On the instantaneous linkages between cloud vertical structure and large -scale climate
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Transcript of On the instantaneous linkages between cloud vertical structure and large -scale climate
On the instantaneous linkages between cloud vertical structure and large-scale
climate Ying Li
Colorado State University
• Merged CALIPSO/CloudSat data(2B-GEOPROF-LIDAR product; June 2006–April 2011)
cloud incidence is derived from cloud fractione.g., 25% indicates a cloud is observed 25% of
the time within the sample volume
• Meteorological fields obtained from1) Collocated CloudSat ECMWF-AUX auxiliary
data product – instantaneous relationships (∼108 profile
measurements)2) ERA-Interim reanalysis – in some selected cases – month-to-month variability (∼105 monthly-
mean profile measurements)
Data:
A range of large-scale meteorological parameter
1. sea surface temperature (SST)
2. lower tropospheric stability (LTS; θ3km − θsurface)
3. mid-tropospheric vertical motion (−ω500)
4. storm track activity: RMS (ω’500)
5. tropopause temperature (TT)
6. upper tropospheric stability (UTS; θtropopause − θtropopause−3km)
From Li and Thompson (JGR, 2013)
The role of stratospheric wave driving in linking the TT and UTS, and space/time distribution of upper tropospheric cloud incidence
Cold tropopauseWeak static stability Lift of tropopause
Increased cloud incidence
A range of large-scale meteorological parameter
1. sea surface temperature (SST)
2. lower tropospheric stability (LTS; θ3km − θsurface)
3. mid-tropospheric vertical motion (−ω500)
4. RMS (ω’500) and dT/dy in the storm track region
5. tropopause temperature (TT)
6. upper tropospheric stability (UTS; θtropopause − θtropopause−3km)
Peak at 303 KMinimum 295-300 KMaximum below 285 K
Increase with decreasing SSTe.g., Klein and Hartmann 1993; Wood and Bretherton, 2006
Shallow maximum 272 – 278 K Mid/high lat. regime
Vertical structure of cloud incidence as a function of SST over the Global Ocean
SST between 272 – 286K
SST between 272 – 286K
A range of large-scale meteorological parameter
1. sea surface temperature (SST)
2. lower tropospheric stability (LTS; θ3km − θsurface)
3. mid-tropospheric vertical motion (−ω500)
4. RMS (ω’500) and dT/dy in the storm track region
5. tropopause temperature (TT)
6. upper tropospheric stability (UTS; θtropopause − θtropopause−3km)
Influences of lower tropospheric stability
Maximum at high LTS
e.g., stratocumulus clouds
Maximum at low LTS
e.g., stratus associated with extratropical synoptic storms)
Dual maxima: different types of clouds throughout the mid/high latitude
Heig
ht (k
m)
A range of large-scale meteorological parameter
1. sea surface temperature (SST)
2. lower tropospheric stability (LTS; θ3km − θsurface)
3. mid-tropospheric vertical motion (−ω500)
4. RMS (ω’500) and dT/dy in the storm track region
5. tropopause temperature (TT)
6. upper tropospheric stability (UTS; θtropopause − θtropopause−3km)
Influences of mid-tropospheric vertical motion
Increases as w
1% per 10 hPa d-1
High-top clouds tends to occur in regions of rising motion/low pressure
Low-top clouds tends to occur in regions of sinking motion/high pressure
Bimodal vertical distribution is due to:• Passage of the cloud frontal system (low-level clouds behind the
cold frons are associated with upper-level clouds ahead of the cold front)
• Superpostion of alternating cyclonic and anticyclonic weather systems
Heig
ht (k
m)
Vertical structure of the linkages between anomalous cloud incidence and vertical motion over the extratropical ocean (30-90S/N)
Regions of anomalously upward motion are associated with anomalous high cloud incidence
~3% per 10 hPa d-1
Heig
ht (k
m)
A range of large-scale meteorological parameter
1. sea surface temperature (SST)
2. lower tropospheric stability (LTS; θ3km − θsurface)
3. mid-tropospheric vertical motion (−ω500)
4. RMS (ω’500) and dT/dy in the storm track region
5. tropopause temperature (TT)
6. upper tropospheric stability (UTS; θtropopause − θtropopause−3km)
Cloud incidence in the combined four storm track regions• Peak at jet stream level &
Increases with increasing storm track amplitude
• e.g., nimbostratus, deep convective clouds
Low level clouds decease with increasing storm track amplitude
A range of large-scale meteorological parameter
1. sea surface temperature (SST)
2. lower tropospheric stability (LTS; θ3km − θsurface)
3. mid-tropospheric vertical motion (−ω500)
4. RMS (ω’500) and dT/dy in the storm track region
5. tropopause temperature (TT)
6. upper tropospheric stability (UTS; θtropopause − θtropopause−3km)
Increases as TT decreases(1.5-2% K-1)
Increases as UTS decreases~8% per K km-1)
Influences of tropopause temperature (TT) and upper tropospheric stability (UTS)
Vertical structure of the linkages between anomalous cloud incidence and static stability over the extratropical ocean (30-90S/N)
Regions of anomalously low static stability are associated with anomalous high cloud incidence
~2% per K km-1
Summary
The results in study
• provide a baseline for evaluating physical parameterizations of clods in GCM
• serve as a reference for interpreting the signature of large-scale atmospheric phenomena in cloud vertical structure Li, et al (GRL, 2014)