WWLLN GLOBAL THUNDER HOUR CLIMATOLOGY

Introduction

The ground-based World-Wide Lightning Location Network (WWLLN) has continuously monitored global lightning since 2004.  We are pleased to make available a monthly and hourly climatology of thunder hours derived from WWLLN lightning detections.  The number of WWLLN stations has been largely consistent since 2013, so thunder hour data are available for 2013-present.  These climatologies are available for climatological research purposes.

What are thunder hours?

Conceptually, thunder hours represent the number of hours during which you would hear thunder at a particular location.  The distance at which thunder is audible depends on many factors (see summary in DiGangi et al. 2022), but for the purposes of this climatology, we assign a thunder hour to any grid box within 15 km of a WWLLN stroke during that hour.

For comparison, we also show precipitation hours derived from the Integrated Multi-satellitE Retrievals for GPM dataset (IMERG).  We define precipitation hours as the number of hours with precipitation rates greater than 5 mm hr-1.

Global diurnal thunder hour animations

WWLLN’s annual-mean climatology illustrates the global distribution of thunderstorm occurrence and its relationships with the underlying terrain.  The impact of the diurnal cycle can be illustrated by an animation of WWLLN hourly-mean thunder hours.  To directly compare the diurnal cycle from one region to another, see an animation of thunder hours as a function of local time rather than UTC.  Diurnal animations of precipitation hours as a function of UTC or local time are provided for comparison.

Continental and regional diurnal thunder hour animations

This section includes links to diurnal thunder hour animations organized by continent.  The diurnal cycle of thunderstorm occurrence is particularly fascinating in regions with both coastlines and topography, where both land/sea breezes and mountain/valley breezes modulate the convection.  Here we provide high-resolution animations for many such regions.  Favorites are marked with an *.

 

For all maps, WWLLN thunder hours are presented with units of thunder hours per year; all months are included; thin lines indicate the 100-m, 300-m, 500-m, 1000-m, and 4000-m elevation contours; and the lightning scale is logarithmic.  For comparison, we also provide animations of diurnal precipitation hours based on IMERG.

 

Africa (lightning and precipitation animations, elevation)

·      Central Africa (lightning and precipitation animations, elevation)*

·      Madagascar (lightning and precipitation animations, elevation)

·      Southern Africa (lightning and precipitation animations, elevation)

·      Western Africa (lightning and precipitation animations, elevation)*

Asia (lightning and precipitation animations, elevation)

·      India (lightning and precipitation animations, elevation)

·      Persian Gulf (lightning and precipitation animations, elevation)

·      Philippines (lightning and precipitation animations, elevation)

·      Red Sea (lightning and precipitation animations, elevation)

·      Southeast Asia (lightning and precipitation animations, elevation)

·      Southern India (lightning and precipitation animations, elevation)

Australasia/Oceania (lightning and precipitation animations, elevation)

·      Australia (lightning and precipitation animations, elevation)

·      Borneo (lightning and precipitation animations, elevation)

·      Celebes (lightning and precipitation animations, elevation)

·      Indonesia (lightning and precipitation animations, elevation)*

·      Java (lightning and precipitation animations, elevation)

·      New Guinea (lightning and precipitation animations, elevation)*

·      Southeastern Australia (lightning and precipitation animations, elevation)

·      Sumatra (lightning and precipitation animations, elevation)*

Europe (lightning and precipitation animations, elevation)

North America (lightning and precipitation animations, elevation)

·      Caribbean (lightning and precipitation animations, elevation)

·      Central America (lightning and precipitation animations, elevation)*

·      Central USA (lightning and precipitation animations, elevation)

·      Florida (lightning and precipitation animations, elevation)

·      Hispaniola (lightning and precipitation animations, elevation)

·      Panama (lightning and precipitation animations, elevation)

·      Yucatan (lightning and precipitation animations, elevation)

Oceans

·      Gulf Stream (lightning and precipitation animations, elevation)

·      Indian Ocean (lightning and precipitation animations, elevation)

·      Kuroshio (lightning and precipitation animations, elevation)

·      Mediterranean (lightning and precipitation animations, elevation)

·      Northern high latitudes (lightning and precipitation animations, elevation)

·      Pacific ITCZ (lightning and precipitation animations, elevation)

·      South Pacific (lightning and precipitation animations, elevation)

South America (lightning and precipitation animations, elevation)

·      Amazon Basin (lightning and precipitation animations, elevation)

·      Andes (lightning and precipitation animations, elevation)

·      Argentina (lightning and precipitation animations, elevation)

·      Brazil (lightning and precipitation animations, elevation)

·      Central Andes (lightning and precipitation animations, elevation)*

·      Northern Andes (lightning and precipitation animations, elevation)*

·      Northwestern South America (lightning and precipitation animations, elevation)

 

Seasonal thunder hour animations

 

We also make available seasonal thunder and precipitation hour animations, averaged over all hours of the day.

 

Global (lightning and precipitation animations)

Africa (lightning and precipitation animations)

Asia (lightning and precipitation animations)

Australasia/Oceania (lightning and precipitation animations)

Europe (lightning and precipitation animations)

North America (lightning and precipitation animations)

South America (lightning and precipitation animations)

Data access

The WWLLN global thunder hour climatology is available at 0.05º resolution for research (i.e., non-commercial use).  Further information about the dataset can be found in the readme.  When using the data, please include the following statement:  “The authors wish to thank the WWLLN (http://www.wwlln.net), a collaboration among over 50 universities and institutions, for providing the lightning data used in this paper.”

Acknowledgements

IMERG data were obtained from NASA’s Goddard Earth Sciences Data and Information Services Center (GES DISC).  Coastline and elevation data were obtained from the National Geophysical Data Center.

Questions?

Please send questions to Katrina Virts or Bob Holzworth.