DYNAMO—DYNAmics of the MJOShipboard operation of the NASA/TOGA radarDYNAMO—DYNAmics of the MJOShipboard operation of the NASA/TOGA radar

Photo courtesy of T. LangPhoto courtesy of T. Lang

September 2011 – February 2102

NASA TOGA radar

Moum et al. 2014

SST patternquiteinteresting!Ocean reallynever “recovered” after MJO2.

Prolonged periods (> 24 hours) ofnegative net flux rare in tropics. Theseare periods when ocean cools throughloss of latent and sensible heat (SST> Tair)and reduction in solar insolation. This is part of the story!

SST

AIR

Strong westerlies in MJO2

Yoshida-Wyrtki jet, westerly surface current.

Yoshida-Wyrtki jet, westerly surface current.

Mixing promoted by strong vertical shear brings cool, salty water to the surface.

Shear induced mixing is significant component for lowering the SST’s,in addition to surface fluxes/insolation. MJO2 resulted in a major cooling of the upper ocean. Did this have an impact on MJO3, which was muchweaker?

Shallow thermocline in Indian O. allows access to cooler water.

Mixing promoted by strong vertical shear brings cool, salty water to the surface.

Shear induced mixing is significant component for lowering the SST’s,in addition to surface fluxes/insolation. MJO2 resulted in a major cooling of the upper ocean. Did this have an impact on MJO3, which was muchweaker?

Shallow thermocline in Indian O. allows access to cooler water.

Moum et al. 2014

Surface wind stress

Daily Evolution: Convective Population

1. In phase:

RH, Rainrate,

Strat. Rain.

2. In phase:

SST, Lightning,

CAPE.

Role of Aerosols?

A little background…

Z

Kdp

Oklahoma

Kdp proportional to mass content andmass-weighted oblateness ratio

Based on computationsof Z and Kdp from DSDassumptions

Based on computationsof Z and Kdp from DSDassumptions

0.5 deg elevation angle0.5 deg elevation angle

50

40

30

2 4 6

deg/km Difference in H,V phase in degrees

RainRain

Kdp is a measure of the difference in wave propagation between H and V polarizations; sensitive to non-spherical particles

a

b

0

Differential Reflectivity

Reflectivity

N-Pol in Oklahoma

Results consistent withactive coalescence growthand ice-based precipitation.

Resulting from highermoisture contents, higherfreezing level, collisionalbreakup, etc.

N-Pol data are clearly goingto help us better understandDSD variability and the physics leading to the variability.

N-Pol in Oklahoma

Results consistent withactive coalescence growthand ice-based precipitation.

Resulting from highermoisture contents, higherfreezing level, collisionalbreakup, etc.

N-Pol data are clearly goingto help us better understandDSD variability and the physics leading to the variability.

Colorado and “tropical”eventsColorado and “tropical”events

Warm rainWarm rain

Ice basedIce based

Normalized density of points expressed as a percentageNormalized density of points expressed as a percentage

N-POLN-POL

26 Jan 1999 EAST case.Stronger convection,higher CAPE.

24 Feb 1999WEST case.Lower CAPE,monsoon-like regime.

EAST WEST

0

SubtledifferencesbetweenEast andWest

KDOX 10/28/2012: Merger of Sandy's outer bands with N/S oriented front. This confluence caused significant precipitation along the western shore of the Chesapeake Bay.

Pretty much a tropical regime….