Atmospheric Circulation Patterns: Northern and Southern Hemisphere Winter Dynamics
This overview explores the atmospheric circulation patterns during winter months in both the Northern and Southern Hemispheres. It examines the role of wind belts, angular momentum, and the geostrophic balance at various altitudes (3 km, 5.5 km, 9 km). The study highlights temperature and pressure variations, the impact of land and ocean interactions, and the organization of storm tracks across both hemispheres. Additionally, it discusses the variability in the length of the day and the differential effects of climate on precipitation, demonstrating the complexities of global atmospheric dynamics.
Atmospheric Circulation Patterns: Northern and Southern Hemisphere Winter Dynamics
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Presentation Transcript
Angular momentum Change in length of day (10-3s) time • Length of the day varies by milliseconds due to climate
Wind as a function of latitude and height Dec/Jan/Feb Jun/Jul/Aug • Note the stronger jet in the winter hemisphere
Temperature as a function of latitude and height Dec/Jan/Feb Jun/Jul/Aug Note the warmer summer hemisphere (duh)
Northern hemisphere winter (Dec Jan Feb) – Sea level pressure Icelandic Low Aleutian Low Siberian High
Northern hemisphere winter (Dec Jan Feb) – Surface wind Note the approximate geostrophic balance (c.f. pattern of surf. pressure)
Northern hemisphere Winter circulation – pressure at 3km What is the Geostrophic balance here?
– pressure at 5.5km Northern hemisphere Winter circulation What is the Geostrophic balance here?
– pressure at 9.0km Northern hemisphere Winter circulation What is the Geostrophic balance here?
Northern hemisphere - temperature difference from zonal average in lower troposphere. (0 to 5 km)
Heat flux from surface to atmosphere (Winter) Wm-2 Cooling over land, heating over ocean (up to 4000W/m2 in a big storm)
Northern hemisphere winter (Dec Jan Feb) – Precipitation rate Precipitation organized into storm tracks in Atlantic and Pacific basins
Storm tracks in the atmosphere Density of tracks of storms in DJF, northern hemisphere
Southern hemisphere winter (Jun Jul Aug) – Sea level pressure Pattern is much more zonal (east west) than Northern hemisphere
Southern hemisphere winter (Jun Jul Aug) – Surface wind Note the approximate geostrophic balance (in southern hemisphere!)
Southern hemisphere winter circulation- pressure at 5.5km What is the Geostrophic balance here?
Southern hemisphere: heat flux from surface to atmosphere (Winter) Wm-2
Southern hemisphere winter precipitation (ish!) What about the pattern here?
Storm tracks in the atmosphere Density of tracks of storms in JJS, southern hemisphere Distributions of storm are much more uniform