Olga N. Bulygina

Multiple Effects of Changes in Arctic Snow Cover

Snow cover plays a major role in the climate, hydrological and ecological systems of the Arctic and other regions through its influence on the surface energy balance (e.g. reflectivity), water balance (e.g. water storage and release), thermal regimes (e.g. insulation), vegetation and trace gas fluxes. Feedbacks to the climate system have global consequences. The livelihoods and well-being of Arctic residents and many services for the wider population depend on snow conditions so changes have important consequences. Already, changing snow conditions, particularly reduced summer soil moisture, winter thaw events and rain-on-snow conditions have negatively affected commercial forestry, reindeer herding, some wild animal populations and vegetation. Reductions in snow cover are also adversely impacting indigenous peoples’ access to traditional foods with negative impacts on human health and well-being. However, there are likely to be some benefits from a changing Arctic snow regime such as more even run-off from melting snow that favours hydropower operations.

State of the Ground: Climatology and Changes during the Past 69 Years over Northern Eurasia for a Rarely Used Measure of Snow Cover and Frozen Land

Abstract Significant climatic changes over northern Eurasia during the twentieth century are revealed in numerous variables including those affecting and characterizing the state of the cryosphere. In addition to commonly used in situ observations of snow cover such as snow depth and snow courses, synoptic archives in the former Soviet Union contain regular daily and semidaily reports about the state of the ground in the area surrounding the station. Information about frozen, dry, wet, ponded, and snow-covered land, and in the case of snow-covered land, about the characteristics of snow cover, is available in these reports. A new Global Synoptic Data Network (GSDN) consisting of 2100 stations within the boundaries of the former Soviet Union created jointly by the National Climatic Data Center (NCDC) and Russian Institute for Hydrometeorological Information (RIHMI) was used to assess the climatology of snow cover, frozen and unfrozen ground reports, and their temporal variability for the period from 1936 t...

Arctic moisture source for Eurasian snow cover variations in autumn

Eurasian fall snow cover changes have been suggested as a driver for changes in the Arctic Oscillation and might provide a link between sea-ice decline in the Arctic during summer and atmospheric circulation in the following winter. However, the mechanism connecting snow cover in Eurasia to sea-ice decline in autumn is still under debate. Our analysis is based on snow observations from 820 Russian land stations, moisture transport using a Lagrangian approach derived from meteorological re-analyses. We show that declining sea-ice in the Barents and Kara Seas (BKS) acts as moisture source for the enhanced Western Siberian snow depth as a result of changed tropospheric moisture transport. Transient disturbances enter the continent from the BKS region related to anomalies in the planetary wave pattern and move southward along the Ural mountains where they merge into the extension of the Mediterranean storm track.

Recent variations of cloudiness over Russia from surface daytime observations

Changes of total and low cloud fraction and the occurrence of different cloud types over Russia were assessed. The analysis was based on visual observations from more than 1600 meteorological stations. Differences between the 2001–10 and 1991–2000 year ranges were evaluated. In general, cloud fraction has tended to increase during recent years. A major increase of total cloud fraction and a decrease of the number of days without clouds are revealed in spring and autumn mostly due to an increase of the occurrence of convective and non-precipitating stratiform clouds. In contrast, the occurrence of nimbostratus clouds has tended to decrease. In general, the ratio between the occurrence of cumulonimbus and nimbostratus clouds has increased for the period 2001–10 relative to 1991–2000. Over particular regions, a decrease of total cloud fraction and an increase of the number of days without clouds are noted.

Snow cover basal ice layer changes over Northern Eurasia since 1966

An analysis is made of changes in basal ice crust layer characteristics from snow cover surveys made at 958 Russian stations since 1966. The analysis revealed that substantial changes have occurred in response to two competing processes: an increase in thaws associated with strong regional warming and an increase in the duration of the basal ice layer presence on the ground, and a shortening of the snowmelt period associated with a decrease in basal ice layer event frequency and severity. The latter appears to be the more significant process over the past 40 years. Our findings support the notion that the entire spring snowmelt process has become shorter in duration and more intense when taking into account a concomitant trend toward increasing snow depths over large regions of Russia. A more intense spring melt period has important consequences for spring flood dynamics and deserves further study.

Climate variations and changes in extreme climate events in Russia

Daily temperature (mean, minimum and maximum) and atmospheric precipitation data from 857 stations are used to analyze variations in the space–time distribution of extreme temperatures and precipitation across Russia during the past six decades. The seasonal numbers of days (N) when daily air temperatures (diurnal temperature range, precipitation) were higher or lower than selected thresholds are used as indices of climatic extremes. Linear trends in N are calculated for each station for the time period of interest. The seasonal numbers of days (for each season) with maximum temperatures higher than the 95th percentile have increased over most of Russia, with minimum temperatures lower than the 5th percentile having decreased. A tendency for the decrease in the number of days with abnormally high diurnal temperature range is observed over most of Russia. In individual regions of Russia, however, a tendency for an increasing number of days with a large diurnal amplitude is found. The largest tendency for increasing number of days with heavy precipitation is observed in winter in Western Siberia and Yakutia.

Climate Changes in Siberia

This chapter provides observational evidence of climatic variations in Siberia for three time scales: during the past 10,000 years, during the past millennium prior to instrumental observations, and for the past 130 years during the period of large-scale meteorological observations. The observational evidence is appended with the global climate model projections for the twenty-first century based on the most probable scenarios of the future dynamics of the major anthropogenic and natural factors responsible for contemporary climatic changes. Historically, climate of Siberia varied broadly. It was both warmer and colder than the present. However, during the past century, it became much warmer; the cold season precipitation north of 55°N increased, but no rainfall increase over most of Siberia has occurred. This led to drier summer conditions and to increased possibility of droughts and fire weather. Projections of the future climate indicate the further temperature increases, more in the cold season and less in the warm season, significant changes in the hydrological cycle in Central and southern Siberia (summer dryness), ecosystems’ shifts, and changes in the permafrost distribution and stability. Observed and projected frequencies of various extreme events have increased recently and are projected to further increase. While in the north of Siberia, contemporary models predict warmer winters at the end of the twenty-first century and paleoreconstructions hint to warmer summers compared to the present warming observed during the period of instrumental observations. These three groups of estimates are broadly consistent with each other.

Icing conditions over Northern Eurasia in changing climate

Icing conditions, particularly in combination with wind, affect greatly the operation of overhead communication and transmission lines causing serious failures, which result in tremendous economic damage. Icing formation is dangerous to agriculture, forestry, high seas fishery, for land and off coast man-made infrastructure. Quantitative icing characteristics such as weight, thickness, and duration are very important for the economy and human wellbeing when their maximum values exceed certain thresholds. Russian meteorological stations perform both visual and instrumental monitoring of icing deposits. Visual monitoring is ocular estimation of the type and intensity of icing and the date of ice appearance and disappearance. Instrumental monitoring is performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. We used observations at 958 Russian stations for the period 1977–2013 to analyze changes in the ice formation frequency at individual meteorological stations and on the territory of quasi-homogeneous climatic regions in Russia. It was found that hoar frosts are observed in most parts of Russia, but icing only occurs in European Russia and the Far East. On the Arctic coast of Russia, this phenomenon can even be observed in summer months. Statistically significant decreasing trends in occurrence of icing and hoar frost events are found over most of Russia. An increasing trend in icing weights (IWs) was found in the Atlantic Arctic region in autumn. Statistically significant large negative trends in IWs were found in the Pacific Arctic in winter and spring.

Development of Information-Computational Infrastructure for Environmental Research in Siberia as a Baseline Component of the Northern Eurasia Earth Science Partnership Initiative (NEESPI) Studies

This chapter provides a brief description of the information resources currently supporting environmental studies of Siberia including key references and points of contact. It describes environmental, hydrological, and meteorological datasets available for Siberia as well as the tools developed to organize and seamlessly deliver these data to the international research community for studying regional environmental and climatic dynamics of the ongoing global changes. Three-hour and daily datasets of major meteorological characteristics measured at the Siberian weather stations and relevant metadata sets are the first tangible resources available to the researchers. However, most of the Siberian territory is sparsely populated and the observational networks that provide regional in situ observations are also sparse. Therefore, other information resources described below are based upon, or include as their integral part, remote sensing and model output data. These resources are (a) land information system for Siberia that includes cartographical materials, data of different inventories and surveys, diverse databases of in situ measurements and remote sensing products, and numerous auxiliary models for assessment of relevant biophysical indicators of Siberian ecosystems; (b) remote sensing Earth observation products and tools for data search, data access, data visualization, and analysis over Siberia; and (c) a suite of online systems to monitor, process, visualize, analyze, and access Earth science remote sensing products and regional climatic and meteorological geospatial datasets, as well as a variety of geospatial data on climate, climate forecast, hydrology, hydrological forecast, environmental remote sensing, socioeconomic information, etc.

NEESPI Science and Data Support Center for Hydrometeorological Information in Obninsk, Russia

Many meteorological data have little distribution or visibility outside of the host country or institution. One of the priorities of NEESPI is to identify these datasets and promote their distribution to address the science goals of the NEESP Initiative. The number of major synoptic stations over Russia and the former USSR varied from ~100 in the last decade of the 19th century to maximum of ~3500 in 1985. At that time, however, precipitation was measured at ~11 000 locations. Presently, in Russia there are ~1800 synoptic stations. RIHMI-WDC has the largest collection of in-situ meteorological data for the Russian territory, which is the main part of Northern Eurasia. However, this information is not used for research purposes directly. Instead, it serves as a baseline source for specialized sub-arrays to address particular tasks. Russian hydrometeorological baseline data sets may be used for creation of specialized data sets for the NEESPI Information Data Base.