General Features of Radar‐Observed Boundary Layer Convergence Lines and Their Associated Convection Over a Sharp Vegetation‐Contrast Area. Issue 5 (4th March 2019)

• Record Type: Journal Article
• Authors: Huang, Yipeng; Meng, Zhiyong; Li, Wanbiao; Bai, Lanqiang; Meng, Xuefeng
• Is Part Of: Geophysical research letters. Volume 46:Issue 5(2019)
• Page Start: 2865
• Page End: 2873
• Publication Date: 2019-03-04
• Subjects: boundary -- vegetation contrast -- convection initiation -- Hetao Irrigation District -- diurnal variation -- convective precipitation; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2018GL081714
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Boundary layer convergence lines (boundaries), an important trigger of convective storms, can be produced by land surface contrasts. This study explored a five‐year summertime radar climatology of boundaries and their associated convection in response to vegetation contrast around the bend of the Yellow River in North China. A total of 323 boundaries were identified with 44% being convection‐associated. The boundaries especially the convective boundaries were more frequent over the arid area than those over the vegetated area and tended to have an orientation parallel to the vegetation contrast line. The boundary activities collocated well with the diurnal variation in surface temperature difference across the vegetation contrast. Compared with the nonconvective boundaries, the convective boundaries formed earlier and moved faster into the inner arid area, obtained maximum length around midday, and then initiated convection. Vegetation contrast might also affect the high‐frequency location and magnitude of boundary‐associated convective precipitation. Plain Language Summary: Boundary layer convergence lines (boundaries) have long been known as an important precursor for convective storms. This study performed a five‐year summertime radar climatology of boundaries and their associated convection in response to vegetation contrast (especially irrigation‐desert contrast) around the bend of the Yellow River in North China. The results showed that the vegetation contrast significantly impacted the boundary characteristics in terms of location, orientation, maximum length, motion, and diurnal cycle, and might potentially impact the high‐frequency location and magnitude of the boundary‐associated convective precipitation as well. Compared with the nonconvective boundaries, the convective boundaries showed higher occurrence frequency in arid area, more apparently orientated along the dominant vegetation contrast line, formed and obtained their maximum length earlier, and moved faster into the inner arid area. These features may aid forecasters in evaluating the potential of a boundary in triggering convection. Key Points: This study conducted a radar climatology of convergence boundaries and their associated convection over a sharp vegetation‐contrast area Vegetation contrast greatly impacted boundary traits, including location, orientation, length, motion, and diurnal cycle Vegetation contrast might modify the occurrence frequency and high‐frequency location of boundary‐associated convective precipitation