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)