Articles | Volume 10, issue 12
Atmos. Meas. Tech., 10, 4727–4745, 2017

Special issue: Observing Atmosphere and Climate with Occultation Techniques...

Atmos. Meas. Tech., 10, 4727–4745, 2017

Research article 05 Dec 2017

Research article | 05 Dec 2017

A global perspective on atmospheric blocking using GPS radio occultation – one decade of observations

Lukas Brunner1,2 and Andrea K. Steiner1,2,3 Lukas Brunner and Andrea K. Steiner
  • 1Wegener Center for Climate and Global Change (WEGC), University of Graz, Graz, Austria
  • 2FWF-DK Climate Change, University of Graz, Graz, Austria
  • 3Institute for Geophysics, Astrophysics, and Meteorology, Institute of Physics, University of Graz, Graz, Austria

Abstract. Atmospheric blocking represents a weather pattern where a stationary high-pressure system weakens or reverses the climatological westerly flow at mid-latitudes for up to several weeks. It is closely connected to strong anomalies in key atmospheric variables such as geopotential height, temperature, and humidity. Here we provide, for the first time, a comprehensive, global perspective on atmospheric blocking and related impacts by using an observation-based data set from Global Positioning System (GPS) radio occultation (RO) from 2006 to 2016. The main blocking regions in both hemispheres and seasonal variations are found to be represented well in RO data. The effect of blocking on vertically resolved temperature and humidity anomalies in the troposphere and lower stratosphere is investigated for blocking regions in the Northern and Southern hemispheres, respectively. We find a statistically significant correlation of blocking with positive temperature anomalies, exceeding 3 K in the troposphere, and a reversal above the tropopause with negative temperature anomalies below −3 K in the lower stratosphere. Specific humidity is positively correlated with temperature throughout the troposphere with larger anomalies revealed in the Southern Hemisphere. At the eastern and equatorward side of the investigated blocking regions, a band of tropospheric cold anomalies reveals advection of cold air by anticyclonic motion around blocking highs, which is less distinct in the Southern Hemisphere due to stronger zonal flow. We find GPS RO to be a promising new data set for blocking research that gives insight into the vertical atmospheric structure, especially in light of the expected increase in data coverage that future missions will provide.

Short summary
Atmospheric blocking is a weather pattern where a stable high pressure system blocks the westerly flow at mid-latitudes. We provide, for the first time, a global perspective on blocking and related impacts, based on satellite observations from GPS radio occultation for 2006–2016. We find strong direct and remote effects on the vertical atmospheric structure revealing significant temperature and humidity anomalies up to 15 km. The observations will help for a better insight into blocking impacts.