Climatic Type Characteristics of the Winter Yunnan-Guizhou Quasi-Stationary Front
Online published: 2025-05-20
Based on the topographic characteristics of the Yunnan-Guizhou Plateau,the 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 years(2000-2023),According to this index,the strong quasi-stationary front events are selected,the temperature,humidity and wind structure of the strong quasi-stationary front events were studied, and the characteristics of different types of strong quasi-stationary front events are compared and analyzed. The results show that:(1)the Yunnan-Guizhou Quasi-Stationary Front manifests as a dense band of isentropic lines (θse)in the mid-to-lower troposphere,with 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. (2)Strong Quasi-Stationary Front is characterized by a dense band of isentropic lines(θse)at the junction of Yun‐ nan and Guizhou. Within the frontal zone,the wind exhibits convergence between northeastern and southwestern winds,with high humidity areas located in the central and western parts of Guizhou to the east of the front. Be‐ low 700 hPa,there is a stark contrast between the notably warmer western region and the significantly cooler eastern region. Below 800 hPa,abnormal easterly winds appear in the eastern area and transition into upward motion around 750 hPa,leading to an enhanced upward transport of moisture. This,in turn,promotes an abnormal structure with upper-level moisture and lower-level dryness to the west of the front.(3)Based on the strength of the cold and warm air on either side of the stationary front,strong quasi-stationary front events are classified into two types:the Cold Anomaly in the East(CE,75%)and the Warm Anomaly in the West(WW,13%). On the surface,the frontal position of WW-type events shifts slightly eastward compared to CE-type events. In CE-type events,the stronger cold anomaly extends westward to 104° E and upward to 750 hPa,while in WW-type events,the stronger warm anomaly extends eastward,with the cold anomaly limited to the east of 106°E and contracting downward below 850 hPa. Below 800 hPa,the abnormal easterly winds in CE-type events are stronger and extend higher than those in WW-type events,promoting more moisture to ascend along the terrain and be transported westward. As a result,the center of positive relative humidity anomalies in WW-type events is located further east compared to CE-type events.
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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