The Predictability of Blocking Character in the Northern Hemisphere Using an Ensemble Forecast System
DeVondria D. Reynolds1, Anthony R. Lupo1, *, Andrew D. Jensen2, Patrick S. Market1
Identifiers and Pagination:Year: 2019
First Page: 13
Last Page: 28
Publisher Id: TOASCJ-13-13
Article History:Received Date: 20/05/2019
Revision Received Date: 29/07/2019
Acceptance Date: 07/08/2019
Electronic publication date: 30/09/2019
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Some weather extremes are the result of atmospheric blocking, which can be responsible for the stagnation of weather patterns. These large-scale quasi-stationary mid-latitude flow regimes can result in significant temperature and precipitation anomalies over the regions that the blocking event impacts or in the upstream and downstream regions.
The ability to predict periods of anomalous weather conditions due to atmospheric blocking is a major problem for medium-range forecasting. Analyzing the National Centers for Environmental Prediction (NCEP) Ensemble 500-hPa pressure level heights (240 hrs.) ten-day forecasts, and using the University of Missouri blocking archive to identify blocking events, the forecasted onset, duration, and intensity of model blocking events are compared to observed blocks.
Results and Discussion:
The observed blocking events were identified using the University of Missouri blocking archive. Comparing these differences using four Northern Hemisphere case studies occurring over a one-year period across the Northern Hemisphere has shown the continued need for improvement in the duration and intensity of blocking events. Additionally, a comparison of the block intensity to a diagnostic known as the Integrated Regional Enstrophy (IRE) was performed in order to determine if there is a correlation between IRE and these quantities.
Having a better understanding of block persistence and their associated anomalies can help society prepare for the damage they can cause.