Traditional precipitation skill scores are affected by the well-known“double penalty”problem caused by the slight spatial or temporal mismatches between forecasts and observations. The fuzzy (neighborhood) method has been proposed for deterministic simulations and shown some ability to solve this problem. The increasing resolution of ensemble forecasts of precipitation means that they now have similar problems as deterministic forecasts. We developed an ensemble precipitation verification skill score, i.e., the Spatial Continuous Ranked Probability Score (SCRPS), and used it to extend spatial verification from deterministic into ensemble forecasts. The SCRPS is a spatial technique based on the Continuous Ranked Probability Score (CRPS) and the fuzzy method. A fast binomial random variation generator was used to obtain random indexes based on the climatological mean observed frequency, which were then used in the reference score to calculate the skill score of the SCRPS. The verification results obtained using daily forecast products from the ECMWF ensemble forecasts and quantitative precipitation estimation products from the OPERA datasets during June-August 2018 shows that the spatial score is not affected by the number of ensemble forecast members and that a consistent assessment can be obtained. The score can reflect the performance of ensemble forecasts in modeling precipitation and thus can be widely used. 相似文献
By using the hourly data from surface meteorological stations in China, the 3-hour precipitation data from
CRA-Interim (Chinese Reanalysis-Interim), ERA5 (ECMWF Reanalysis 5) and JRA-55 (Japanese Reanalysis-55) are
compared, both on the spatial-temporal distributions and on bias with observation precipitation in China. The results
show that: (1) The three sets of reanalysis datasets can all reflect the basic spatial distribution characteristics of annual
average precipitation in China. The simulation of topographic forced precipitation in complex terrain by CRA-interim is
more detailed, while CRA-interim has larger negative bias in central and East China, and larger positive bias in
southwest China. (2) In terms of seasonal precipitation, the three sets of reanalysis datasets overestimate the precipitation
in the heavy rainfall zone of spring and summer, especially in southwest China. CRA interim’s location of the rain belt
in the First Rainy Season in South China is west by south, the summer precipitation has positive bias in southwest and
South China. (3) All of the reanalysis datasets can basically reflect the distribution difference of inter-annual variation of
drought and flood, but the overall the CRA-Interim generally shows negative bias, while the ERA5 and JRA-55 exhibit
positive bias. (4) For the diurnal variation of precipitation in summer, all the reanalysis datasets perform better in
simulating the daytime precipitation than in the night, and bias of CRA-interim is less in southeast and northeast than
elsewhere. (5) ERA5 generally performs the best on the evaluation of quantitative precipitation forecast, the JRA-55 is
the next, followed by the CRA-Interim. CRA-Interim has higher missing rate and lower threat score for heavy rains;
however, at the level of downpour, the CRA-Interim performs slightly better. 相似文献
We analyzed the spatial local accuracy of land cover (LC) datasets for the Qiangtang Plateau, High Asia, incorporating 923 field sampling points and seven LC compilations including the International Geosphere Biosphere Programme Data and Information System (IGBPDIS), Global Land cover mapping at 30 m resolution (GlobeLand30), MODIS Land Cover Type product (MCD12Q1), Climate Change Initiative Land Cover (CCI-LC), Global Land Cover 2000 (GLC2000), University of Maryland (UMD), and GlobCover 2009 (Glob-Cover). We initially compared resultant similarities and differences in both area and spatial patterns and analyzed inherent relationships with data sources. We then applied a geographically weighted regression (GWR) approach to predict local accuracy variation. The results of this study reveal that distinct differences, even inverse time series trends, in LC data between CCI-LC and MCD12Q1 were present between 2001 and 2015, with the exception of category areal discordance between the seven datasets. We also show a series of evident discrepancies amongst the LC datasets sampled here in terms of spatial patterns, that is, high spatial congruence is mainly seen in the homogeneous southeastern region of the study area while a low degree of spatial congruence is widely distributed across heterogeneous northwestern and northeastern regions. The overall combined spatial accuracy of the seven LC datasets considered here is less than 70%, and the GlobeLand30 and CCI-LC datasets exhibit higher local accuracy than their counterparts, yielding maximum overall accuracy (OA) values of 77.39% and 61.43%, respectively. Finally, 5.63% of this area is characterized by both high assessment and accuracy (HH) values, mainly located in central and eastern regions of the Qiangtang Plateau, while most low accuracy regions are found in northern, northeastern, and western regions.
三江源地区是我国重要生态安全屏障,冻土是其高寒生态系统的重要组成部分,冻土的变化深刻影响高寒生态系统固碳及水源涵养.基于英国东英吉利大学(University of East Anglia,UEA)气候研究中心(Climatic Research Unit,CRU)月平均气温再分析资料,利用线性倾向法和滑动平均法并结合... 相似文献
We have observed the time-height variation of the temperature field in the upper troposphere using a Radio Acoustic Sounding System (RASS) which consists of the MU radar and a high-power acoustic transmitter. The fast beam steerability of the MU radar has made it possible to measure temperature profiles in a fairly wide height range in the upper troposphere (5–11 km), even under intense wind conditions. Observations were continued for about 32 hr on 24–26 December, 1986 with a time-height resolution of 30 min and 150 m. During the observation period, the tropospheric jet was so intense that the acoustic wavefronts were severely distorted. Using wind velocity profiles observed by the MU radar we have numerically estimated the propagation of acoustic wavefronts, and further determined favorable pointing directions for the MU radar to receive significant backscattering from refractive index fluctuations produced by the acoustic waves. Conventional radiosonde soundings were carried out every 6 hr, which showed a temperature decrease of 4 K/day in the upper troposphere during the observation period. Temperature profiles taken by RASS agree well with the radiosonde results. 相似文献
The behaviour of the Southern Hemisphere stratosphere has attracted considerable interest, and been compared with the Northern Hemisphere, since the International Geophysical Year (1957–58) when the sudden (explosive or accelerated) springtime warming phenomenon in the Antarctic was first observed. Over the years studies of upper air temperature and wind observations have been made, principally through the spring months when the polar vortex breakdown occurs, utilising both ground-based (rawinsonde, rocket) and more recently, satellite-derived data. Although the radiosonde-derived temperature data are limited both by the number of reporting stations, and the practical difficulty of securing observations much above the 100 hPa level, useful records exist from 1956 or 1957. These have shown that in the 1959 southern spring, the lower stratosphere was relatively colder, and the warming rate through the season was essentially more regular, with little evidence of the marked but short-lived temperature fluctuations usually found. Similar, but not quite such wide-spread conditions occurred again in the 1961 spring. In another study, 30 hPa temperature fields over the Antarctic continent, which could be drawn for the 1967 spring, showed the complexity of the polar vortex breakdown. These features are recalled because extension of the 100 hPa springtime temperature series for the Australian Antarctic station at Casey (66.3°S, 110.5°E) shows that in 1985 and part of 1986, the temperature behaviour there was similar to, but not quite so extreme as that which occurred at Mirny (66.5°S, 93.0°E) in 1959. 相似文献