Identification of Tropical-Extratropical Interactions and Extreme Precipitation Events in the Middle East based on Potential Vorticity and Moisture Transport
Authorsde Vries, A. J.
Ouwersloot, H. G.
Feldstein, S. B.
El Kenawy, A. M.
KAUST DepartmentBiological and Environmental Sciences and Engineering (BESE) Division
Environmental Science and Engineering Program
Water Desalination and Reuse Research Center (WDRC)
MetadataShow full item record
AbstractExtreme precipitation events in the otherwise arid Middle East can cause flooding with dramatic socioeconomic impacts. Most of these events are associated with tropical-extratropical interactions, whereby a stratospheric potential vorticity (PV) intrusion reaches deep into the subtropics and forces an incursion of high poleward vertically integrated water vapor transport (IVT) into the Middle East. This study presents an object-based identification method for extreme precipitation events based on the combination of these two larger-scale meteorological features. The general motivation for this approach is that precipitation is often poorly simulated in relatively coarse weather and climate models, whereas the synoptic-scale circulation is much better represented. The algorithm is applied to ERA-Interim reanalysis data (1979-2015) and detects 90% (83%) of the 99th (97.5th) percentile of extreme precipitation days in the region of interest. Our results show that stratospheric PV intrusions and IVT structures are intimately connected to extreme precipitation intensity and seasonality. The farther south a stratospheric PV intrusion reaches, the larger the IVT magnitude, and the longer the duration of their combined occurrence, the more extreme the precipitation. Our algorithm detects a large fraction of the climatological rainfall amounts (40-70%), heavy precipitation days (50-80%), and the top 10 extreme precipitation days (60-90%) at many sites in southern Israel and the northern and western parts of Saudi Arabia. This identification method provides a new tool for future work to disentangle teleconnections, assess medium-range predictability and improve understanding of climatic changes of extreme precipitation in the Middle East and elsewhere.
CitationDe Vries AJ, Ouwersloot HG, Feldstein SB, Riemer M, El Kenawy AM, et al. (2017) Identification of Tropical-Extratropical Interactions and Extreme Precipitation Events in the Middle East based on Potential Vorticity and Moisture Transport. Journal of Geophysical Research: Atmospheres. Available: http://dx.doi.org/10.1002/2017jd027587.
SponsorsThe authors wish to thank CRED, ECMWF, NASA, JAXA, and APHRODITE for providing their data sets, which are available under the following links; EM-DAT (http://www.emdat.be/), ERA-Interim (https://www.ecmwf.int/en/research/climate-reanalysis/era-interim), TRMM (https://pmm.nasa.gov/data-access/downloads/trmm), and Aphrodite (http://www.chikyu.ac.jp/precip/english/). We acknowledge the Israeli Atmospheric and Climatic Data Centre (IACDC), supported by the Israeli Ministry of Science, Technology and Space, for providing the Israel Meteorological Service (IMS) daily rainfall records as well as the Ministry of Environment, Water and Agriculture (MEWA) in the Kingdom of Saudi Arabia for providing daily rainfall data. The algorithm is written in the National Center for Atmospheric Research (NCAR) Command Language (NCL) package version 6.3.0, which was also used for the visualization of the data. The algorithm results, as described in section 2.3, are available from the corresponding author upon request. SBF was supported by National Science Foundation grants AGS-1401220 and AGS-1723832. The authors wish to thank Michael Sprenger and Heini Wernli for their helpful suggestions for writing the algorithm for PV intrusions. We greatly appreciate the constructive comments of three anonymous reviewers that helped to improve the quality of the manuscript.