ATM 601 Class Project: Part I
To investigate South American cold air
outbreaks, time series of 00Z 925-mb temperature at three different South American locations
(10°S, 20°S, and 30°S at 65°W) were computed from the ECMWF ERA-40 dataset for
the period 1 January 1980 through 31 December 1999*.
(*Data missing:
Nov. 1980, Dec. 1980, Dec. 1997, and Dec. 1998)
South America.
Red stars indicate locations of
interest (10°S, 65°W; 20°S, 65°W; and 30°S, 65°W)
Histograms of 925-mb temperature calculated from
these time series can be found below:
925-mb temperature was found to correlate strongly
with sea level pressure, particularly at higher latitudes:
·
At 10°S, 65°W: −0.40 (r2
= 0.16)
·
At 20°S, 65°W: −0.72 (r2
= 0.52)
·
At 30°S, 65°W: −0.83 (r2
= 0.69)
South American Cold Air Outbreaks at 10°S, 65°W
|
Top Events |
925-mb Temp. (°C) |
Loops ( T – 72h to T + 12h ) |
|||
|
1. 17 September 1980 |
10.6 |
||||
|
2. 20 July 1981 |
12.7 |
||||
|
3. 7 July 1989 |
13.4 |
||||
|
4. 8 July 1989 |
14.1 |
See Event #3 |
|||
|
5. 19 July 1981 |
14.3 |
See Event #2 |
|||
|
6. 23 September 1980 |
14.7 |
|
|
|
|
|
7. 26 June 1994 |
14.8 |
|
|
|
|
|
8. 16 September 1981 |
14.9 |
|
|
|
|
|
9. 29 June 1996 |
15.1 |
|
|
|
|
|
10. 16 August 1999 |
15.2 |
|
|
|
|
Eight independent (i.e., non-consecutive) dates of cold air outbreaks were identified from the list of ten events above. The eight independent dates were composited below to show a representative South American cold air outbreak reaching 10°S.
|
Composite (00Z) |
Mean 925-mb Temp. (°C) |
Loops ( T – 72h to T + 12h ) |
|||
|
|
13.9 |
||||