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.

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.

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.

Africa (animation, elevation)

· Central Africa (animation, elevation)*

· Madagascar (animation, elevation)

· Southern Africa (animation, elevation)

· Western Africa (animation, elevation)*

Asia (animation, elevation)

· India (animation, elevation)

· Persian Gulf (animation, elevation)

· Philippines (animation, elevation)

· Red Sea (animation, elevation)

· Southeast Asia (animation, elevation)

· Southern India (animation, elevation)

Australasia/Oceania (animation, elevation)

· Australia (animation, elevation)

· Borneo (animation, elevation)

· Celebes (animation, elevation)

· Indonesia (animation, elevation)*

· Java (animation, elevation)

· New Guinea (animation, elevation)*

· Southeastern Australia (animation, elevation)

· Sumatra (animation, elevation)*

Europe (animation, elevation)

North America (animation, elevation)

· Caribbean (animation, elevation)

· Central America (animation, elevation)*

· Central USA (animation, elevation)

· Florida (animation, elevation)

· Hispaniola (animation, elevation)

· Panama (animation, elevation)

· Yucatan (animation, elevation)

Oceans

· Gulf Stream (animation, elevation)

· Indian Ocean (animation, elevation)

· Kuroshio (animation, elevation)

· Mediterranean (animation, elevation)

· Northern high latitudes (animation, elevation)

· Pacific ITCZ (animation, elevation)

· South Pacific (animation, elevation)

South America (animation, elevation)

· Amazon Basin (animation, elevation)

· Andes (animation, elevation)

· Argentina (animation, elevation)

· Brazil (animation, elevation)

· Central Andes (animation, elevation)*

· Northern Andes (animation, elevation)*

· Northwestern South America (animation, elevation)

Seasonal thunder hour animations

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

Global (animation)

Africa (animation)

Asia (animation)

Australasia/Oceania (animation)

Europe (animation)

North America (animation)

South America (animation)

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

Coastline and elevation data were obtained from the National Geophysical Data Center.

Questions?

Please send questions to Katrina Virts or Bob Holzworth.