Three case studies were selected for model testing in the first project year. The guiding principles of the case selection are: 1) it should include a heavy precipitation event that occurred in a wet period, 2) recent years, especial when relevant satellite data is available, should be preferred, 3) we seek synergies between the selected events and past or ongoing research of project team members, 4) the focus should be on summer, although a case in later summer or early fall with snowfall could be considered.
A well documented, long-lived mesoscale convective system (MCS) developed over the TP in mid-July 2008. MCSs are important features of convective precipitation over the TP. On July 18, 2008, a mesoscale Tibetan Plateau Vortex (TPV) formed in the western part of the Tibetan Plateau (TP), traveled eastwards, moved off the TP and then traveled north-eastward all the way to the coast of the Yellow Sea (Feng et al., 2014; Curio et al., 2019). When the TPV reached the eastern TP, it triggered an MCS at the eastern edges of the TP and produced a substantial amount of convective precipitation in the Yangtze river basin.
Case study periods: July 14, 2008, 0 UTC - July 24, 2008, 0 UTCReferences:
Curio, J., R. Schiemann, K.I. Hodges, and A.G. Turner, 2019: Climatology of Tibetan Plateau Vortices in Reanalysis Data and a High-Resolution Global Climate Model. J. Climate, 32, 1933-1950, https://doi.org/10.1175/JCLI-D-18-0021.1.
Feng, X., C. Liu, R. Rasmussen, and G. Fan, 2014: A 10-yr Climatology of Tibetan Plateau Vortices with NCEP Climate Forecast System Reanalysis. J. Appl. Meteor. Climatol., 53, 34-46, https://doi.org/10.1175/JAMC-D-13-014.1.
August 2014 was one of the wettest Augusts in recent decades due to active Monsoon precipitation and embedded extreme precipitation episodes. One particularly intense extreme event led to massive flooding and landslides in western Nepal on 14-15 Aug 2014. During the event, a maximum precipitation amount of 528 mm/24 h was observed at Chisapani station (Karki et al., 2018).
Case study periods: July 27, 2014, 0 UTC - September 1, 2014, 0 UTCReferences:
Karki, R., and Coauthors, 2018: WRF-based simulation of an extreme precipitation event over the Central Himalayas: Atmospheric mechanisms and their representation by microphysics parameterization schemes. Atmos Res, 214, 21-35, https://doi.org/10.1016/j.atmosres.2018.07.016.
A heavy snow event was recorded at an ITP station over the TP and this event is studied by two groups of the project team. The event occurred between October 4 and 8, 2018 around the Nam Co station. This was the largest snowfall event in October since recording began at the Nam Co station in 2005. On October 3, 2018, a gust of cold air passed over the group lakes area, causing the daily minimum temperature of the region to drop by about 4.5℃ within 24 hours. As a result, the daily minimum temperature reached the freezing point about one week ahead of previous years. The snowfall to the east of Nam Co was more than 50 cm while it was only 5 cm in the west of Nam Co.
Case study periods: October 4, 2018, 0 UTC - October 9, 2018, 0 UTC
Figure - Common domain setup. The rectangles show an example domain for the Weather Research and Forecasting (WRF) model.
Here you can find a detailed description of the Common Experimental Design for Case Study Experiments.
