[ACG36-P30] Distinction between precipitation related to a front and that to an interplay of an atmospheric river and a cut-off low
Keywords:atmospheric river, cut off low, GSMaP
Precipitation data are obtained from hourly Global Satellite Mapping of Precipitation (GSMaP) data (0.1 degree grid). Atmospheric rivers and COLs are detected using six-hourly JRA55 (1.25 degree grid) precipitable water and potential vorticity on 350 K isentropic surface, respectively. Then, to evaluate the effect of coexistence of AR and COL upon precipitation enhancement, COLs are classified into two categories named as “AR category” and “non-AR category” by the distance between AR and COL. To investigate the sensitivity of the distance, we set criteria of the distance to 4°, 5°, 6°, and 7°. The analyses are conducted over the western North Pacific region (100E-160W, 0-60N), for the period from March 2000 to February 2013.
Comparing precipitation in the AR category with that in the non-AR category, we can find regions where precipitation in the AR category is significantly enhanced at the northwest and to the north of COL. The positional relationship among AR, COL, and the enhanced precipitation region at the northwest of COL, which is very similar to that of the Hiroshima case, is confirmed even if the criterion of the distance between AR and COL is changed. In contrast, as the distance between AR and COL becomes large, the enhanced precipitation regions to the north of COL move away northward. Such difference indicates that there are two separate mechanisms to produce precipitation at the northwest of COL and that to the north of COL. Namely, the enhanced precipitation region at the northwest of COL is associated with the interplay of an AR and a COL, while that to the north of COL is associated only with an AR.
Acknowledgments: This research was supported by the Environment Research and Technology Development Fund (2-1503) of Environmental Restoration and Conservation Agency, the 8th RA of the Japan Aerospace Exploration Agency (JAXA) Precipitation Measuring Mission (PMM) science, and JSPS KAKENHI Grant Number 15H02132.