Characteristics of atmosphere - sea ice energy exchange in the Central Arctic

Analysis of an interaction between long-term ice cover and atmosphere in different regions of the Arctic Ocean is conducted. For comparison the energy exchange characteristics in the western and eastern periphery of the Beaufort Gyre, the central part of the Arctic Ocean and in the area to the north of the Kara and Barents seas have been analyzed. The results of calculations based on special observations at Russian drifting station "North Pole-4" and its interpretation using a simple thermodynamic model of sea ice were used. As modern in situ data, meteorological observations at drifting stations "North Pole-35" (2007-2008) and "North Pole-39" (2011-2012) were used. Calculations of turbulent heat fluxes in the region of the drift of the American station "SHEBA" were performed. A good agreement between the calculated fluxes based on the historical data and NP-39 data for the summer period is shown. Monthly mean values and standard deviations of meteorological parameters for winter period are presented on the basis of data from drifting stations "North Pole-35" – "North Pole-40" (2007-2013)

Meteorological winter conditions in the Central Arctic according to the drifting stations “North Pole 35-40”

The effect of clouds, wind speed and long-wave radiative balance on the surface and near-surface air temperature in the Arctic during polar night is presented. The most pronounced bimodality in frequency distributions of the cloud fraction corresponding to cloudy and clear-sky situations is found for the stations NP-35 (2007-2008), NP-37 (2009-2010) and NP-38 (2010-2011). A strong impact of the presence or absence of clouds on the air-surface temperature difference is shown. For clear-sky situations nonmonotonic dependency of near-surface air temperature on wind speed is found

Atmospheric forcing validation for modeling the central Arctic

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 34 (2007): L20706, doi:10.1029/2007GL031378.We compare daily data from the National Center for Atmospheric Research and National Centers for Environmental Prediction “Reanalysis 1” project with observational data obtained from the North Pole drifting stations in order to validate the atmospheric forcing data used in coupled ice-ocean models. This analysis is conducted to assess the role of errors associated with model forcing before performing model verifications against observed ocean variables. Our analysis shows an excellent agreement between observed and reanalysis sea level pressures and a relatively good correlation between observed and reanalysis surface winds. The observed temperature is in good agreement with reanalysis data only in winter. Specific air humidity and cloudiness are not reproduced well by reanalysis and are not recommended for model forcing. An example sensitivity study demonstrates that the equilibrium ice thickness obtained using NP forcing is two times thicker than using reanalysis forcing.This research is supported by the National Science Foundation Office of Polar Programs (under Cooperative Agreements Nos. OPP-0002239 and OPP-0327664) with the International Arctic Research Center, University of Alaska Fairbanks, NSF grant OPP- 0424864 and by Russian Foundation for Basic Research, No. 07-05-13576

Многолетняя изменчивость характеристик климата Северной Якутии — экстремумы температуры воздуха

The article continues the series of publications, describing the modern climate of atmospheric surface layer in the Northern Yakutia and, in details, in the area of Tiksi Hydrometeorological observatory. Climatic characteristics of minimal and maximal air temperatures are estimated with data of standard meteorological measurements, executed at 22 marine and continental meteorological stations in 1978–2010 years, and at HMO Tiksi — during 1936–2015 years. These estimates supplement the information of climatic reference books, based on the data executed before 1980 year, and for some meteorological stations — before 1965 year. The basic characteristics of extremes by months, maps of its spatial distribution and conjugation, annual extremes (the largest and smallest values, its distributions by months, and trends), climatic parameters of seasonal amplitude, and estimates of extreme temperatures, possible one time during 5, 10, 50 and 100 years periods are presented. In addition, the synoptic conditions of storms and sharp temperature changes are investigated.Статья продолжает цикл работ по описанию современного климата приземной атмосферы Cеверной Якутии и, более подробно, района Гидрометеорологической обсерватории Тикси. Климатические характеристики минимальной и максимальной температуры воздуха получены по данным стандартных метеорологических измерений с 1978 по 2010 г. на 22 морских и континентальных ГМС, а для ГМО Тикси — по всем доступным данным c 1936 по 2015 г. Приведенные оценки дополняют информацию климатических справочников, основанную на данных, полученных до 1980 г., а на ряде ГМС и до 1965 г. Представлены таблицы основных характеристик экстремумов по месяцам, карты пространственного распределения и сопряженности, годовые экстремумы (наибольшие и наименьшие значения, их распределение по месяцам и тренды), климатические параметры амплитуды годового хода, оценки экстремальных значений температуры, возможных один раз в 5, 10, 25, 50 и 100 лет. Дополнительно исследованы синоптические условия возникновения штормов и резких перепадов температуры

Growth of the fast ice and its influence on the freezing of bottom sediments in the Buor-Khaya Bay coastal zone, Laptev Sea (in Russian)

Results of the ice and hydrological measurements carried out in the winter of 2014/15 in theTiksiGulf(Buor-KhayaBay) are described. These data served a basis for development of a conceptual thermodynamic model of seasonal freezing of the sea water layers and underlying bottom sediments in the sea-shore zone. The model uses two methods of localization of the phase transition zones: a classical (frontal) one is used for water, while another one within the range of temperatures – for the bottom. For real atmospheric conditions, we investigated specific features of the water freezing through in the shallow coastal zone of theLaptev Sea. The quantitative characteristics of the process were obtained. The calculations demonstrated that the distinguishing feature of the process is a stabilization of the ice thickness, taking place due to essential increasing of a salinity of the sea water. As a result of this, a shallow water body does not frozen through down to the bottom at even the very low air temperatures. Cooled salt waters does not allow liquid to be frozen in pores of the bottom ground. Salinization of the under-ice water layer can cause the melting of fast ice in the shallow water with its simultaneous increase away from the coast. Ice formation in water layers and bottom sediments begins at the same time, although it proceeds differently at different depths. Due to salinization of the bottom ground a continuous frozen zone is not formed, and the whole layer of freezing precipitation is a two-phase (partially frozen) area. As a whole, the model estimates of the process parameters including the motions of the phase fronts agree with known data of direct measurements. Despite such conformity, the model data should be considered as only evaluative ones. If a bottom is flat, the horizontal mixing and advection, which are not reproduced by a one-dimensional model in principle, the actual salinity parameters will most likely not reach the calculated values. However, for small values of the tides in theBuor-KhayaBayand insignificant reverse flows of salt, effect of the last ones does not apparently exert significant influence on the intensity of cooling of the under-ice water layer as well as on the ice formation in upper layers of the bottom within such time scales as a season

On Aethalometer measurement uncertainties and an instrument correction factor for the Arctic

Several types of filter-based instruments are used to estimate aerosol light absorption coefficients. Two significant results are presented based on Aethalometer measurements at six Arctic stations from 2012 to 2014. First, an alternative method of post-processing the Aethalometer data is presented, which reduces measurement noise and lowers the detection limit of the instrument more effectively than box-car averaging. The biggest benefit of this approach can be achieved if instrument drift is minimised. Moreover, by using an attenuation threshold criterion for data post-processing, the relative uncertainty from the electronic noise of the instrument is kept constant. This approach results in a time series with a variable collection time (Delta t) but with a constant relative uncertainty with regard to electronic noise in the instrument. An additional advantage of this method is that the detection limit of the instrument will be lowered at small aerosol concentrations at the expense of temporal resolution, whereas there is little to no loss in temporal resolution at high aerosol concentrations (>2.1-6.7Mm(-1) as measured by the Aethalometers). At high aerosol concentrations, minimising the detection limit of the instrument is less critical. Additionally, utilising co-located filter-based absorption photometers, a correction factor is presented for the Arctic that can be used in Aethalometer corrections available in literature. The correction factor of 3.45 was calculated for low-elevation Arctic stations. This correction factor harmonises Aethalometer attenuation coefficients with light absorption coefficients as measured by the co-located light absorption photometers. Using one correction factor for Arctic Aethalometers has the advantage that measurements between stations become more inter-comparable.Peer reviewe

Припайный лёд в прибрежной части пролива Шокальского

Field investigations of coastal fast ice near the research station Ice Base on the «Cape Baranova», carried out in 2013–2014, made possible to reveal a number of characteristics of the sea ice cover formation. It has been shown that during winter and early spring the sea ice thickness, being formed due to intensive snow drift and caused by that flooding of the ice cover just near the coast of the Bolshevik Island, substantially grows at its upper boundary, that is typical for the Antarctic seas. At the same time, similar process of the ice growth at a relatively short distance from the coast shows all features characteristic for the ice cover in the Arctic seas, and that is well reproduced by the conceptual numerical sea ice model. Thus, the region of the Ice Base «Cape Baranova» represents a natural laboratory for studying the processes of the sea ice formation in both, the Arctic and Antarctic seas under condition of the same atmospheric forcing. Transformation of the fast ice structure during the summer time is described. Results of the investigations has demonstrated that despite the radical changes in the structure thicknesses of the fast ice remained almost unchanged due to the ice growth on the bottom boundary of the ice cover until a destruction of it in August.Приведены результаты исследований припайных льдов пролива Шокальского в районе научно‑исследовательского стационара «Ледовая база «Мыс Баранова». Установлена роль снежного покрова в процессах формирования ледяного покрова в зимний период, характерных как для арктических, так и антарктических морей. Описана трансформация структуры льда в летний период. Показано, что, несмотря на радикальное изменение структуры, толщина припайных льдов практически не изменяется вплоть до взлома припая в августе в результате нарастания льда на нижней границе ледяного покрова

Динамика сезонного протаивания мерзлоты в районе научно-исследовательского стационара «Ледовая база “Мыс Баранова”» (о. Большевик, арх. Северная Земля)

The results of permafrost observations in the northern part of theBolshevikIsland(Severnaya Zemlya Archipelago) started in February 2016 at the meteorological site of the research station “Ice Base “CapeBaranov” are presented. Features of two-year measurements of temperature, heat flux and humidity in the soil active layer due to the processes of its seasonal thawing/freezing, including the so-called “zero curtain effect” are described. The review of climatic and landscape characteristics of the research area, as well as the parameterization of thermophysical properties of the three main types of arctic soils (sandy, sandy loamy and clayey) in the frozen and thawed state was performed. Using the stationary model, realizing the Kudryavtsev’s algorithm, the data of atmospheric reanalysis and direct meteorological observations, interannual variability of seasonal thawing depth as well as mean annual temperature of permafrost surface for various soil types on theBolshevikIslandwere obtained. It is shown that the permafrost-climatic changes during last 70 years, despite significant interannual fluctuations, reflecting the variability of atmospheric conditions at the Severnaya Zemlya Archipelago, are consistent with global temperature increase, and taken into account variations in the snow layer thicknesses and vegetation cover are close to the same measured in 2016–2017 years.Представлены результаты первых мерзлотных наблюдений в северной части о. Большевик (арх. Северная Земля), начатых в феврале2016 г. на НИС «Ледовая база “Мыс Баранова”». Описаны особенности температурной структуры и влажности деятельного слоя грунта, обусловленные процессами сезонного протаивания/промерзания, включая так называемый «эффект нулевого занавеса». Выполнена параметризация теплофизических свойств основных типов арктических грунтов в мерзлом и талом состоянии. С помощью стационарной модели, основанной на известном алгоритме Кудрявцева, данных атмосферного реанализа и прямых метеонаблюдений получены оценки многолетней изменчивости глубины сезонного протаивания грунтов о. Большевик. Показано, что мерзлотно-климатические изменения последних 70 лет, несмотря на существенные межгодовые колебания, согласуются с ходом глобального повышения температуры

The long-term and interannual variability of summer fresh water storage over the eastern Siberian shelf: Implication for climatic change

A time series of summer fresh water content anomalies (FWCA) over the Laptev and East Siberian sea shelves was constructed from historical hydrographic records for the period from 1920 to 2005. Results from a multiple regression between FCWA and various atmospheric and oceanic indices show that the fresh water content on the shelves is mainly controlled by atmospheric vorticity on quasi-decadal timescales. When the vorticity of the atmosphere on the shelves is antycyclonic, approximately 500 km3 of fresh water migrates from the eastern Siberian shelf to the Arctic Ocean through the northeastern Laptev Sea. When the vorticity of the atmosphere is cyclonic, this fresh water remains on the southern Laptev and East Siberian sea shelves. This FWCA represents approximately 35% of the total fresh water inflow provided by river discharge and local sea-ice melt, and is about ten times larger than the standard deviation of the Lena River summer long-term mean discharge. However, the large interannual and spatial variability in the fresh water content of the shelves, as well as the spatial coverage of the hydrographic data, makes it difficult to detect the long-term tendency of fresh water storage associated with climate change

РОСТ ПРИПАЯ И ЕГО ВЛИЯНИЕ НА ЗАМЕРЗАНИЕ ВЕРХНЕГО СЛОЯ ДОННЫХ ОТЛОЖЕНИЙ В ПРИБРЕЖНОЙ ЗОНЕ ГУБЫ БУОР-ХАЯ (МОРЕ ЛАПТЕВЫХ)

Results of the ice and hydrological measurements carried out in the winter of 2014/15 in theTiksiGulf(Buor-KhayaBay) are described. These data served a basis for development of a conceptual thermodynamic model of seasonal freezing of the sea water layers and underlying bottom sediments in the sea-shore zone. The model uses two methods of localization of the phase transition zones: a classical (frontal) one is used for water, while another one within the range of temperatures – for the bottom. For real atmospheric conditions, we investigated specific features of the water freezing through in the shallow coastal zone of theLaptev Sea. The quantitative characteristics of the process were obtained. The calculations demonstrated that the distinguishing feature of the process is a stabilization of the ice thickness, taking place due to essential increasing of a salinity of the sea water. As a result of this, a shallow water body does not frozen through down to the bottom at even the very low air temperatures. Cooled salt waters does not allow liquid to be frozen in pores of the bottom ground. Salinization of the under-ice water layer can cause the melting of fast ice in the shallow water with its simultaneous increase away from the coast. Ice formation in water layers and bottom sediments begins at the same time, although it proceeds differently at different depths. Due to salinization of the bottom ground a continuous frozen zone is not formed, and the whole layer of freezing precipitation is a two-phase (partially frozen) area. As a whole, the model estimates of the process parameters including the motions of the phase fronts agree with known data of direct measurements. Despite such conformity, the model data should be considered as only evaluative ones. If a bottom is flat, the horizontal mixing and advection, which are not reproduced by a one-dimensional model in principle, the actual salinity parameters will most likely not reach the calculated values. However, for small values of the tides in theBuor-KhayaBayand insignificant reverse flows of salt, effect of the last ones does not apparently exert significant influence on the intensity of cooling of the under-ice water layer as well as on the ice formation in upper layers of the bottom within such time scales as a season.Представлены и проанализированы данные стандартных ледовых наблюдений зимой 2014/15 г. в бухте Тикси (губа Буор-Хая, южная часть моря Лаптевых). Описаны особенности изменчивости поля температур в припайном льду и подлёдном слое моря. Данные наблюдений дополнены модельными оценками замерзания слоя воды и верхних слоёв донных отложений