Climatic Type Characteristics of the Winter Yunnan-Guizhou Quasi-Stationary Front

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  • 1. Guizhou Institute of Mountain Meteorological Science ResearchGuiyang 550002GuizhouChina
    2. Climate Center of Guizhou ProvinceGuiyang 550002GuizhouChina
    3. Key Laboratory of the Mountain Climate and Resources of Guizhou ProvinceGuiyang 550002GuizhouChina

Online published: 2025-05-20

Abstract

Based on the topographic characteristics of the Yunnan-Guizhou Plateauthe objective standard index of the intensity of the Yunnan-Guizhou quasi-stationary front in winter is defined by using the FNL atmospheric reanalysis data of 24 years2000-2023),According to this indexthe strong quasi-stationary front events are selectedthe temperaturehumidity and wind structure of the strong quasi-stationary front events were studiedand the characteristics of different types of strong quasi-stationary front events are compared and analyzed. The results show that:(1the Yunnan-Guizhou Quasi-Stationary Front manifests as a dense band of isentropic lines θsein the mid-to-lower tropospherewith the frontal zone tilting eastward with increasing altitude and the gradient distributed in a north-south band. Strong quasi-stationary front events occur most frequently in January 39%and February 33%),and their occurrence frequency shows significant interannual variability. 2Strong Quasi-Stationary Front is characterized by a dense band of isentropic linesθseat the junction of Yun‐ nan and Guizhou. Within the frontal zonethe wind exhibits convergence between northeastern and southwestern windswith high humidity areas located in the central and western parts of Guizhou to the east of the front. Be‐ low 700 hPathere is a stark contrast between the notably warmer western region and the significantly cooler eastern region. Below 800 hPaabnormal easterly winds appear in the eastern area and transition into upward motion around 750 hPaleading to an enhanced upward transport of moisture. Thisin turnpromotes an abnormal structure with upper-level moisture and lower-level dryness to the west of the front.3Based on the strength of the cold and warm air on either side of the stationary frontstrong quasi-stationary front events are classified into two typesthe Cold Anomaly in the EastCE75%and the Warm Anomaly in the WestWW13%. On the surfacethe frontal position of WW-type events shifts slightly eastward compared to CE-type events. In CE-type eventsthe stronger cold anomaly extends westward to 104° E and upward to 750 hPawhile in WW-type eventsthe stronger warm anomaly extends eastwardwith the cold anomaly limited to the east of 106°E and contracting downward below 850 hPa. Below 800 hPathe abnormal easterly winds in CE-type events are stronger and extend higher than those in WW-type eventspromoting more moisture to ascend along the terrain and be transported westward. As a resultthe center of positive relative humidity anomalies in WW-type events is located further east compared to CE-type events.

Cite this article

REN Manlin, BAI Hui, YAN Xiaodong, XIA Yang, LI Zhongyan, ZHENG Bei . Climatic Type Characteristics of the Winter Yunnan-Guizhou Quasi-Stationary Front[J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00055

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