Importance of the diurnal cycle of deep convection in understanding the role of Asian

monsoon in the UTLS transport

- perspective from multi-satellite observations

Chuntao Liu and Ed Zipser

Department of Atmospheric SciencesUniversity of Utah

Lhasa, July 2010

Outline

• What do different satellite observations tell us about the deep convection?

• Intense convection near tropopause (TRMM)• Diurnal variation of convection and clouds• Day vs. night ice cloud (CloudSat, TRMM VIRS)

thin ice Clouds (Calipso) water vapor near tropopause (MLS)• Conclusion

What do different satellite observations tell us about the deep convection?

• TRMM PR• CloudSat CPR • Caliop• Infrared

• Microwave

Infrared TB < 210

K

TRMMPR 20 dBZat 14 km

Two types of deep convection

Liu and Zipser, 2007

Deep convection with large particles at 14 km from TRMM Precipitation Radar (PR)

Rainfall ≠ Deep convection (JJA)

Clouds from infrared images (TRMM VIRS JJA)cold cloud ≠ deep convective core

Diurnal variation of deep convection and cloudsTRMM PR 20 dBZ at 14 km TRMM VIRS infrared < 235 K

TRMM VIRS infrared < 210 K

A-Train satellites sample time vs. diurnal cycles of deep convection

Liu et al., 2008, JGR

Clouds from CloudSat Profiling Radar (CPR)

Thin cloud day vs. night

Thin clouds from Calipso

Thin clouds over Asian day vs. night

Water vapor from ARUA MLS JJA 146 hPa

10% DiffDay vs. Night

Water vapor from ARUA MLS 100 hPa

5% DiffDay vs. Night

Day vs. Night Water vapor from ARUA MLS

Conclusions• TRMM observations show that there are strong diurnal cycles of

deep convection and cold cloud over land and over ocean during the Asian monsoon.

• CloudSat and Calipso show that there are large day vs. night differences in the clouds near tropopause (more clouds at the night time 1:30 AM over land)

• AURA MLS observations show that at 146 hPa, there are more water vapor at night time (1:30 AM) than the day time over land. This is almost direct opposite to the day vs. night differences of water vapor at 100 hPa.

• A-Train satellites observations show a strong diurnal variations of the cloud and the water vapor near the tropopause that might directly related to the UTLS exchange. However, more observations covering the diurnal cycles will be needed to fully understand the process.

A conceptual model over land

Tropopause

Diurnal cycles of deep convection, lightning and clouds

Liu and Zipser, 2008, GRL

Rainfall ≠ Deep convectionseasonal variations

Tropopause NCEP and COSMIC

Tropopause from NCEP and COSMIC

Calipsolayer cloud

profiles

More cloud detected at the night time 1:30 AM is due to the higher signal/noise rate of Lidar at night.

Note that layer clouds over land develop higher than over ocean, there are many possible explanations: a) due to deep convection lifting and cooling; b) due to radiative cooling and growing of thin clouds. c) note that the mean tropopause height is higher over red region.