Links between the atmospheric environment and cirrus properties

Links between the atmospheric environment and cirrus properties

LINKS BETWEEN THE ATMOSPHERIC ENVIRONMENT AND CIRRUS PROPERTIES:
A SYNERGETIC APPROACH USING IR AND ACTIVE SOUNDERS AND
METEOROLOGICAL REANALYSES
C. Stubenrauch, A. Feofilov, T. Nicolas, and R. Armante
Laboratoire de Météorologie Dynamique, IPSL/CNRS, Université de Pierre et Marie Curie, Ecole Polytechnique, France
E-mail:[email protected]
Occurrence of high-level clouds
Climate monitoring with IR Sounders
TOVS, ATOVS, AIRS, CrIS,
IASI (1,2,3),
ISCCP
July
IASI-NG
TOVS Path-B, AIRS-LMD
participated in
Cloud Assessment
1rst coordinated intercomparison of 12 ‘state of the art’ global cloud
datasets (Stubenrauch et al., BAMS 2013)
>1979
/ ≥ 1995 NOAA ≥2002 / ≥ 2012 NASA ≥2006 / ≥ 2012 / ≥ 2020 CNES-EUMETSAT
local observation time: 7:30 AM/PM, 1:30 AM/PM,
9:30 AM/PM
long time series -> climate studies
increasing spectral resolution:
cloud properties from multiple satellite instruments provide coherent picture,
differences well understood:
AIRS-LMD
CAH depends on sensitivity to thin Ci (30% spread)
-> increasing vertical resolution (H2O in UT)
active lidar > IR sounders > VIS-NIR-IR imagers > multi-angle VIS imagers
retrieval day & night
RHice, aerosols & cirrus
40-45% of all clouds are high clouds (COD>0.1) CAHR=CAH/CA
CAH(AIRS) ≈ 0.33-0.35 (glb), 0.45-0.50 (trp)
IASI-LMD
(depending on atmospheric & surf ancillary data)
A-Train synergy (AIRS-CALIPSO-CloudSat):
unique opportunity for global retrieval method validation
vertical structure of cloud types
July
AIRS-IASI synergy: diurnal cycle of high clouds
AIRS-LMD L2 cloud data distributed by ICARE: http://www.icare.univ-lille1.fr/
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TOVS Path-B & AIRS-LMD L3 cloud data available at http://climserv.ipsl.polytechnique.fr/gewexca
cloud pressure (CP) & optical depth (COD) or cloud emissivity (CEM)
CEM class :
0.05-0.25
0.25-0.5
0.5-0.75
0.75-0.9
0.9-1
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ISCCP
day
day + night
2
Hilton et al., BAMS 2012
CEM-CP high-cloud Weather States
42 CEM-CP classes -> 13 CEM-CP Weather States; 5 including high clouds:
AIRS-LMD
vertical extent ISCCP
per cloud class:
incl subvis Ci
excl subvis Ci
TOVS-B
AIRS-LMD
IASI-LMD
geographical distribution &
seasonal cycle similar
Identification of cloud classes
CALIPSO
RH profiles
CEM
vertical extent increases with CP & CEM;
similar contributions of single layer Ci & Ci + low cld
Vertical structure from coloc. CALIPSO-CloudSat GEOPROF (Mace et al. 2009)
WS’s distinct vertical &
horizontal structures &
radiative effects
vertical structure per cloud class
Distribution of ISCCP WS’s per AIRS-LMD WS
Comparison with ISCCP
Clouds extended objects, driven by dynamics -> cloud systems
(Tselioudis et al. 2013):
good agreement;
thin Ci, Ci over low cld : often indicated by ISCCP
as fair weather
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mesoscale grid: occurrence of these classes -> weather states (Tselioudis et al. 2013)
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Ice Supersaturation: Ci occurrence & impact of contrails
Detection of ice supersaturation (ISS)
probability of ISS presence in layer
by calibration with MOZAIC (commercial aircraft)
200-250 hPa
Lamquin 2009; Lamquin et al., ACP 2012
from CALIPSO
ISS important for understanding Ci formation & for detecting regions where
persistent aviation contrails may develop
IR Sounders retrieve water vapour within atmospheric layers of km’s
=> underestimation of RHice : AIRS peak for cirrus at 70% (instead of 100%)
improved spectral resolution : IASI peak for cirrus at 80-85%
frequency of potential contrail situations
AIRS
from AIRS
ISS often occurs in vertical layers < 500 m
Ci occurrence increases with ISS occurrence
stronger increase in tropics than in midlat
(different formation mecanism?)
tropics
AIRS
saturated region
integrated from ISS occurrence
weighted by flight altitude air traffic density
Stubenrauch and Schumann GRL 2005
25
pot. Contrails
clr+thin Ci
22,5
AIRS
IASI
eff. cloud amount
TOVS
extract meteorological situations
for potential contrails
Increase of thin cirrus over Europe
IASI
17,5
15
12,5
10
7,5
2.8-3.5% (±1.5%) per decade
~0.19% - 0.25% per decade (all situations)
5
RHi (%), radiosondes
20
Europe
5
87,5
88
88,5
89
89,5
90
90,5
91
91,5
92
92,5
93
93,5
94
94,5
time (years)
95
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Diurnal cycle of high-level clouds
Cirrus ice crystals <-> IWP <-> mesoscale humidity, winds
ISCCP (3hourly): max of high clouds in evening (significant over tropical land) (Cairns Atm. Res. 1995)
TOVS (2 sat, time drift) : Cirrus increase during afternoon & persist during night, thickening
Stubenrauch et al. Atm. Res. 2004
(Stubenrauch et al. J. Climate 2006)
on average smaller than latitudinal & seasonal variations, often localized
=> when using 2 different instruments (AIRS-IASI synergy), use same ancillary data (ERA-Interim)
IWP & De increase with atmospheric water vapor
largest IWP in case of strong vertical updraft
smallest De in case of strong hor. & vert. winds
AIRS 1:30AM
IASI 9:30AM
January 2009
AIRS 1:30PM
IASI 9:30PM
TOVS-ERA synergy
Guignard et al. ACP 2012
CAH(t)-0.25*S i=1,4CAH(ti)
ITCZ: high-level clouds develop during the evening & persist during night (in agreement with TOVS)
NH winter land: cirrus develop in the morning / afternoon
Fraction of aggregate-like ice crystals
& De increase with IWP
AIRS-LMD retrieval
Outlook:
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• build a synergetic climate database including Ci properties, ISS probability, dynamics
• Lagrangian studies of atmospheric flow linked to cirrus, in cooperation with B. Legras (LMD)
• link ISS & dust loading to Ci
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