The life cycle of a monsoon season viewed from TRMM, GPM ... Science … · monsoon season. The features in a life cycle include onset, active, break, revival and the withdrawal phases

The life cycle of a monsoon season viewed from TRMM, GPM and CLOUDSAT data sets

T. N. Krishnamurti, R. Deepa, Vinay Kumar and Dipak K. Sahu

Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306

MOTIVATION:

Onset

CONCLUSIONS:

Withdrawal Active Break

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Surface Energy Balance during monsoon cycle : 2014

Onset

LH-Flx SH-Flx DS-RadDL-Rad UL-Rad US-Rad-10

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Withdrawal

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Active

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LH-Flx SH-Flx DS-RadDL-Rad UL-Rad US-Rad

PHASES OF THE MONSOON

TRMM

GPM/

IMERG

CLOUDSAT AND TRMM 2A25 RADAR VIEWS

Onset Withdrawal Active

MONSOON PHASES FROM HIGH RESOLUTION CLOUD RESOLVING MODELWithdrawal Active Break

EARTH RADIATION BUDGET OVER CENTRAL INDIA

This study illustrates clouds, precipitation and the

surface energy balance during the life cycle of a single

monsoon season. The features in a life cycle include onset,

active, break, revival and the withdrawal phases of the

monsoon. The TRMM, GPM, CLOUDSAT data sets

along with results from cloud resolving model examine

typical features during these phases.

The box (20-27.5 oN and 75-82.5 oE) over central India is

chosen for earth radiation budget analysis.

The model based surface energy balance during the transitions of the monsoon phases largely

reflected the importance of clouds and soil moisture. The surface latent heat fluxes increased to

values above 100 watts/m2 and remained large during the active and even the withdrawal

phases, those values were much smaller during the break phase but not as small as in the pre-

onset phase. As to be expected the downward short wave radiation was largest during the onset

and the break phases.

(mm/day)

The TRMM and GPM based rains (mm/day), for individual days, during the monsoon phases

for 2014 are quite similar.

Cb Cu

The CLOUDSAT and TRMM 2A25 radar show deep overshooting cumulonimbus reaching

almost 16km (tropopause) during the onset phase. During the active phase the nimbostratus

and cumulonimbus are dominant. During the break phase weak nimbostratus clouds are still

present. The withdrawal phase with drier air from the north east, lifts the melting layer and

still some shallow upper tropospheric convection abounds.

Break Cu, Ns Cb

The radar reflectivity (dBZ) implied by the cloud resolving WRF model output shows deep

cumulonimbus clouds during the onset phase when warm ground temperatures and the

incursion of moisture from the south leads to very high buoyancy and very deep convection.

The active phase is dominated by nimbostratus clouds . The break and the withdrawal phases

show spotty convection.

Through TRMM, GPM, CLOUDSAT observations and modelling with the cloud resolving

WRF we found that during Monsoon phase transitions deep cumulonimbus clouds prevail

whereas in the active monsoon phase the nimbostratus provides the steady heavy rains.

The modeling confirms the role of soil moisture and clouds modulating the surface energy

balance during this transition.

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Onset

Acknowledgements: This work is supported by NASA/PMM grant No. NNX16AD83G

ONSETACTIVE

BREAK WITHDRAWAL

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Snow

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Ice

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Active Spell

Rain

Snow

CLOUD

ICE

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Active Spell

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Withdrawal

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The life cycle of a monsoon season viewed from TRMM, GPM ... Science … · monsoon season. The features in a life cycle include onset, active, break, revival and the withdrawal phases