Variability In Snow Accumulation Research Articles

Estimating snow water equivalent over long mountain transects using snowmobile-mounted ground-penetrating radar

The water balance in alpine watersheds is dominated by snowmelt, which provides infiltration, recharges aquifers, controls peak runoff, and is responsible for most of the annual water flow downstream. Accurate estimation of snow water equivalent (SWE) is necessary for runoff and flood estimation, but acquiring enough measurements is challenging due to the variability of snow accumulation, ablation, and redistribution at a range of scales in mountainous terrain. We have developed a method for imaging snow stratigraphy and estimating SWE over large distances from a ground-penetrating radar (GPR) system mounted on a snowmobile. We mounted commercial GPR systems (500 and 800 MHz) to the front of the snowmobile to provide maximum mobility and ensure that measurements were taken on pristine snow. Images showed detailed snow stratigraphy down to the ground surface over snow depths up to at least 8 m, enabling the elucidation of snow accumulation and redistribution processes. We estimated snow density (and thus SWE, assuming no liquid water) by measuring radar velocity of the snowpack through migration focusing analysis. Results from the Medicine Bow Mountains of southeast Wyoming showed that estimates of snow density from GPR ([Formula: see text]) were in good agreement with those from coincident snow cores ([Formula: see text]). Using this method, snow thickness, snow density, and SWE can be measured over large areas solely from rapidly acquired common-offset GPR profiles, without the need for common-midpoint acquisition or snow cores.

Regional features of present winter snow accumulation variability in the North Eurasia from data of observations, reanalysis and satellites

The paper presents data on winter snow accumulation on the Russian territory obtained from different sources: ground measurements of snow depth on meteorological stations, water snow equivalent calculated from data of route surveys, reanalysis, and satellite observations. Three large regions were isolated which are distinguished by characters of the snow depth fluctuations and their long-term tendencies. Comparison of the trends calculated from data of reanalysis and satellite measurements demonstrated essential disagreement of them with data of in situ observations.

Between the North Atlantic Oscillation and the Siberian High: A 4000-year snow accumulation history inferred from varved lake sediments in Finland

Clastic-organic varved sediments from the boreal Lake Kalliojärvi, Central Finland, record changes in snow accumulation for more than 4000 years. The varve record was reconstructed using digital image analysis from 4132 varve yr BP to present with 2.2% counting error and is supported by paleomagnetic data. Two laminae are identified in a typical varve structure: (1) the minerogenic lamina, which accumulates during spring as a result of catchment erosion triggered by spring floods and (2) the organic lamina, which is composed of allochthonous and autochthonous organic matter that accumulates during summer, autumn, and winter. The minerogenic influx is related to variations in snow accumulation and follows the different phases of the North Atlantic Oscillation (NAO). Decreased snow accumulation is related to a weakened NAO phase. Thus, the minerogenic influx record provides additional information about NAO variation. The Fe/Mn ratio is related to changes in redox conditions at the lake floor. The oxygen availability in the lake floor depends on the duration of the ice cover during winter. Strengthened Siberian High (SH) causes colder autumn and winter temperatures and therefore leads to extended duration of ice cover. Fe/Mn can be considered as a proxy for SH. The sediment record suggests pronounced, generally positive but strongly fluctuating NAO phase, from ca. 4100 to 3200 varve yr BP. Periods of strengthened SH are observed at 3900–3600, 1900–1500, and 1200–750 varve yr BP. Our study suggests that NAO and SH operate individually, are not clearly linked, and do not entirely block each other.

Snow accumulation variability at altitude of 7010 m a.s.l. in Muztag Ata Mountain in Pamir Plateau during 1958–2002

Summary Precipitation over high mountain is significant for glacier development and river runoff in arid Tarim Basin in the northwest China. However, a coherent perspective of precipitation variability at high-altitude in Tarim Basin has not been presented until now. Here, a 41-m ice core at altitude of 7010 m a.s.l. was drilled and gotten to determine annual snow accumulation rates at Muztag Ata Mountain in the headwater of Tarim River in Pamir Plateau during summer 2003. Using strong seasonally variation of oxygen isotope and β-radioactivity reference layers, the core was dated reliably back to 1958 and resulted in a 45-year record between 1958 and 2002. The mean annual snow accumulation was about 605 mm water equivalent, which is almost 10 times than precipitation in piedmont with elevation below 3000 m a.s.l. The snow accumulation is characterized by high values in 1960s and early 1970s, followed by a drop in the middle 1970s and a recent decreasing trend. Further analysis suggests the upstream zonal flow variation as the major mechanism linking the regional snow accumulation fluctuation to macroscale circulation conditions. During the high snow accumulation years, the westerly winds between 30 and 50°N from the Mediterranean Sea to Pamir Plateau are weakened. The decreased upstream westerly winds generate anomalous cyclonic flows in the Pamir Plateau, which results in an enhanced advection of moisture from the tropics to the vicinity of Muztag Ata Mountain and is thus consistent with enhanced snow accumulation at the core site. During the low snow accumulation years, the above processes are reversed. On the basis of this high-altitude snow accumulation and temperature, a linear regression model is established to simulate annual mass balance in Muztag Ata region. Results reveal that snow accumulation conditions largely determine the annual mass-balance, which has stronger impaction on Tarim River runoff.

Snowpack sensitivity to perturbed climate in a cool mid‐latitude mountain catchment

AbstractThere is great interest in ascertaining the degree of climate change necessary to induce substantial changes in snow accumulation and ablation processes in mountain headwater catchments. Therefore, the response of mountain snow hydrology to changes in air temperature and precipitation was examined by simulating a perturbed climate in Reynolds Mountain East (RME), a headwater catchment with a cool mountain climate in Idaho, USA. The cold regions hydrological model was used to calculate snow accumulation, wind redistribution by blowing snow, interception by forest canopies, sublimation and melt for 25 seasons in RME. The uncalibrated simulations of the highly redistributed snow water equivalent compared well to measurements. Results showed that with concomitant occurrence of warming (5 °C) and precipitation change (±20%) in RME, the peak seasonal snow accumulation decreased by 84–90%, snowmelt decreased 51–79%, rainfall to total precipitation ratio increased from 30% to 78%, and overwinter blowing snow transport and sublimation losses from intercepted snow, the snow surface and blowing snow decreased dramatically. Warming causes an increase in inter‐water year snowcover variability but a decrease in spatial snow accumulation variability. When warming exceeded 1 °C and a precipitation increased by less than 20%, the peak snow accumulation declined dramatically. The results contrast with those from further north along the North American Cordillera in Yukon, Canada, where the impacts of similar warming on alpine snow can be partly compensated for by concomitant increases in precipitation of less than 20%. Copyright © 2015 John Wiley & Sons, Ltd.

Validating the Variability of Snow Accumulation and Melting From GPS-Reflected Signals: Forward Modeling

The variability of snow accumulation and melting is one of the most important interactions of the Earth’s surface with atmosphere through energy transmission and mass balance. In this paper, the effects of snow accumulation and melting together with bare soil and fixed snow depth on the reflected global positioning system (GPS) signals are investigated using GPS antenna gains and multipath signal. The reflected GPS signals are modeled and employed to analyze the interactions of snow accumulation, snow melting, bare soil, and fixed snow depth at BAKE and KUUJ GPS stations in Northern Canada. The results show the clear independency of the snow accumulation and melting variations with bare soil and fixed snow depth, which are validated from GPS-reflected signals as well. The modeled reflected GPS signals indicate the higher frequency of snow accumulation and snow melting than that of bare soil and fixed snow depth, while the estimated power spectral density of the GPS-reflected signals shows the higher signal power of coherence function difference. Furthermore, the GPS observations at BAKE and KUUJ sites confirm such variations with a good agreement during the snow accumulation, melting, bare soil, and fixed snow depth on the ground.

Snowfall and Snowmelt Variability over Himalayan Region in Inter-annual Timescale

The Himalayan mountain system is the source of one of the world's largest supplies of freshwater, as all the major south Asian rivers originate in the Himalayas and their upper catchments are covered with snow and glaciers. There have been no studies describing large-scale pattern of snowmelt over this region. In order to develop a physically based distributed snowmelt-runoff model, a study on the variability of snowfall and snowmelt in the Himalayas is essential. Therefore, for the first time, a study on the variability of snow accumulation and ablation has been undertaken for this region. Remotely sensed snow water equivalent (SWE) from the National Snow and Ice data Centre (NSIDC) and surface temperature data from the Climate Forecast System Reanalysis (CFSR) have been used to study the snowmelt process in the Himalayas. It is seen that, in April, snowmelt mostly occurs in Afghanistan and northern parts of Jammu and Kashmir. Along the Pir Panjal range, snowfall continues in April. Maximum runoff from snowmelt in Kashmir, Himachal and Uttarakhand occurs in the months of June and July. The degree day factor (snowmelt coefficient) indicating snowmelt rate has been computed and it is found that there is large spatial variations in snowmelt rate over the Himalayas due to variations in surface temperatures, accumulated snow amount and elevation. The melt rate ranges from 0.02 to 0.6cm/oC/day in June. Around the Pir Panjal range and the Satluj basin, the melt rate is higher than other places.

The effects of dating uncertainties on net accumulation estimates from firn cores

AbstractThe mean, trend and variability of net snow accumulation in firn cores are often used to validate model output, develop remote-sensing algorithms and quantify ice-sheet surface mass balance. Thus, accurately defining uncertainties associated with these in situ measurements is critical. In this study, we apply statistical simulation methods to quantify the uncertainty in firn-core accumulation data due to the uncertainty in depth–age scales. The methods are applied to a suite of firn cores from central West Antarctica. The results show that uncertainty in depth–age scales can give rise to spurious trends in accumulation that are the same order of magnitude as accumulation trends reported in West Antarctica. The depth–age scale uncertainties also significantly increase the apparent interannual accumulation variability, so these uncertainties must first be accounted for before using firn-core data to assess such processes as small-spatial-scale variability. Better quantification of error in accumulation will improve our ability to meaningfully compare firn-core data across different regions of the ice sheet, and provide appropriate targets for calibration and/or validation of model output and remote-sensing data.

Variability in the annual cycle of the Río Atuel streamflows and its relationship with tropospheric circulation

ABSTRACTClimate‐induced changes in the annual regime of snow‐fed rivers have serious implications for water resource management. In the Central Andes (CA, 28°–36°S) of Argentina–Chile, the snow accumulated in high‐elevation mountains in winter is the dominant component of streamflows during the spring–summer melting season. Although topography introduces complexity in snowpack responses to the annual temperature cycle, streamflow series over a century in length make the CA particularly suitable for identification of long‐term hydrological changes. Principal component (PC) analysis of Río Atuel annual hydrographs from 1906 to 2012 discriminates between precipitation‐ and temperature‐related components associated with variations in snow accumulation (49% of variance) and advances/delays of the streamflow annual peak (21% of variance), respectively. The temporal evolution of PC1 loadings reveals a predominant negative period from 1917 to 1976 and from 1988 to present, suggesting the propensity to undergo long periods with reduced flows. In turn, the PC2 pattern is predominantly positive from 1948 to the present, revealing a tendency to more frequent peak flows in late spring since the mid‐20th century. Above‐average streamflows related to abundant snowfalls in the CA are associated with northward shifts in stormtracks that are remotely induced by above‐average sea surface temperatures in the equatorial Pacific. On the other hand, earlier streamflow peaks in November‐December are concurrent with above‐average temperatures across the Atuel basin induced by enhanced meridional circulation from the Tropics due to the strengthening of the South Atlantic anticyclone. These circulation anomalies are linked to the persistent positive phase of the Southern Annular Mode during the last decades. Additionally, years with reduced streamflows in January, and proportionally larger flow contributions in November‐December, are associated with anomalous air cooling at high levels induced by low pressure centres over the region as part of a quasi‐zonal stationary Rossby wave train that extends from Australia to the South American–South Atlantic sector.

The effect of slope aspect on the response of snowpack to climate warming in the Pyrenees

The aim of this study was to analyse the effect of slope aspect on the response of snowpack to climate warming in the Pyrenees. For this purpose, data available from five automatic weather stations were used to simulate the energy and mass balance of snowpack, assuming different magnitudes of an idealized climate warming (upward shifting of 1, 2 and 3 °C the temperature series). Snow energy and mass balance were simulated using the Cold Regions Hydrological Modelling platform (CRHM). CRHM was used to create a model that enabled correction of the all-wave incoming radiation fluxes from the observation sites for various slope aspects (N, NE, E, SE, S, SW,W,NW and flat areas), which enabled assessment of the differential impact of climate warming on snow processes on mountain slopes. The results showed that slope aspect was responsible for substantial variability in snow accumulation and the duration of the snowpack. Simulated variability markedly increased with warmer temperature conditions. Annual maximum snow accumulation (MSA) and annual snowpack duration (ASD) showed marked sensitivity to a warming of 1 °C. Thus, the sensitivity of the MSA in flat areas ranged from 11 to 17 % per degree C amongst the weather stations, and the ASD ranged from 11 to 20 days per degree C. There was a clear increase in the sensitivity of the snowpack to climate warming on those slopes that received intense solar radiation (S, SE and SW slopes) compared with those slopes where the incident radiation was more limited (N, NE and NW slopes). The sensitivity of the MSA and the ASD increased as the temperature increased, particularly on the most irradiated slopes. Large interannual variability was also observed. Thus, with more snow accumulation and longer duration the sensitivity of the snowpack to temperature decreased, especially on south-facing slopes.

Late-Holocene NAO and oceanic forcing on high-altitude proglacial sedimentation (Lake Bramant, Western French Alps)

Comparison of glacially derived clastic inputs in high altitude proglacial lake Bramant (Western French Alps) with measured North Atlantic Oscillation winter (NAOw) index reveals an inverse correlation between ad 1884 and 1968 at the pluridecadal timescale (20–25 years). This reflects periodical variations in snow accumulation over Lake Bramant catchment area partly influencing the glacier mass balance in the watershed. Further comparisons with reconstructed NAOw index since ad 1500 highlight spatial and temporal variations of the pluridecadal NAOw influence on this alpine climate, especially at the end of the ‘Little Ice Age’. In addition, wavelet analysis of continuous proxies of clastic sedimentation over the last 4150 years indicates significant pluridecadal variability at frequencies compatible with the NAO (30 years), while periods centered at 60–70 years could also be linked to the North Atlantic Ocean–atmosphere internal variability (Atlantic Multidecadal Oscillation (AMO)). The influence of the North Atlantic deep water production on the regional alpine climate is also suggested by a significant 550 yr cycle of clastic inputs since 2800 cal. BP. Coupling between the North Atlantic Ocean and the atmosphere seems therefore to play a fundamental role on glacier mass balance and climate during the late Holocene in the western Alps.

Seasonal small‐scale spatial variability in alpine snowfall and snow accumulation

Key PointsData are based on weather radar and laser scansSpatial variability of snowfall and snow accumulation variabilitySnow accumulation variability is governed by small‐processes close to the ground

Meteorological regimes and accumulation patterns at Utsteinen, Dronning Maud Land, East Antarctica: Analysis of two contrasting years

Since February 2009, an automatic weather station (AWS) has been operating near Utsteinen Nunatak, north of the Sør Rondane Mountains, in Dronning Maud Land at the ascent to the East Antarctic Plateau. This paper gives an assessment of the meteorological conditions, radiative fluxes, and snow accumulation for the first 2 years of operation, 2009 to 2010, analyzed in terms of meteorological regimes. Three major meteorological regimes—cold katabatic, warm synoptic, and transitional synoptic—are identified using cluster analysis based on five parameters derived from the AWS measurements (wind speed, specific humidity, near‐surface temperature inversion, surface pressure, and incoming longwave flux indicative of cloud forcing). For its location, the relatively mild climate at Utsteinen can be explained by the high frequency of synoptic events (observed 41%–48% of the time), and a lack of drainage of cold air from the plateau due to mountain sheltering. During the cold katabatic regime, a strong surface cooling leads to a strong near‐surface temperature inversion buildup. A large difference in accumulation is recorded by the AWS for the first 2 years: 235 mm water equivalent in 2009 and 27 mm water equivalent in 2010. Several large accumulation events during the warm synoptic regime occurring mainly in winter were responsible for the majority of the accumulation in 2009. Mostly, small accumulation events occurred during 2010, frequently followed by snow removal. This interannual variability in snow accumulation at the site is related to the intensity of the local synoptic events as recorded by meteorological regime characteristics.

Snow accumulation variability derived from radar and firn core data along a 600 km transect in Adelie Land, East Antarctic plateau

Abstract. The mass balance of ice sheets is an intensively studied topic in the context of global change and sea-level rise. However – particularly in Antarctica – obtaining mass balance estimates remains difficult due to various logistical problems. In the framework of the TASTE-IDEA (Trans-Antarctic Scientific Traverses Expeditions – Ice Divide of East Antarctica) program, an International Polar Year project, continuous ground penetrating radar (GPR) measurements were carried out during a traverse in Adelie Land (East Antarctica) during the 2008–2009 austral summer between the Italian–French Dome C (DC) polar plateau site and French Dumont D'Urville (DdU) coastal station. The aim of this study was to process and interpret GPR data in terms of snow accumulation, to analyse its spatial and temporal variability and compare it with historical data and modelling. The focus was on the last 300 yr, from the pre-industrial period to recent times. Beta-radioactivity counting and gamma spectrometry were applied to cores at the LGGE laboratory, providing a depth–age calibration for radar measurements. Over the 600 km of usable GPR data, depth and snow accumulation were determined with the help of three distinct layers visible on the radargrams (≈ 1730, 1799 and 1941 AD). Preliminary results reveal a gradual increase in accumulation towards the coast (from ≈ 3 cm w.e. a−1 at Dome C to ≈ 17 cm w.e. a−1 at the end of the transect) and previously undocumented undulating structures between 300 and 600 km from DC. Results agree fairly well with data from previous studies and modelling. Drawing final conclusions on temporal variations is difficult because of the margin of error introduced by density estimation. This study should have various applications, including model validation.

Snow accumulation and its moisture origin over Dome Argus, Antarctica

The spatial and temporal variability of snow accumulation near Dome Argus, Antarctica, is assessed using new snow pit and stake measurement data together with existing snow pit, ice core and automatic weather station records. Snow accumulation rate shows large inter-annual variations, but stable multi-decadal levels over the last seven centuries. Spatial variations in snow accumulation within the space of 50 km of Dome Argus are relatively small, probably thanks to the smooth topography. A comparison of theses accumulation observations with ECMWF reanalyses (ERA-40 and ERA-Interim) suggests ECMWF reanalysis captures the seasonal variations, but underestimates the overall snow accumulation at Dome Argus by ~50 %. The moisture sources for precipitation over Dome Argus are examined by means of a Lagrangian moisture source diagnostic, based on the tracing of specific humidity changes along air parcel trajectories, for the period 2000–2004 using operational ECMWF analysis data. Dome Argus mainly receives moisture from the mid-latitude (46 ± 4°S) South Indian Ocean, with a seasonal latitudinal shift of about 6°. Compared to other central East Antarctic deep ice core sites such as Dome F, Dome C, Vostok, and EPICA Dronning Maud Land, Dome Argus has a more southerly moisture origin, probably due to topographic influences on the moisture transport paths. These results have important implications for the interpretation of future ice cores at Dome Argus.

Snow accumulation following forest disturbance

ABSTRACTMountain pine beetle (MPB) infestation and salvage logging create a post‐disturbance landscape composed of a patchwork of alive, dead, and clearcut forest stands. Subsequent impacts on runoff generation in snowmelt‐dominated hydrological regimes are largely a function of the proportion of landscape covered by each stand type, but basic information on snow accumulation variations between stand types following beetle infestation is lacking. This study examines snow accumulation in the post‐disturbance landscape of northern interior British Columbia, Canada, to quantify the effects of MPB‐related forest cover change. Field measurements collected in a live and a dead coniferous plot during the 2007 and 2008 winters are compared with those collected in a clearcut (canopy‐free control) to identify inter‐plot differences in snow depth, density, and water equivalent. Interannual variability in snow density and water equivalent is significantly affected by interannual variability in meteorological conditions. In high snow years, the dead and alive plots behave similarly due to the ability of large snowfalls to exceed the interception capacity of the canopy. In low‐to‐average snow years, however, distinct differences in snow accumulation between the dead and alive plots are observed. These are largely due to the canopy structure in the dead plot, which differs significantly from that in the healthy plot largely due to defoliation (needle drop) and the loss of fine branches and stems following beetle infestation. Research results provide key process information for modelling studies examining the effects of these changes on runoff generation at the watershed scale. Copyright © 2011 John Wiley & Sons, Ltd.

Synoptic Influences on Snow Accumulation on Glaciers East and West of a Topographic Divide: Southern Alps, New Zealand

Understanding relationships between snow accumulation and synoptic climatology is important for assessing the way in which future climate variability will impact on glacier mass balance. However, few studies have as yet examined these relationships. Variability in snow accumulation on mid-latitude glaciers is strongly influenced by atmospheric circulation, orography, and redistribution of snow by wind. Very little is known about these processes in the New Zealand Southern Alps, where it is assumed that west-facing glaciers receive higher snow totals. However, few measurements are available to test this hypothesis. These processes were investigated over a 21-day period in winter 2008 on glaciers located west (Franz Josef Glacier) and east (Tasman Glacier) of the Main Divide of the Southern Alps. We directly measured snow accumulation and considered how it was affected by synoptic weather regime and location with respect to the Main Divide. Both glaciers received ∼75% of their snowfall during troughing regimes, which are characterized by strong westerly quadrant winds bringing humid air masses from the Tasman Sea over the Southern Alps. The Franz Josef Glacier site received ∼30% more snow than the Tasman Glacier site, but wind deflation meant that by the end of the study period, net snow accumulation was similar at both sites. Blocking synoptic regimes resulted in a reversal of prevailing westerly flow, generating strong downslope winds at Franz Josef Glacier and snow loss.

ドームふじとEPICA DMLの２箇所の深層掘削点を含む東南極ドロンニングモードランドにおける、積雪堆積量の時空間分布

ドームふじとEPICA DMLの２箇所の深層掘削点を含む東南極ドロンニングモードランドにおける、積雪堆積量の時空間分布

Controls on spatial variability in snow accumulation on glaciers in the Southern Alps, New Zealand; as revealed by crevasse stratigraphy

AbstractNet accumulation measurements from two glaciers located on opposite sides of the New Zealand Southern Alps were used to explore processes controlling spatial variability. The degree of variability, as measured by the spatial variogram, differed in each of the three successive years, but the lowest variance occurred on both glaciers in March 2008, after a hot and dry summer. Strong relationships between net accumulation and elevation within the accumulation area were only found on Franz Josef Glacier (FJG), despite this being the primary control used in glacier mass balance modelling. Interaction between wind and topography was found to be important to the distribution of net accumulation on both glaciers. The crevasse stratigraphy method is an ideal way to gain good spatial coverage of net accumulation, and particularly suited to glaciers with high annual precipitation. Copyright © 2010 John Wiley & Sons, Ltd.

Late snowmelt delays plant development and results in lower reproductive success in the High Arctic

In tundra areas where the growing season is short, any delay in the start of summer may have a considerable effect on plant development, growth and reproductive success. Climate models suggest long-term changes in winter precipitation in the Arctic, which may lead to deeper snow cover and a resultant delay in date of snow melt. In this paper, we investigated the role of snow depth and melt out date on the phenological development and reproductive success of vascular plants in Adventdalen, Svalbard (78°10′N, 16°06′E). Effects of natural variations in snow accumulation were demonstrated using two vegetation types (snow depth: meadow 21 cm, heath 32 cm), and fences were used to experimentally increase snow depth by over 1 m. Phenological delay was greatest directly after snowmelt in the earlier phenological phases, and had the largest effect on the early development of those species which normally green-up early (i.e. Dryas, Papaver, Salix, Saxifraga). Compressed growing seasons and length of the reproductive period led to a reduced reproductive success in some of the study species. There were fewer flowers, fewer plots with dispersing seeds, and lower germination rates. This can have consequences for plant establishment and community composition in the long-term.