1998/1999 Arctic MERRA-2 Wind
Daily progression and annual means
The daily progression through the 1998/1999 season of the various wind statistics, comparing 1998/1999 to the climatology of all other seasons. Also, annual plots of statistics for monthly means. Clicking a link will bring up, in a new window, a PDF vector plot or a plain-text ASCII data file that is suitable for input into any program. The annual plots show the range of daily values that go into each year's average with shading.
60°N zonal wind
The average east-west (zonal) wind speed for 60°N. This is near the peak of the polar jet maximum. A 45 m s-1wind speed is equal to 100 mph. (Plot is shown for 1 October–30 June on the 100-hPa surface.)
45°–75°N zonal wind
The average east-west (zonal) wind speed for 45°N to 75°N. This is near the peak of the polar jet maximum. A 45 m s-1wind speed is equal to 100 mph. (Plot is shown for 1 Octoberl–30 June on the 100-hPa surface.)
The Arctic is circled by a strong jet stream in the stratosphere (above 12 km or 39,000 ft). Looking down on the South Pole, this jet stream flows around Antarctica in a counterclockwise sense. This jet stream isolates air over the Arctic polar region from air in the midlatitudes. The region poleward (inside) of this jet stream is called the Arctic polar vortex. A stronger jet stream flow results in greater isolation of polar air from midlatitude air (less mixing). The air inside the Arctic polar vortex is also much colder then midlatitude air. Wave events distort the polar vortex and allow for greater mixing inside the vortex. These events can result in major and minor polar warmings.
The data are from the Modern-Era Retrospective analysis for Research and Applications, Version 2 ( MERRA-2) assimilation, produced by the Goddard Earth Observing System Data Assimilation System (GEOS DAS). MERRA-2 uses a version of the GEOS model with the Gridpoint Statistical Interpolation (GSI) atmospheric analysis developed jointly with NOAA/NCEP/EMC. Since it takes about two months to incorporate these data into the statistics, we supplement the MERRA-2 assimilation with the GEOS FP assimilation system that provides analyses and forecasts. This assimilation system is also produced by the GEOS DAS. and integrates forefront versions of the GEOS atmospheric general circulation model with advanced data assimilation techniques, using a broad range of satellite observations.