Upload
elvis
View
55
Download
0
Tags:
Embed Size (px)
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 Presentation
Citation preview
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
Tropopause pressure (hPa)daily reanalysis-1: CDC vs. TJR
DJF 1983-1998 JJA
CD
CT
JR
DJF 1983-1998 JJA
reanalysis-1 vs. reanalysis-2re
an.
2re
an.
1
DJF 1983-1998 JJA
reanalysis-1: daily vs. monthly datam
on
thly
dat
ad
aily
dat
a
DJF 1983-1998 JJA
p11/exp55danA
M2
mo
nth
lyr1
mo
nth
ly
DJF 1983-1998 JJA
exp42 vs. exp55danex
p42
- r
1ex
p55
dan
- r
1
DJF 1983-1998 JJA
p12L32_3 vs. exp55danp
12L
32_3
- r
1ex
p55
dan
- r
1
DJF 1983-1998 JJA
CAM 2.0.1C
AM
mo
nth
lyr1
mo
nth
ly
DJF 1983-1998 JJA
NSIPPN
SIP
P m
on
thly
r1 m
on
thly
DJF 1983-1998 JJA
NCEP SFMS
FM
mo
nth
lyr1
mo
nth
ly
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):