Связь между переносом метана в атмосферу и разрушением ледяного покрова Карского моря: спутниковые данные за 2003–2019 гг.

Satellite spectrometers operating on the outgoing long-wave IR (thermal) radiation of the Earth and placed in sunsynchronous polar orbits provide a wealth of information about Arctic methane (CH4) year-round, day and night. Their data are unique for estimating methane emissions from the warming Arctic, both for land and sea. The article analyzes concentrations of methane obtained by the AIRS spectrometer in conjunction with microwave satellite measurements of sea ice concentration. The data were filtered for cases of sufficiently high temperature contrast in the lower atmosphere. The focus is on the Kara Sea during autumn-early winter season between 2003 and January 2019. This sea underwent dramatic decline in the ice cover. This shelf zone is characterized by huge reserves of oil and natural gas (~90% methane), as well as presence of sub-seabed permafrost and methane hydrates. Seasonal cycle of atmospheric methane has a minimum in early summer and a maximum in early winter. During last 16 years both summer and winter concentrations were increasing, but with different rates. Positive summer trends over the Kara Sea and over Atlantic control area were close one to another. In winter the Kara Sea methane was growing faster than over Atlantic. The methane seasonal cycle amplitude tripled from 2003 to 2019. This phenomenon was considered in terms of growing methane flux from the sea. This high trend was induced by a fast decay of the sea ice in this area with ice concentrations dropped from 95 to 20%. If the current Arctic sea cover would decline further and open water area would grow then further increase of methane concentration over the ocean may be foreseen.Проанализированы ИК спутниковые данные о концентрации метана в слое атмосферы 0–4 км над Карским и Баренцевым морями в сравнении с микроволновыми спутниковыми измерениями ледяного покрова Карского моря. За последние 16 лет амплитуда сезонных вариаций метана над северной частью Карского моря выросла в 3 раза, а площадь поверхности того же района, свободная от льда, увеличилась в 4 раза. Сделан вывод о значительной роли ледяного покрова в экранировании потока метана в атмосферу

Ideas and Perspectives: A Strategic Assessment of Methane and Nitrous Oxide Measurements In the Marine Environment

In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics-namely production, consumption, and net emissions-is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climateactive trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment

The relationship between methane transport to the atmosphere and the decay of the Kara Sea ice cover: satellite data for 2003–2019

Satellite spectrometers operating on the outgoing long-wave IR (thermal) radiation of the Earth and placed in sunsynchronous polar orbits provide a wealth of information about Arctic methane (CH4) year-round, day and night. Their data are unique for estimating methane emissions from the warming Arctic, both for land and sea. The article analyzes concentrations of methane obtained by the AIRS spectrometer in conjunction with microwave satellite measurements of sea ice concentration. The data were filtered for cases of sufficiently high temperature contrast in the lower atmosphere. The focus is on the Kara Sea during autumn-early winter season between 2003 and January 2019. This sea underwent dramatic decline in the ice cover. This shelf zone is characterized by huge reserves of oil and natural gas (~90% methane), as well as presence of sub-seabed permafrost and methane hydrates. Seasonal cycle of atmospheric methane has a minimum in early summer and a maximum in early winter. During last 16 years both summer and winter concentrations were increasing, but with different rates. Positive summer trends over the Kara Sea and over Atlantic control area were close one to another. In winter the Kara Sea methane was growing faster than over Atlantic. The methane seasonal cycle amplitude tripled from 2003 to 2019. This phenomenon was considered in terms of growing methane flux from the sea. This high trend was induced by a fast decay of the sea ice in this area with ice concentrations dropped from 95 to 20%. If the current Arctic sea cover would decline further and open water area would grow then further increase of methane concentration over the ocean may be foreseen

Evidences of accelerating the increase in the concentration of methane in the atmosphere after 2014: satellite data for the Arctic

Проанализированы результаты спутникового зондирования с помощью европейского орбитального интерферометра IASI/MetOP-A и алгоритма обработки данных, разработанного в NOAA. Спутниковые измерения для умеренных и высоких широт Северного полушария дают рост скорости концентрации метана от 4–9 ppbv/год (частей на миллиард по объему) в 2010–2013 гг. до 12–17 ppbv/год в 2015–2016 гг. Глобальные оценки на основе приземных измерений NOAA на прибрежных станциях показывают возрастание от ~5–6 ppbv/год в 2007–2013 гг. до 9–12 ppbv/год в последние два года. Спутниковые данные позволяют анализировать концентрацию метана как над сушей, так и над Арктическими морями при отсутствии приповерхностных инверсий температуры. Результаты дистанционных измерений сравниваются с прямыми самолетными измерениями на Аляске в летне-осенний период в ходе эксперимента CARVE (Carbon in Arctic Reservoirs Vulnerability Experiment). Максимальные аномалии метана (по сравнению с районом между Скандинавией и Исландией) наблюдались в ноябре-декабре над морской поверхностью вдоль берегов Норвегии, Новой Земли, Шпицбергена и других районов Арктики. В летний период аномалии над океаном были незначительны. С годами аномалии росли: максимальная скорость отмечена для района к западу от Новой Земли (9,4±3,7) ppb/год. Над Аляской аномалия концентрации метана в летнее время, когда активны микробиологические источники, росла со скоростью (2,6±1,0) ppb/год. Местоположение максимумов аномалии вокруг Шпицбергена соответствует наблюдавшимся выходам метана с морского дна и предсказанным районам диссоциации метаногидратов. Отмеченное в данной работе увеличение скорости возрастания метана в течение последних двух лет не обязательно говорит о долгосрочной тенденции: 2015–2016 гг. характеризуются как период одного из наиболее сильных эффектов Эль-Ниньо

Possible causes of methane release from the East Arctic seas shelf

We analyze data on methane concentration in the water and lower atmosphere over the shelf of the East Siberian Arctic Seas, which were obtained using marine, terrestrial, and satellite observations. Our study is targeted towards attribution of the enhanced concentrations of methane above the latitudinal-mean, which have been detected at selected locations of these seas. We compare two hypothesis, which attribute it to the effect of modern changes of the sub aquatic permafrost, and to geological factors (tectonics, presence of fault zones and paleo river beds in the study region). Our analysis showed that the methane concentration in sea water are directly related to the distance to the nearest fault zone or paleo river bed, where permafrost is absent and bottom sediments are perforated allowing methane to escape from the deep layers containing gas hydrates. This result indicate that the enhanced emission of methane, which was observed at selected locations of the shelf, is not related to the modern climate change. Earlier study, which was based on mathematical modeling, did not find intensive development of taliks as well as other processes that lead to increased gas permeability of the bottom sediments. Taken together, these results reject the hypothesis of methane catastrophe on the East Siberian Arctic Seas shelf over the foreseeable future

Interannual variations of the carbon monoxide tropospheric burden between 30ºN and 90ºN in 1996-2003: ground-based and satellite measurements, estimate of biomass burning emissions

Carbon monoxide total column amounts in the atmosphere were measured in the High Northern Hemisphere (30º-90º N, HNH) between January 1996 and December 2003 using Fourier Transform Infrared high resolution spectrometers installed at the NDSC (Network for Detection of Stratospheric Change) sites. A grating spectrometer of moderate resolution was employed for the same purpose at the Zvenigorod Research Station of the Institute of Atmospheric Physics near Moscow. CO mixing ratios were measured in the air samples obtained at the ground-level stations of the CMDL (Climate Modeling and Diagnostic Laboratory, NOAA) network. Total column CO amounts were measured from space by the Terra/MOPITT instrument between March, 2000, and December, 2003 (Edwards et al., 2004). Anomalies of monthly mean CO densities (related to a quiet period of 2000 - 2001) for different sites in the HNH were in agreement. This fact confirmed a good mixing of CO in the Northern Hemisphere on the montly basis that may be expected from a 1.5-2-month-long CO life-time. The data were integrated over the HNH reservoir (0-10 km in altitude and 30º-90º N in latitude) and the CO burden anomalies (in Tg) were analysed using a box model. Two CO sinks were taken into account: i) internal chemical removal in the reaction between CO and OH, and ii) transport of CO into the southertn part of the Northern hemisphere, where CO concentrations are usually lower. OH concentarations were taken from Spivakovsky et al. (2000). The air exchange through the 30º N boundary of the reservoir was estimated using the GEOS-CHEM model with a real meteorology of 1998 (Yurganov et al., 2004). The interannual variations of the sinks were neglected; a corresponding uncertainty in the retrieved source anomaly was estimated to be 20-30%. Since 1996 four years have been found to experience high CO emission of similar magnitude (1996, 1998, 2002, and 2003). During four years (1997, 1999, 2000, and 2001) the emissions were relatively low. Seasonal patterns of the emissions in active years were similar, maxima occured in July-August. However, in 2003 emissions in June-July were higher than in August. These semi-hemisphere averaged emission rates correlate with Siberian forest fire counts detected at night time by the ATSR radiometer of the ERS-2 satellite (R2 =0.51). The early peak of 2003 may be attributed to forest fires in Baikal region, Siberia. An inclusion of fire counts for other areas (Europe, North America) only worsen the correlation; this implies a decisive role of the Siberian fires for polluting the Northern Hemisphere troposphere (cf., Kasischke et al., 2005). It was estimated that the boreal forest fires during active years emit 30-60 Tg CO per month in July-August and 150-200 Tg annually. These emissions may be compared to industrial and transport pollution in the Northern Hemisphere estimated by Kasischke et al. (2005) as 290 Tg CO annually (i.e., 25 Tg monthly)