SH circulation patterns shape Antarctic snowfall
BAM, SAM, and PSA polarities rearrange Antarctic precipitation, with PSA1 explaining ~40% of daily variability in West Antarctica.
Source
The Signature of Southern Hemisphere Atmospheric Circulation Patterns in Antarctic Precipitation
Study at a glance
- Design
- Other — Composites of RACMO2 Antarctic precipitation for BAM/SAM/PSA circulation phases (1979–2013)
- N
- 35-year reanalysis/model composite study; not a discrete sample N
- Population
- Antarctic Ice Sheet precipitation under Southern Hemisphere circulation modes
- Outcome
- Spatial precipitation rearrangements; PSA1 explaining ~40% of West Antarctic daily variance
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Authors composited 1979–2013 RACMO2 precipitation and ERA-Interim moisture fluxes for days when BAM, SAM, PSA1, or PSA2 indices exceeded ±1, and examined Byrd and Law Dome extremes.
What they found
BAM+ wets coastal East Antarctica; SAM+ wets the western Peninsula but dries the lee and the Plateau; PSA1+ can more than double Marie Byrd Land/Ross Ice Shelf precipitation. PSA1 accounts for ~40% of daily West Antarctic precipitation variance. Annual-mean index trends are not significant over 35 years.
The limits
What it doesn't show
RACMO is still a model of precipitation, not gauges. Daily modes explain only modest fractions of day-to-day noise. 1979–2013 cannot project 21st-century SAM/PSA changes.
Key terms
- BAM
- Southern baroclinic annular mode: leading EOF of SH eddy kinetic energy.
- SAM
- Southern Annular Mode: first EOF of SH 500 hPa height.
- PSA1/PSA2
- Pacific–South American teleconnection patterns (2nd and 3rd 500 hPa EOFs).
- RACMO2
- 27 km regional atmospheric model forced by ERA-Interim, used for Antarctic precipitation.
- Precipitation shadow
- Lee-side drying of the Antarctic Peninsula under SAM+ westerlies.
Flashcards
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Quiz yourself
PSA1’s share of West Antarctic daily precipitation variability is about:
Common questions
Which pattern most controls West Antarctic daily snow?
PSA1, ~40% of daily precipitation variability.
What happens to Peninsula precipitation under SAM+?
Increase on the west, rain-shadow decrease on the east.
Were annual-mean circulation trends significant?
No, not over 1979–2013; SAM+ did increase in summer.
How are +/− days defined?
Index >1 or < −1 standard deviation.
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