On the relationship of in-cloud convective turbulence and total lightning

Wiebke Deierling, John Williams, Sarah Al-Momar, Bob Sharman, Matthias Steiner and Cathy Kessinger

Our Purpose

• Examine possible relationships between lightning occurrence and turbulence production for different storm types

• Examine relationships over CONUS first because of good data coverage

• Extend examination to oceanic storms in the near future • If successful, GLM on GOES-R may provide valuable

information for underserved regions to help identify regions of convective turbulence

Background – Updraft and Lightning

Reflectivity 5.5 km MSL- Evidence that updraft volume correlates with total lightning (Wiens et al. 2005, Deierling et al. 2008)

- Large updraft volumes of higher updraft speeds are capable of producing more hydrometeors in the mixed ice phase region, promoting electrification

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+ −−

TurbulenceTurbulence

Turbulence

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Question: How does convective turbulence relate to total lightning?

Data Sets Used

• Turbulence intensity:– NEXRAD Turbulence Detection

Algorithm (NTDA) Eddy Dissipation Rate (EDR)

• Radar reflectivity:– NTDA mosaic

NTDA Turbulence

PIDEast-West Distance [km]

Nor

th-S

outh

Dist

ance

[k

m]

Height [km

Hei

ght

[km

Hei

ght

[km

Time [ms]

LMA Detected Lightning• In-Cloud and Cloud-to-Ground

Lightning:– Measured by Lightning Mapping

Array (LMA) at New Mexico and Northern Colorado LMA Flash Extent

NTDA Reflectivity

NTDA EDR

Growing Air Mass Storms at 21:55UTCEDR – light-moderate-severe color scale

EDR

LMA 3D lightningRadar Reflectivity

Higher Turbulence and lightning in upper levels of cloud.

Highest turbulence above highest lightning VHF sources above highest radar reflectivity.

Mature Air Mass Storms at 22:20UTC

Radar Reflectivity

EDR – light-moderate-severe color scale

EDR

LMA 3D lightningRadar Reflectivity

Decaying Air Mass Storms at 23:20UTC

EDR – light-moderate-severe color scale

EDR

LMA 3D lightningRadar Reflectivity

Horizontal LMA Flash Extent

Radar reflectivity volume>35 dBZ for T<0C

EDR Volumes for T<0C Blue: EDR>0.15Red: EDR>0.3 (multiplied by 5) ED

R Vo

lum

e [k

m3 ]

Refl.

Vol

. [km

3 ]LM

A Fl

ash

Exte

nt [fl

/km

2 ]

EDR

Volu

me

of E

DR>

0.3

[km

3 ]

Refl.

Vol

. of Z

>35d

BZ [k

m3 ]

LMA Flash Extent [fl/km2] LMA Flash Extent [fl/km2]

Variations by Lifecycle

Developing storm

Mature storm

Decaying storm

r=0.75 r=0.87

Total Lightning vs. Z>35dBZ volume for T<0C

Total Lightning vs. EDR>0.3 volume for T<0C

Horizontal Cross-Section with Height

Light

Moderate

Severe

Light

Moderate

Severe

Reflectivity 5.5 km MSL

EDR FL 150 EDR FL 330

Extreme Extreme

EDR values at different height levels and horizontal lightning extent contours (magenta).

During growth period of storms, the turbulent regions tend to:

Have a larger area of MOD turbulence at higher levels within storms

Are horizontally aligned (not necessarily vertically aligned) with lightning regions

5 min Total Lightning

EDR

Volu

me

of E

DR>

0.2

Best correlation for total EDR volumes for EDR values >0.16-0.22

New Mexico air mass storms, total lightning correlates best to light-moderate turbulence at FL300-400

Total Ltg & EDR volume>0.2 of Air Mass Storms in New Mexico over 2 weeks

R=0.89

CO Severe Storms – Mature Stage

NTDA EDRLMA 3D lightning

NTDA Radar Reflectivity Higher turbulence regions often above highest VHF source densities above highest radar reflectivity

Severe Storms – CO

NTDA EDRLMA 3D lightning

NTDA Radar Reflectivity Severe storm cells on 27 May 2013

SPC reports of several tornadoes, 1 inch hail, and 60 knot winds

VHF sources 35 dBZ Refl.

EDR>0.15 EDR>0.3

EDR>0.4EDR>0.3EDR>0.15

EDR

Volu

me

[km

3 ]

Time [UTC]

Severe Storms – COTime –Height histograms

Time [UTC]

Refl.

Vol

. > 3

5dBZ

[km

3 ]Fl

ash

Exte

nt [fl

/km

2 ]

Higher lightning frequencies relate to higher turbulence intensities

Most storms exhibited charge centers in between the maximum reflectivity cores and peak turbulence during a storms mature stage

Regions of higher EDR are horizontally collocated with higher flash extents for air mass storms

EDR and lightning relationship looks promising for air mass storms but more complicated for severe storms, needs more investigation

Look at more storm types, including oceanic storms Compare with modeling studies

Summary & Outlook

Thank you!