Global Lightning Observations

Streamers, sprites, leaders, lightning: from micro- to macroscales Remote detection of lightning - information provided LIS and OTD - what they are and how they work Results from global observations Next generation Change ? Remote detection of lightning - information provided LIS and OTD - what they are and how they work Results from global observations Next generation Change ?

A schematic of grauple - ice crystal charge transfer in a thunderstorm Lightning production is related to microphysical and dynamic cloud processes. Ice interactions seem to play the major role in thunderstorm electrification. Ice interactions seem to play the major role in thunderstorm electrification. Particularly rebounding collisions of graupel and ice crystals – Non-inductive charging mechanism. Necessary conditions for thunderstorm electrification: a) str enough up-draft to grow precipitation size ice. b) ice-graupel collisions in the presence of water Necessary conditions for thunderstorm electrification: a) strong enough up-draft to grow precipitation size ice. b) ice-graupel collisions in the presence of water

Lightning Connection to Thunderstorm Updraft, Storm Growth and Decay Total Lightning —responds to updraft velocity and concentration, phase, type of hydrometeors — integrated flux of particles WX Radar — responds to concentration, size, phase, and type of hydrometeors- integrated over small volumes Microwave Radiometer — responds to concentration, size, phase, and type of hydrometeors — integrated over depth of storm (85 GHz  ice scattering) VIS / IR — cloud top height/temperature, texture, optical depth Total Lightning —responds to updraft velocity and concentration, phase, type of hydrometeors — integrated flux of particles WX Radar — responds to concentration, size, phase, and type of hydrometeors- integrated over small volumes Microwave Radiometer — responds to concentration, size, phase, and type of hydrometeors — integrated over depth of storm (85 GHz  ice scattering) VIS / IR — cloud top height/temperature, texture, optical depth

Why observe lightning? (Forecasting) Time Tornado time Tornado time Lightning Radar

p Flux Hypothesis Hypothesis: Lightning frequency (F) proportional to product of upward non precipitation ice mass flux (I) and precipitation ice mass flux (p) F = c*p*I Supported by simple calculations (Blyth et al. 2001) and lightning model results (Baker et al. 1995, 1999). Positive charge Negative charge Positive charge Negative charge Temperature Positive charge Charging zone F

STEPS Results – 6 June 2000 ‘Garden Variety’ Single Cell Storm Non- Precipitation ice mass flux [g s -1 m -2 ] * Lightning per radar volume time Precipitation ice mass flux [g s -1 m -2 ] * 10 12

How good is the apparent correlation between lightning and IWP and how does it vary between regimes? Method Create land, ocean, coastal data mask Create scatter plot of data in previous figure (0.5 x 0.5o grid) for each partition Result Noisy, but clear correlations above sample noise floor in flash density Eyeball says best fit lines would be very similar

Clarify Signal: Ocean, Coast and Land IWP Binned by Flash Density When averaged, correlation is very strong, best fit lines independent of regime. ~95% (75%) of oceanic (coast) flash density distribution in sampling noise (low flash density; <.007 fl/km 2 /day = 0.2 fl/km 2 /mo), low IWP (~ kg/m 2 ). Sampling + DE threshold + occurrence! Similar functional relationships between rain (Iiquid) – lightning vary by regime. (All rain certain pixels with detectable IWP included) TRMM PR IMP

Sample “Virtual radar” retrieval Truth Retrieval (radar) (µwave + lightning) GPROF ( cloud model) GPROF ( cloud model)

Instrument design Christian et al, J. Geophys. Res., 1989 Fast lens, narrowband filter at nm 128 x 128 CCD array, 500 fps imaging Frame-to-frame subtraction isolates lightning transients against bright daytime background Fast lens, narrowband filter at nm 128 x 128 CCD array, 500 fps imaging Frame-to-frame subtraction isolates lightning transients against bright daytime background

Measurement: Spatial Discrimination 8 km nominal spatial resolution optimizes the lightning-to-background S/N ratio. 8 km

Measurement: Temporal Discrimination CCD integration interval is set to 2 ms to minimize pulse splitting between frames and minimize integration of background signal

Measurement: Spectral Filtering Narrow band interference filter passes only light from 1nm wide oxygen mutiplet

Optical Transient Detector ( launched April, 1995 ) Optical Transient Detector ( launched April, 1995 ) Lightning Imaging Sensor ( launched November, 1997 ) Lightning Imaging Sensor ( launched November, 1997 ) Lightning Detection from Low Earth Orbit

LIS on TRMM

Lower orbit, smaller Field of View, tropical inclination History: LIS (1997-present)

High Resolution Full Climatology Annual Flash Rate Global distribution of lightning from a combined nine years of observations of the NASA OTD (4/95-3/00) and LIS (1/98-12/04) instruments

Climatology: Diurnal cycle ( Local hour )

Climatology: Diurnal cycle ( UTC Hour )

Global lightning is modulated on annual & diurnal time scales, as well as seasonally and interannually

Lightning Responsive to Interannual Variability Winter (El Niño) Winter (La Niña)

Flash Rate Density-Congo

Flash Rate Density-India

LIS Ocean Overpass

LIS Land Overpass

Major Points for Severe Weather Primary lightning signature is high flash rates and the “jump” Lightning flash rate is correlated storm intensity - higher rate implies stronger storm. Evolution of the lightning activity follows the updraft. Increasing activity means the storm intensifying; decreasing activity means the updraft is weakening. A jump in lightning activity is associated with a pulse in updraft intensity These signatures, in conjunction with other NWS assets can be used to: Separate intensifying from weakening storms Identify storms in process of going severe Quickly determine the most intense storms in a complex system Improved warning times Reduced false alarms rates Primary lightning signature is high flash rates and the “jump” Lightning flash rate is correlated storm intensity - higher rate implies stronger storm. Evolution of the lightning activity follows the updraft. Increasing activity means the storm intensifying; decreasing activity means the updraft is weakening. A jump in lightning activity is associated with a pulse in updraft intensity These signatures, in conjunction with other NWS assets can be used to: Separate intensifying from weakening storms Identify storms in process of going severe Quickly determine the most intense storms in a complex system Improved warning times Reduced false alarms rates

Lightning Sensing from GEO Climate Monitoring Storm Development Ice-phase precipitation estimates Severe Weather Now-casting Data assimilation and model inputs Atmospheric chemistry Climate Monitoring Storm Development Ice-phase precipitation estimates Severe Weather Now-casting Data assimilation and model inputs Atmospheric chemistry

GLM : Field of View at GOES West and East GOES W (75ºW) GOES E (135ºW) OTD climatology indicates lightning density Range rings indicate limits of 10, 15, 20, & 50 km pixel footprint OTD climatology indicates lightning density Range rings indicate limits of 10, 15, 20, & 50 km pixel footprint

GEO -East

Questions ?