双月刊

ISSN 1006-9895

CN 11-1768/O4

基于GRAPES-GFS次季节预报的误差诊断和预报能力分析
作者:
作者单位:

中国气象局数值预报中心

作者简介:

通讯作者:

基金项目:

国家重点研究发展计划—地球系统模式大数据 平台与诊断评估系统研制(2017YFA0604502)中国气象局数值预报中心青年基金(400441)


Error diagnosis and Assessment of Sub-seasonal forecast using GRAPES-GFS
Author:
Affiliation:

1.NOAA/NWS/NCEP/EMC, College Park, Maryland, USA;2.Numerical Weather Prediction Center of CMA

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
    摘要:

    基于GRAPES(Global and Regional Assimilation Prediction System)全球预报系统(GRAPES-GFS)的2018年9月-2019年8月的分析场和 35天预报的历史回算数据,对该系统延伸期次季节预报进行误差诊断和预报能力分析。结果表明,该系统可描述2018冬季及2019年夏季2m温度和500hPa位势高度的空间分布特征,但在热力强迫作用显著的高原沙漠地区,尤其是非洲干旱区,GRAPES-GFS的2m温度分析场存在较大的系统偏差。GRAPES-GFS模式的2m温度在超前1- 3周预报的均方根误差近似线型增长,最终趋于稳定。海洋区域2m温度的预报技巧较陆地低,东亚及澳大利亚预报技巧较高。关于500hPa位势高度,在超前1-3周预报时,东亚中低纬度预报技巧明显高于中高纬度地区,热带地区的远低于其它地区,北半球的高于南半球。关于MJO,GRAPES-GFS可描述高层和低层纬向风场的传播和模态特征,可抓住较强对流活动信号的具体位置,但OLR在赤道地区正距平信号偏弱,负距平信号偏强。GRAPES-GFS模式对MJO的ACC有效预报技巧达到11天左右,与一般大气模式预报水平接近。对于选取的两次强MJO事件个例,在超前6天的预报上,GRAPES-GFS可准确地描述2次事件的传播过程,但MJO信号在发展和衰亡阶段强度偏强。

    Abstract:

    Using the analysis and predictions of leading 35 days related to Global and Regional Assimilation Prediction System (GRAPES)-Global Forecast System (GFS) during the period from September 2018 to August 2019, we diagnosed the prediction errors and evaluated the extended forecast capability to improve a numerical weather guidance for the sub-seasonal timescale. Result show that, GRAPES-GFS could capture the spatial distribution characteristics of 2m temperature and 500hPa geopotential height during winter in 2018 and summer in 2019, however there exists large system bias related to 2m temperature analysis in the desert plateau areas which have the thermal forcing effect significantly, especially in arid areas of Africa. Related to 2m temperature, the Root-Mean-Square Errors (RMSE) of leading 1 to 3 weeks predictions approximate to the linear growth. GRAPES-GFS posses the high prediction skill in the East Asia and Austria but have the lower prediction skills in the ocean areas compares with the land areas. Related to 500hPa geopotential height, when leading 1 to 3 weeks predictions, there exist higher prediction skills in low latitude than in high latitudes of East Asia. Also, the prediction skills of the tropics is much lower than other regions and the northern hemisphere is higher than the southern hemisphere. Related to the Madden-Julian Oscillation (MJO), it is found that, GRAPES-GFS can reproduce the propagation characteristic of spatial-temporal variations related to the upper and lower zonal wind and can capture the location of strong convective activity signals. However, the Outgoing Long Wave Radiation (OLR) positive anomaly is much weaker and the negative anomaly is much stronger. GRAPES-GFS have a skillful MJO forecast for 11 lead days when it is useful for ACC and for the selected two strong MJO cases, GRAPES-GFS could describe the MJO propagation process exactly but have a stronger signal during MJO developing and decaying period.

    参考文献
    相似文献
    引证文献
引用本文
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2020-05-21
  • 最后修改日期:2020-08-04
  • 录用日期:2020-12-23
  • 在线发布日期:
  • 出版日期: