Snow Depth Data Research Articles

Extreme-Value Statistics for Snowpack Water Equivalent in the Northeastern United States Using the Cooperative Observer Network

Abstract A procedure is developed to estimate extreme-value statistics for snowpack water equivalent (SWE) using historical snow depth measurements at cooperative observer stations in the northeastern United States. The method specifies “pseudodensities” that allow transformation of the statistical distribution of the deepest snow-packs to the distribution of extreme SWE values at a location. These pseudodensities vary according to characteristics of the local snow climatology, the geographic location, and the values of the snow depth data themselves. The performance of a suite of theoretical probability distributions for representing the resulting distributions of extreme SWE is also investigated, and it is concluded that five-parameter Wakeby distributions provide the best representations for the region overall. The results suggest that previous estimates for extreme SWE values may underestimate the wettest snowpacks at northern and/or higher-elevation locations, but may yield overestimates in warmer po...

Evaluation of SMMR satellite-derived snow depth using ground-based measurements

Abstract Daily snow depth data for 284 first-order hydromet stations located in the former Soviet Union have been made available for climatological analysis by the U.S.S.R. State Committee for Hydrometeorology. The data are compared with the snow depth product derived from Scanning Multichannel Microwave Radiometer (SMMR) passive microwave brightness temperatures for the year 1980. Results suggest some discrepancies between the two data sources. Anomalies are considered to emanate from a variety of sources. These may include: (a) problems comparing a point measurement to one averaged over a pixel area; (b) an algorithm bias given deep snow conditions; (c) geographical influences such as elevation and forest cover; and (d) presence of depth hoar.

A study of the division of global irradiance into direct beam and diffuse irradiance at seven Canadian sites

Canadian hourly global and diffuse irradiation data and associated daily surface meterological data of humidity, temperature and snow depth for the years 1977–1984 are analyzed. These data have been measured at Edmonton, Goose Bay, Montreal, Port Hardy, Resolute, Toronto and Winnipeg. Hourly values of the clearness index k t and diffuse index k d are sorted into bivariate histograms according to their numerical values. Different histograms are established for different ranges of the three variables: solar elevation, atmospheric precipitable water, and snow depth for each station. Properties of the different histograms are compared using standard statistical procedures. It is found that the division of global irradiation into direct beam and diffuse irradiation is correlated with the four variables k t, precipitable water, solar elevation, and snow depth. It is also found that many, but not all, of the differences between data from the same station at different times and between different stations can be attributed to conditions associated with differences in these four variables. The data show evidence that the division of global irradiation into direct and diffuse irradiation can depend upon the properties of the clouds beyond how these clouds are characterized by the four variables.

Design Ground Snow Loads for Ohio

Abstract The weight of snow with a mean recurrence interval of 50 years, called the design ground snow load, is used by engineers and planners to estimate the weight of snow that roofs must be designed to support National maps of ground snow load have small scales, showing little detail at the state level, and present data with apparent inconsistencies. Snow water equivalent data at ten National Weather Service officer in Ohio and adjacent states were examined to obtain a typical density of 0.15 g cm−3 for the snowpacks with the greatest snow loads. After critical review of 1948–90 daily snow-depth data, 50-yr return-period snow depths were determined for 55 site in Ohio. Design ground snow loads were calculated for these sites by applying the density of 0.15 g cm−3 to the 50-yr return-period snow depths. Several differences were noted between these result and previous maps. Minimum design ground snow loads specified in Ohio building codes are 5–10 lb ft−2 greater than reported here for western Ohio and t...

The role of passive microwaves in characterizing snow cover in the Colorado river basin

Snow cover and snow depth data acquired from meteorological stations and SNOTEL sites in the Colorado river basin of the western US were compared and correlated with brightness temperatures observed by passive microwave sensors. The ground data and satellite data were plotted onto 1/4o latitude by 1/4o longitude grids for the month, January through April and for the years 1979–1986. Results show that correlations were higher when sub-basin areas of the Colorado river were used rather than the entire Colorado river basin, because snow conditions in these areas are more likely to be similar. Multiple regression analysis using, in addition to the microwave data, input on surface roughness and elevation, vegetation and air temperature considerably improved the goodness of fit. Maximum and minimum temperatures were used as surrogates for grain size distributions. Multiple regression correlation coefficients for the eight sub-basin areas studied ranged between 0.49 and 0.86 for all years lumped together. When the regressions were run for individual years to reduce internannual variability of snow conditions, the average correlation coefficients ranged from 0.58–0.91 for the eight sub-basin areas. Based on, results from this study it is evident that grain size information is needed for better snow water equivalent determination using microwave radiometric techniques.

ＴＭデータによるダム集水域の積雪深分布の推定

This study refers to a new method to estimate the snow depth in dam basin using Landsat TM data and digital terrain data. Analysis area (433km2, Ouyubari-dam basin) is located in mountain area in Hokkaido, Japan.The correlation analysis between snow depth and TM data was carried out. As a result of this analysis, it became clear that there was a close correlation between snow depth and band-1, 2, 3, 4 data only in the area of the mixed forest. Furthermore, the multiple regression analysis was carried out. In this analysis, the ground truth data of snow depth and S1, S2, B12 data were used. S1 and S2 values can be obtained by HSI transformation of TM data, and B12 value was calculated by ratio process using TM data. As a result of this analysis, the estimation model for measurement of snow depth using TM data was developed.The distribution map of snow dapth in dam basin (analysis area) was made by applying the estimation model developed by this study to Landsat TM data.

Snowdepth model during snowmelt season in the Taki dam basin

An evaluation method of total precipitation (snow and rain) volume in the Taki dam basin from a few meteorological points is discussed. This method is based on comparison of snow depth data at observation points with the snow survey conducted once a year. 1) Evapotranspiration and groundwater balance are evaluated by Thornthwaite method and by simple model respectively. 2) Water balance in the basin is studied in snowmelt season. 3) Taking account of the relationship between snow moisture volume and snow area from NOAA-AVHRR data, snow depth distributions is estimated.

Differences in mass-balance calculations resulting from alternative sampling and estimation techniques on Glacier No. 1, Tien Shan, China

In May of 1990, three research groups from China, the Soviet Union and the United States visited Glacier No. 1 in the Ürümqi river basin, Xinjiang Uygur Autonomous Region, northwestern China, in a cooperative effort to examine differences in mass-balance calculations resulting from sampling and estimation procedures. Three different snow-depth data sets were collected consisting of: (1) high-resolution depth transects covering the glacier, (2) depths taken from the permanent stake network, and (3) an intermediate data set constructed using the stake network and supplementary depth data from locations not covered by the stake network. The glacier was divided into ten elevation zones and the data were registered to a digital elevation model for analysis. Results show that the permanent stake network provides an accurate estimate of total mass balance if certain techniques are used for extrapolation to higher elevations, although estimates of mass balance for particular regions of the glacier are not accurate. Some regions were overestimated while others were underestimated, leading to a good overall estimate. The intermediate-resolution data set provided better within-zone estimates of mass balance, but was less accurate than the stake network for total mass balance.

Differences in mass-balance calculations resulting from alternative sampling and estimation techniques on Glacier No. 1, Tien Shan, China

In May of 1990, three research groups from China, the Soviet Union and the United States visited Glacier No. 1 in the Ürümqi river basin, Xinjiang Uygur Autonomous Region, northwestern China, in a cooperative effort to examine differences in mass-balance calculations resulting from sampling and estimation procedures. Three different snow-depth data sets were collected consisting of: (1) high-resolution depth transects covering the glacier, (2) depths taken from the permanent stake network, and (3) an intermediate data set constructed using the stake network and supplementary depth data from locations not covered by the stake network. The glacier was divided into ten elevation zones and the data were registered to a digital elevation model for analysis. Results show that the permanent stake network provides an accurate estimate of total mass balance if certain techniques are used for extrapolation to higher elevations, although estimates of mass balance for particular regions of the glacier are not accurate. Some regions were overestimated while others were underestimated, leading to a good overall estimate. The intermediate-resolution data set provided better within-zone estimates of mass balance, but was less accurate than the stake network for total mass balance.

年最大積雪強度の統計的性質とその地域特性

For the purpose to enhance the reliability of design snow loads, the snow depth increase intensity in a short term (3 or 7 days) was studied on the basis of the statistical analyses of daily snow depth data on 423 observation points in Japan. The statistical properties and the regional characteristics of the annual maximum increasing intensity of snow depth for 3 or 7 days (AMI-3 or AMI-7) have been investigated by making a comparison with those of the annual maximum snow depth (AMD). By means of the classification of types of the statistical property on a Type I extreme value probability paper, it was interpreted logically that regional differences of statistical characteristics of AMI-3, AMI-7 and AMD are caused by regional differences of snowfall mechanisms. Furthermore, a reduction coefficient for the design snow loads of buildings is proposed. This coefficient may be used only for the design of buildings which premise such treatments to reduce the snow loads on the roofs as highly reliable snow melting apparatuses.

A STUDY OF THE MAXIMUM SNOW DEPTHS IN NIIGATA PREFECTURE

The purpose of this paper is to explain the distinctive features of the maximum snow depths in NIIGATA prefecture. The maximum snow depth data for the 'cold half' years from 1891 to 1987 were collected from the NIIGATA Local Meteorogical Observatory. The number of observatories keeping data is 60.Concluding remarks are as follows :(1) The deepest disturibution of maximum snow depth is determined by the difference in the height of the eastside or southside mountain chains. (Figs.1, 2, 3, 4)(2) The shallowest disturibution of maximum snow depth is closely proportional to the height of each observatory. (Figs.1, 5)(3) The heavy snow's patterns in NIIGATA prefecture are classified into two types : 1945 yr. and 1963yr. (Figs.6, 7, 8, 9)(4) The upper limit of maximum snow depth which is estimated relative to an observatoty's height is shown by the following formula. (The upper limit line is designated N-Line, Fig.10)Hs=200 logH+75Hs : the upper limit of maximum snow depth (cm)H : the height of the observatory (m)However, the maximum snow depths of two observatories, TAKADA and TOCHIOMATA, were over the N-Line.(5) Taking into account the changes in the maximum snow depths after the latter term of the Meiji era, there seems to be two cycles of snowfalls : a cycle where there is a relatively little snowfall followed by a period of heavy snowfall and then repeating. (Fig.11)(6) In the UONUMA area which has a heavy snowfall for NIIGATA prefecture, there are cycles of mild winters from 5-8 years. All mild winters are not the same as in El Nino years, but there is a possibility that a big El Nino brings a mild to average winter (relatively mild snowfall) to the UONUMA area. (Fig. 12)

Snow-load excitation of the Earth's annual wobble

A global, monthly snow depth data set has been generated from weather satellite (Nimbus 7) observations using passive microwave remote-sensing techniques. In this paper we analyzed five years of data, 1980–1984, to compute the snow-load excitation of the annual wobble of the Earth's rotation axis. A uniform sea-level decrease has been assumed in order to conserve water mass. The result shows dominant seasonal cycles. The prograde component of the annual excitation is Ψ+ = (5.0 milliarcsec, −110*) and the retrograde component Ψ− = (5.0 milliarcsec, −31*). These computed values are compared with previous groundwater estimates, as well as the inferred values from ILS and LAGEOS polar motion measurements. The importance of accurate data is stressed and future plans proposed.

Snow load effect on the Earth's rotation and gravitational field, 1979–1985

A global, monthly snow depth data set has been generated from the Nimbus 7 satellite observations using passive microwave remote‐sensing techniques. In this paper we analyze 7 years of data, 1979–1985, to compute the snow load effects on the earth's rotation and low–degree zonal gravitational field. A uniform sea level decrease has been assumed in order to conserve water mass. The resultant time series show dominant seasonal cycles. The annual peak‐to‐peak variation in J2 is found to be 2.3 × 10 −10, that in J3 to be 1.1 × 10−10, and believed to decrease rapidly for higher degrees. The corresponding change in the length of day is 41 μs. The annual wobble excitation is (4.9 marc sec, −109°) for the prograde motion component and (4.8 marc sec, −28°) for the retrograde motion component. The excitation power of the Chandler wobble due to the snow load is estimated to be about 25 dB less than the power needed to maintain the observed Chandler wobble. The superior quality of the satellite data over conventional data acquired by ground observations and modeling is demonstrated. We also discuss the role of atmospheric water and the problems arising from the lack of snow load observations over the Antarctic and Greenland ice sheets.

Automated monitoring of depth of snow on ground

A system for automatically monitoring snow depth on a network basis is described. Snow depth is sensed by an ultrasonic transducer which combines a reference target and a microprocessor to compensate for changes in temperature. Snow depth data are sampled and temporarily stored on a micrologger at the remote site. The micrologger is linked via telephone to a personal computer so that the stored data can be accessed daily.

The Distribution of Snow Depths in Eastern Slope of Middle Part of the Ou Mountains

It is known that the cloudy or snowy weather expands from the Japan Sea side to the Pacific side through the pass in the backbone range of Japan. Visiting all the villages in piedmont district of Miyagi prefecture, leeside of Ou mountains, the authors collected the data of maximum snow depth in their villages by means of hearing from residents. The distribution of the depths thus obtained is shown in Fig. 2.There are discontinuities in the distribution which indicate the boundaries of deep snow areas as is shown in Figs. 3 and 4. It will be summarized that the deep snow areas are not found on the leeside of the pass of the range but are found on the leeside slope of mountain masses with higher altitudes.