Page 113 - 《高原气象》2025年第3期

3 期 张万里等：基于对流尺度集合样本的高原边坡对流系统和台风系统多元变量背景场误差特征研究 671

Study of Multivariate Background Error Characteristics of Convective

System on Plateau Slope and Typhoon System Based on
Convective-Scale Ensemble Samples

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ZHANG Wanli ， WANG Yuanbing ， LI Rou ， CHEN Yaodeng ，
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MENG Deming ， QIAN Xinyao ， JIN Xili 1
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1
（1. Key Laboratory of Meteorological Disaster of Ministry of Education（KLME）/Joint International Research Laboratory of Climate
and Environment Change（ILCEC）/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters，
Nanjing University of Information Science & Technology， Nanjing 210044， Jiangsu， China；
2. Luoding Meteorological Service， Luoding 527200， Guangdong， China）
Abstract： The effective assimilation of observation data in the slope areas of the Qinghai-Xizang （Tibetan） Pla‐
teau and typhoon systems has a significant impact on the capabilities of weather forecasting in China， with back‐
ground error being a key factor affecting the performance of data assimilation. The purpose of this study is to gain
a deeper understanding of the characteristics of background errors in conventional control variables and hydrome‐
teor control variables within convective systems on the slopes of the Qinghai-Xizang （Tibetan） Plateau and ty‐
phoon systems， so as to develop the data assimilation scheme which is applicable to the convective systems on
the slopes of the Qinghai-Xizang （Tibetan） Plateau and typhoon systems. This study employs the Ensemble
Transform Kalman Filter （ETKF） and the hybrid Ensemble-Variational data assimilation method to update the
ensemble perturbation and the ensemble mean respectively to produce convective-scale ensemble forecast sam‐
ples with 80 ensemble members and 4-kilometers resolution. This study focuses on cases of convective weather
from the northeast slope of the Qinghai-Xizang （Tibetan） Plateau in mid-August 2022 and Typhoon "Meihua"，
the 12th typhoon of 2022. Multivariate background error covariances， including those for multiphase hydromete‐
or and vertical velocity， were computed through physical transformation， vertical transformation， and horizontal
transformation. Analyses of the spatial error characteristics， including the eigenvalues， eigenvectors， and charac‐
teristic length scales were conducted， and the results of the analyses indicate that background errors are more pro‐
nounced in the case of convective system on the slope of the Qinghai-Xizang （Tibetan） Plateau in comparison to
the typhoon system. At the same time， the simulation of hydrometeor variables and vertical velocity is less pre‐
cise in the case of convective system on the slope of the Qinghai-Xizang （Tibetan） Plateau compared to the ty‐
phoon system. In the context of data assimilation for these comparable convective systems， the analysis tends to
be more aligned with observations and less so with the background， this feature highlights the necessity for high-
quality and comprehensive observations in the slope areas of the Qinghai-Xizang （Tibetan） Plateau. In addition，
the atmospheric characteristics and the horizontal scale of hydrometeor variables and vertical velocity in the case
of convective system on the slope of the Qinghai-Xizang （Tibetan） Plateau display smaller and more localized
features compared with those observed in the typhoon system. Moreover， hydrometeor control variables and the
vertical velocity exhibit smaller horizontal scales and more pronounced localized characteristics compared to con‐
ventional control variables， therefore potentially leading to the influence range of observations and information
related to hydrometeor control variables in the slope areas of the Qinghai-Xizang （Tibetan） Plateau relatively lim‐
ited in the context of the subsequent assimilation analysis.
Key words： background error； data assimilation； plateau slope convection； typhoon