Evolution and frontogenesis of an imbalanced flow —the influence of vapor distribution and orographie forcing

• Published in: Advances in atmospheric sciences Vol. 17; no. 2; pp. 256 - 274
• Main Authors: Yunfeng, Wang, Rongsheng, Wu, Yinong, Pan
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.06.2000
• Subjects: Atmosphere; Energy conversion; Evolution; Meteorology; Temperature gradients
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/s00376-000-0008-7

If the initial fields are not in geostrophic balance, the adjustment and evolution will occur in the stratified fluid, and the frontogenesis will occur under suitable conditions. The evolution is studied here with a nonhydrostatic fully compressible meso--scale model (Advanced Regional Prediction System, ARPS). Four cases are designed and compared: (i) control experiment; (ii) with different initial temperature gradient; (iii) with vapor distribution; (iv) with orographie forcing. The results show that: (1) there is an inertial oscillation in the evolution of the imbalanced flow with the frequency of the local Coriolis [function of], and with its amplitude decreasing with time. The stationary balanced state can only be approached as it cannot be reached in the limit duration of time. The energy conversion ratio varies in the range of [0, 1 / 3]; (2) the stronger initial temperature gradient can make the final energy conversion ratio higher, and vice versa; (3) suitable vapor distribution is favorable for the frontogenesis. It will bring forward the time of the frontogenesis, strengthen the intensity of the cold front, and influence the final energy conversion ratio; (4) the orographie forcing has an evidently strengthening effect on the frontogenesis. The strengthening effect on the frontogenesis and the influence on the final energy conversion ratio depend on the relative location of the mountain to the cold front.[PUBLICATION ABSTRACT]