tropopause height diagnostics
DESCRIPTION
Tropopause Height Diagnostics. Motivation tropopause is important feature of the observed atmosphere determined by conditions in both tropo- and stratosphere position of tropopause is relevant for climate studies: e.g. cross tropopause transport - PowerPoint PPT PresentationTRANSCRIPT
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Tropopause Height Diagnostics
Motivation
• tropopause is important feature of the observed atmosphere
• determined by conditions in both tropo- and stratosphere
• position of tropopause is relevant for climate studies:
e.g. cross tropopause transport
indicator of climate change
Method
• apply same criterion as for determination from radiosondes:
a. lowest level at which lapse rate decreases to 2 K/km b. 2 km deep layer above must not exceed critical lapse rate
• problem of coarse vertical resolution > vertical interpolation
• limit for heights to be valid: 450-75 hPa failure rate: overall 0.1%, mostly over Antarctica during JJA
• rms: 30-40 hPa in extratropics, 10-20 hPa in tropics
Input Data
• 3D temperature field: daily or monthly data
• all comparisons on standard pressure levels
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Tropopause pressure (hPa)daily reanalysis-1: CDC vs. TJR
DJF 1983-1998 JJA
CD
CT
JR
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DJF 1983-1998 JJA
reanalysis-1 vs. reanalysis-2re
an.
2re
an.
1
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DJF 1983-1998 JJA
reanalysis-1: daily vs. monthly datam
on
thly
dat
ad
aily
dat
a
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DJF 1983-1998 JJA
p11/exp55danA
M2
mo
nth
lyr1
mo
nth
ly
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DJF 1983-1998 JJA
exp42 vs. exp55danex
p42
- r
1ex
p55
dan
- r
1
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DJF 1983-1998 JJA
p12L32_3 vs. exp55danp
12L
32_3
- r
1ex
p55
dan
- r
1
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DJF 1983-1998 JJA
CAM 2.0.1C
AM
mo
nth
lyr1
mo
nth
ly
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DJF 1983-1998 JJA
NSIPPN
SIP
P m
on
thly
r1 m
on
thly
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DJF 1983-1998 JJA
NCEP SFMS
FM
mo
nth
lyr1
mo
nth
ly
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Summary
rms exp55 exp42 p12L32 CAM2 NSIPP SFM
DJF 16 19 26 22 20 42
JJA 13 16 25 11 16 40
• AM2 tropopause height is generally too low (too high pressure), consistent with a too cold troposphere and too warm stratosphere
• biases over northern extratropics: +30 hPa in DJF (ca. -600 m) +10 hPa in JJA (ca. -200 m)
• tropical biases: +8 hPa in DJF (ca. -600 m) +3 hPa in JJA (ca. -200 m)
• biases over southern extratropics: -20 hPa in DJF +20 hPa in JJA
• global mean rms of tropopause pressure (hPa):