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1.
This article documents how Environment and Climate Change Canada’s Adjusted Daily Rainfall and Snowfall (AdjDlyRS) dataset was developed. The adjustments include (i) conversion of ruler measurements of snowfall to its water equivalent using a previously developed snow water equivalent (SWE) ratio map for Canada; (ii) corrections for gauge-related issues including undercatch and evaporation caused by wind effects and gauge-specific wetting loss, as well as for trace precipitation amounts, using previously developed procedures for Canada. Various data flags (e.g., accumulation flags) were also treated. This dataset contains all Canadian stations reporting daily rainfall and snowfall for which we have metadata to implement the adjustments. The length of the data record varies from one station to another, starting as early as 1840. The results show that the original unadjusted total precipitation data in Environment and Climate Change Canada’s digital archive underestimate the total precipitation in northeastern Canada by more than 25% and by about 10–15% in most of southern Canada. Such large underestimates make the original data unsuitable for water availability and/or balance studies or for numerical model validation, among many other applications. The use of the assumed 10:1 SWE ratio for the archived total precipitation data is the primary cause of the underestimate, which is most severe in northeastern Canada. The trace correction adds 5–20% to precipitation values in northern Canada but less than 5% in southern Canada. The gauge-related corrections do not show an organized spatial pattern but add 5–10% to the precipitation at 312 stations. Long runs (≥3 months) of miscoded missing values were also identified and corrected.
The latest version of the AdjDlyRS dataset is available from the Canadian Open Data Portal; currently it is version 2016, which contains 3346 stations and covers the period from station inception to February 2016. This dataset is suitable for producing gridded precipitation datasets, as well as other applications. 相似文献
2.
A second generation adjusted precipitation daily dataset has been prepared for trend analysis in Canada. Daily rainfall and snowfall amounts have been adjusted for 464 stations for known measurement issues such as wind undercatch, evaporation and wetting losses for each type of rain-gauge, snow water equivalent from ruler measurements, trace observations and accumulated amounts from several days. Observations from nearby stations were sometimes combined to create time series that are longer; hence, making them more useful for trend studies. In this new version, daily adjustments are an improvement over the previous version because they are derived from an extended dataset and enhanced metadata knowledge. Datasets were updated to cover recent years, including 2009. The impact of the adjustments on rainfall and snowfall total amounts and trends was examined in detail. As a result of adjustments, total rainfall amounts have increased by 5 to 10% in southern Canada and by more than 20% in the Canadian Arctic, compared to the original observations, while the effect of the adjustments on snowfall were larger and more variable throughout the country. The slope of the rain trend lines decreased as a result of the larger correction applied to the older rain-gauges while the slope of the snow trend lines increased, mainly along the west coast and in the Arctic. Finally, annual and seasonal rainfall and snowfall trends based on the adjusted series were computed for 1950–2009 and 1900–2009. Overall, rainfall has increased across the country while a mix of non-significant increasing and decreasing trends was found during the summer in the Canadian Prairies. Snowfall has increased mainly in the north while a significant decrease was observed in the southwestern part of the country for 1950–2009. 相似文献
3.
Abstract Trends in Canadian temperature and precipitation during the 20th century are analyzed using recently updated and adjusted station data. Six elements, maximum, minimum and mean temperatures along with diurnal temperature range (DTR), precipitation totals and ratio of snowfall to total precipitation are investigated. Anomalies from the 1961–1990 reference period were first obtained at individual stations, and were then used to generate gridded datasets for subsequent trend analyses. Trends were computed for 1900–1998 for southern Canada (south of 60°N), and separately for 1950–1998 for the entire country, due to insufficient data in the high arctic prior to the 1950s. From 1900–1998, the annual mean temperature has increased between 0.5 and 1.5°C in the south. The warming is greater in minimum temperature than in maximum temperature in the first half of the century, resulting in a decrease of DTR. The greatest warming occurred in the west, with statistically significant increases mostly seen during spring and summer periods. Annual precipitation has also increased from 5% to 35% in southern Canada over the same period. In general, the ratio of snowfall to total precipitation has been increasing due mostly to the increase in winter precipitation which generally falls as snow and an increase of ratio in autumn. Negative trends were identified in some southern regions during spring. From 1950–1998, the pattern of temperature change is distinct: warming in the south and west and cooling in the northeast, with similar magnitudes in both maximum and minimum temperatures. This pattern is mostly evident in winter and spring. Across Canada, precipitation has increased by 5% to 35%, with significant negative trends found in southern regions during winter. Overall, the ratio of snowfall to total precipitation has increased, with significant negative trends occurring mostly in southern Canada during spring. Indices of abnormal climate conditions are also examined. These indices were defined as areas of Canada for 1950–1998, or southern Canada for 1900–1998, with temperature or precipitation anomalies above the 66th or below the 34th percentiles in their relevant time series. These confirmed the above findings and showed that climate has been becoming gradually wetter and warmer in southern Canada throughout the entire century, and in all of Canada during the latter half of the century. 相似文献
4.
Abstract Most water balance studies in the High Arctic indicate that the weather stations underestimate annual precipitation, but the magnitude of such error is unknown. Based on up to seven years of field measurements, this study provides a comparison of snowfall at weather stations with the winter snow accumulation in their nearby drainage basins. Snowfall is the major form of precipitation in the polar region for nine months every year. Without vegetation, snowdrift is controlled by the local terrain. By establishing the snow characteristics for different terrain types, total basin snow storage can be obtained by areally weighting the snow cover for various terrain units in the basin. Such a method was successfully employed to compute total winter snowfall in the drainage basins near Resolute, Eureka and Mould Bay. Results show that the basins had 130 to 300per cent more snow than the weather stations recorded. Using revised snowfall values that are reinforced by Koerner's snow core measurements from ice‐caps, it is hoped that a more realistic precipitation map can be provided for the High Arctic. 相似文献
5.
In this paper, a modern techniqne for correction of precipitation measured with a Nipher shielded rain gauge, with the use of the Valdai Control System as an intercomparison reference, is presented. This technique allows obtaining unbiased daily and timed precipitation data not affected by the rain gauge systematic errors. In conjunction with the existing method of the bias correction for precipitation measured with the Tretyakov precipitation gauge, the problem of generation of unbiased precipitation time series, which includes both types of measurements, covers the entire period of measurements, and has any (i.e., daily through yearly) temporal resolution, is solved. The results of correction for nine stations located in different climatic zones of the Russian Federation are shown. The results are summarized and presented in the form of long-term averages. Statistically homogeneous precipitation time series for the period from 1936 to 2000 are obtained. Temporal trends of annual and cold-season precipitation are calculated and analysed, and their statistical significance is estimated. 相似文献
6.
The WMO recommendations on solid precipitation correction, based on generalized results of precipitation gauge intercomparisons performed in 1985–1996, do not take into account systematic errors in precipitation measurements such as wind-induced at high winds and false precipitation blown by wind into the precipitation gauge during strong blizzards at low temperatures, typical of high latitudes. To eliminate these biases in solid precipitation measurements in the Arctic latitudes, special procedures are proposed for three different national methods of precipitation measurement in Russia, the United States (Alaska), and Canada. Differences in the correction methods in these countries are caused by differences in the design of instruments, observation technique, climate, and content of data archives for calculating the measurement errors. Results of application of the proposed procedures for precipitation correction in the Arctic regions of the above-mentioned countries are discussed. The results are compared against the maps of corrected precipitation in the world water budget and snow, ice resources atlases and in the Handbook for Climate of the USSR. 相似文献
7.
为了更好地使用降水观测数据,对引起称重观测和人工观测的差异原因进行分析,选取北京市15个国家级地面观测站2012年11月—2014年1月称重式降水传感器与人工观测降水量业务资料,探讨称重观测与人工观测累积降水量的差异,并细化为对固态降水和液态降水两种降水类型进行相关性研究。结果表明:称重观测与人工观测日降水量相关系数为0.9990, 88.0%的对比次数中, 两者日降水量差值满足业务要求;在出现固态降水时,称重观测较人工观测降水量偏大,在出现液态降水时,称重观测较人工观测降水量偏小;两者在日降水量等级判断差异较小,小量降水时称重观测的能力较优;防风圈可显著提高称重观测固态降水的捕捉率,而称重观测内筒蒸发对夏季降水测量有一定影响。 相似文献
8.
Safavi Hamid R. Sajjadi Sayed Mahdi Raghibi Vahid 《Theoretical and Applied Climatology》2017,130(1-2):635-653
Water resources in snow-dependent regions have undergone significant changes due to climate change. Snow measurements in these regions have revealed alarming declines in snowfall over the past few years. The Zayandeh-Rud River in central Iran chiefly depends on winter falls as snow for supplying water from wet regions in high Zagrous Mountains to the downstream, (semi-)arid, low-lying lands. In this study, the historical records (baseline: 1971–2000) of climate variables (temperature and precipitation) in the wet region were chosen to construct a probabilistic ensemble model using 15 GCMs in order to forecast future trends and changes while the Long Ashton Research Station Weather Generator (LARS-WG) was utilized to project climate variables under two A2 and B1 scenarios to a future period (2015–2044). Since future snow water equivalent (SWE) forecasts by GCMs were not available for the study area, an artificial neural network (ANN) was implemented to build a relationship between climate variables and snow water equivalent for the baseline period to estimate future snowfall amounts. As a last step, homogeneity and trend tests were performed to evaluate the robustness of the data series and changes were examined to detect past and future variations. Results indicate different characteristics of the climate variables at upstream stations. A shift is observed in the type of precipitation from snow to rain as well as in its quantities across the subregions. The key role in these shifts and the subsequent side effects such as water losses is played by temperature.
相似文献9.
R.L. Davis 《大气与海洋》2013,51(2):169-176
Abstract A topoclimatic classification was developed to map the frequency of damaging spring radiation frosts to six deciduous fruit varieties at a scale of 1:25,000. The methodology utilizes night‐time temperatures from climatological stations operated by the Atmospheric Environment Service (aes) ofEnvironment Canada, as well as night‐time temperatures from a temporary network of standard climate stations and mobile temperature surveys. Maps of the deviation of minimum temperature from the local aes climate station, and of spring frost risk for each fruit variety are produced. 相似文献
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11.
A. F. Nerushev M. A. Novitskii O. Yu. Kalinicheva L. K. Kulizhnikova L. I. Milekhin D. E. Chechin 《Russian Meteorology and Hydrology》2013,38(2):61-70
The dynamics of atmospheric characteristics in the zone of the cyclone which provoked the dangerous atmospheric phenomenon, the heavy snowfall over the center of the European part of Russia in April 2012, is studied using the data of surface and satellite measurements. Besides the observational data from the meteorological stations, the results are used of the measurement of meteorological variables at the high-altitude meteorological mast in Obninsk and of surface concentration of minor gas components. Revealed is a number of interesting features associated with the passage of the cyclone cloud system over the observational point: the dramatic air temperature drop throughout the 300-m layer of the atmosphere, the formation of intensive vertical motions, and the significant temporal variability of O3 and NO2 concentration. The intensity and the total amount of precipitation falling during the cyclone passage are determined using the data of optical measurements of SEVIRI, AVHRR, and MODIS instruments of geostationary and polar orbiting satellites. Demonstrated is the satisfactory agreement of the computed precipitation characteristics with the results of observations at the network of meteorological stations. 相似文献
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13.
丹东地区沿海和山区降雪气候特征 总被引：2，自引：0，他引：2
利用丹东地区4个观测站1955—2010年逐年10月至翌年4月逐日降水量、天气现象、雪深等资料,对丹东地区南部沿海和北部山区降雪气候特征进行了分析,结果表明:丹东地区沿海和山区降雪初日、终日及初终日间隔日数、年降雪日数、年降雪量、降水相态、日最大降雪量、日最大积雪深度等平均特征不同。与山区相比,沿海降雪初期较晚,终期较早,初、终日间日数较短,年降雪日数和年降雪量相对较少。在丹东地区1955—2010年降雪时段平均气温升高趋势显著背景下,丹东地区降雪初期推迟、终期提前、初终日间隔日数缩短;降雪日数减少,其中雨夹雪日数所占百分比显著增多;降雪量减少,其中主要是纯雪量减少;日最大降雪量和积雪深度呈减小趋势;沿海和山区变化幅度不同。 相似文献
14.
Changes in Canada's Climate: Trends in Indices Based on Daily Temperature and Precipitation Data 总被引：1，自引：0，他引：1
ABSTRACTTrends in indices based on daily temperature and precipitation are examined for two periods: 1948–2016 for all stations in Canada and 1900–2016 for stations in the south of Canada. These indices, a number of which reflect extreme events, are considered to be impact relevant. The results show changes consistent with warming, with larger trends associated with cold temperatures. The number of summer days (when daily maximum temperature >25°C) has increased at most locations south of 65°N, and the number of hot days (daily maximum temperature >30°C) and hot nights (daily minimum temperature >22°C) have increased at a few stations in the most southerly regions. Very warm temperatures in both summer and winter (represented by the 95th percentile of their daily maximum and minimum temperatures, respectively) have increased across the country, with stronger trends in winter. Warming is more pronounced for cold temperatures. The frost-free season has become longer with fewer frost days, consecutive frost days, and ice days. Very cold temperatures in both winter and summer (represented by the 5th percentile of their daily maximum and minimum temperatures, respectively) have increased substantially across the country, again with stronger trends in the winter. Changes in other temperature indices are consistent with warming. The growing season is now longer, and the number of growing degree-days has increased. The number of heating degree-days has decreased across the country, while the number of cooling degree-days has increased at many stations south of 55°N. The frequency of annual and spring freeze–thaw days shows an increase in the interior provinces and a decrease in the remainder of the country. Changes in precipitation indices are less spatially coherent. An increase in the number of days with rainfall and heavy rainfall is found at several locations in the south. A decrease in the number of days with snowfall and heavy snowfall is observed in the western provinces, while an increase is found in the north. There is no evidence of significant changes in the annual highest 1-day rainfall and 1-day snowfall. The maximum number of consecutive dry days has decreased, mainly in the south. 相似文献
15.
Abstract The changes in normal precipitation amounts from 1931–60 to 1951–80 are examined for stations in Eastern Canada. The area covered comprises the Maritime Provinces and those parts of Ontario and Quebec south of a line approximately 200 km north of Lakes Erie and Ontario and the St Lawrence River. Changes are computed for each of the four seasons and for the entire year. On the whole, precipitation has increased, especially in winter and summer. However, there is considerable variation throughout the area, with precipitation decreasing in some regions. General circulation models that simulate the effect of doubling atmospheric CO2 also show an increase in precipitation. 相似文献
16.
Evidence of climate change within the Adamello Glacier of Italy 总被引：2，自引：2，他引：0
We analyze a daily series of rainfall, snowfall, air temperature, and snow water equivalent at fixed dates from 40 high-altitude stations on the Adamello Glacier area (Italian Alps), for the period 1965–2007. Purposes of the study are (1) to investigate significant variation in time, (2) to evaluate effect of temperature changes on cryospheric water cycle, and (3) to evaluate underlying climate patterns and the most significant variables for climate change studies. We detect the presence of a trend using linear regression, moving window average and Mann Kendall test. Linear dependence of water related variables on temperatures is assessed. We find substantially unchanged atmospheric water input along with increasing temperature and rainfall, decreasing snowfall and snow water equivalent at thaw, and shortening of snow cover extent and duration. We carry out a principal components analysis which highlights patterns of precipitation distribution resulting from local temperature and external forcing. A set of the most representative variables for climate and glacier studies is then assessed. A comparison with three nearby Southern Alpine glacierized areas in Italy and Switzerland shows substantial agreement. In spite of the relative shortness of the series, the results here are of interest and can be used as a benchmark for climate change impact assessment for the Adamello Glacier area and southern Alps. 相似文献
17.
Jinwon Kim 《Climatic change》2005,68(1-2):153-168
The effects of increased atmospheric CO2 on the frequency of extreme hydrologic events in the Western United States (WUS) for the 10-yr period of 2040–2049 are examined using dynamically downscaled regional climate change signals. For assessing the changes in the occurrence of hydrologic extremes, downscaled climate change signals in daily precipitation and runoff that are likely to indicate the occurrence of extreme events are examined. Downscaled climate change signals in the selected indicators suggest that the global warming induced by increased CO2 is likely to increase extreme hydrologic events in the WUS. The indicators for heavy precipitation events show largest increases in the mountainous regions of the northern California Coastal Range and the Sierra Nevada. Increased cold season precipitation and increased rainfall-portion of precipitation at the expense of snowfall in the projected warmer climate result in large increases in high runoff events in the Sierra Nevada river basins that are already prone to cold season flooding in todays climate. The projected changes in the hydrologic characteristics in the WUS are mainly associated with higher freezing levels in the warmer climate and increases in the cold season water vapor influx from the Pacific Ocean. 相似文献
18.
无资料地区雪灾防御参数常采用周边有资料的气象站参数替代,基于气候背景相似的降雪气候区划可以为代表站的选取提供科学依据。本文利用湖北省76个国家气象站1961—2020年的气象观测资料,选取了降雪初终日、雪日数、积雪日数、降雪量、最大积雪深度等12个多维时间序列指标,采用Hilbert-Schmidt Independence Criterion（HSIC）核函数的有偏估计公式计算12个指标的整体相似性,对湖北省降雪气候进行了聚类分析。结果表明：湖北省降雪气候可以划分为东南部、中部、西北部和西南部4个气候分区,分区的地带性分布特征与湖北省强降雪天气由北方冷空气南下产生的气候背景一致;初雪日从西北部向中部、西南部、东南部降雪区推迟,终雪日则正好相反,西北部的降雪日数和积雪日数最多;东南部代表站为黄石站,中部代表站有麻城、武汉、钟祥,西南部代表站有咸丰、巴东,西北部代表站郧西、老河口。HSIC核函数能很好处理较大年际波动的指标序列集之间的相似性,其聚类方法对湖北省降雪的气候区划较为合理,区划结果为湖北省精细化雪灾防御提供了技术依据。 相似文献
19.
基于天山山区1961-2013年60个气象站点实测气温、降水、相对湿度、日照时数和积雪深度等气候资料,结合时间序列分析、空间分析以及通径分析等方法,全面精确地获取了天山山区气候变化特征以及气候变化对积雪的通径影响。结果表明：天山山区气候变化显著,主要表现为整体增暖、局部变湿与黯化;气候变暖导致天山山区固态降水（降雪）保证率明显降低,尤其是低海拔区域。各气象要素对积雪不仅存在直接的单因素影响而且各气象要素之间还存在间接的相互交叉、相互联结的多因素影响。单因素影响通径分别为气温、降水和日照时数对积雪深度的3条直接影响通径;多因素影响通径分别为气温、降水和日照时数通过相互之间的内在关系对积雪深度产生的6条间接影响通径。最终结果表明气温是积雪变化的主要影响因素,其影响效应远远大于降水和日照时数的影响。 相似文献
20.
Abstract The precipitation chemistry stations operating in the Atlantic Provinces during the period 1980–1982 were assessed by comparing their siting characteristics and sampling procedures with the criteria recommended by the Canadian Federal‐Provincial Research and Monitoring Coordinating Committee (RMCC). The data collected at these stations were also evaluated according to standards recommended by the Unified Deposition Data Base Committee. Only one quarter of the 32 stations satisfied all of these criteria. In addition, there is evidence to suggest that some of the laboratories experienced problems analysing for nitrate or pH. Therefore, producing a coherent region‐wide data set for the major ions in precipitation was not feasible. However, the qualifying measurements were adequate to indicate an excess sulphate deposition of slightly less than 20 kg ha?1 a?1 to most of the region, with less than 10 kg ha?1 a?1 to Labrador. Although this analysis was restricted to the monitoring in Atlantic Canada, the results are of broader relevance in illustrating the potential problems inherent in merging data from several networks. 相似文献