core was analysed for trace element content at 15-30 cm resolution by inductively coupled plasma atomic emission (ICP-IES) and inductively coupled plasma mass spectrometry (ICP-MS). The anthropogenic activity markers (Al, Ti, V, Cr, Ni, Co, As, Sr, Pb, Be, Mo, Cd, Sn, Sb, Cs) showed low values (up to 8 ppb). Based on these results, it can be stated that the anthropogenic load on the glacier is minimal and the main contribution is made by natural factors. On the basis of the data obtained on the Coulter Multisizer 4e counter, as well as on the chemical analysis of samples and stereoscopic images, the first estimate of the total microparticle content in the stratum with identification of the sources of input was obtained. The contribution of anthropogenic pollutants was found to be minimal, with natural sources of material input predominating. The δ18O and δ2H values of ice range from -16 to -24‰ and -110.5 to -177.7‰ with mean values of -20.5 and -150.2‰, respectively. Deuterium excess varies with depth from 8.7 to 21.3‰ with a mean value of 13.7‰. Winter horizons are characterised on average by δ18O values from -19 to -24‰ and d-excess values of 12...16‰ In the distribution of ice δ18O and δ2H values, a trend of increasing values from the depth of 10.66 m a.s.l. to the surface is noticeable against the background of a weakly expressed trend of decreasing d-excess values. This indicates an increased role of summer precipitation in the formation of glacial ice. Comparison with the 1998 core showed that by 2022, the total annual amplitude of δ18O values has decreased, and the tendency for an increase in δ18O values noted for the period from 2008 to 2022 is not observed in the 1998 core, at least for long time intervals exceeding 3-5 years. This may be indicative of climatic changes in the Pacific region over the past 20 years related to atmospheric circulation, as manifested by an increase in the proportion of summer precipitation. The fluctuations of the Bilchenok glacier in the Kliuchevskoi group of volcanoes, which had a pulsating character for at least the last 400-500 years, can be traced along the lateral moraines. In the 20th century, a powerful movement of the glacier occurred in 1959/60, when its tongue moved 2 km and descended to a height of 615 m, penetrating into the birch forest. This movement partially overlapped the lateral moraines of two major previous pulsations at the end and beginning of the 20th century. Another major glacier movement can be traced from moraine fragments 4 km up the left side of the valley and apparently dates back to the beginning of the Little Ice Age. Changes in climate and glaciation in the area of the Kliuchevskoi group of volcanoes were influenced by intensive volcanic activity. As shown by tephrochronological studies in recent decades, catastrophic eruptions of the Ushkovsky volcano (PL1 - 11,650 BP and PL2 - 10,200 BP) occurred in the early Holocene with the formation of extensive calderas at its summit and explosions of up to 12 km3 of eruptive material (Ponomareva et al, 2013). These eruptions should have almost completely destroyed the feeding area of the Bilchenok Glacier and complicated its further existence in the process of growth of cinder cones in the enclosed young caldera and their eruptive activity. Obviously, we can definitely speak about the presence of a moraine 4 thousand years old, while the moraine dated to 8 thousand years ago is most likely the remains of degradation of the Upper Pleistocene glaciation.

 

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