PIKART

PIKART – A comprehensive global catalog of atmospheric rivers

The PIKART Atmospheric River Catalog is a global, high-resolution dataset of atmospheric rivers spanning 1940–2023. It is designed for reproducible research on AR dynamics from the tropics to the poles.

Below, we provide an overview of the catalog's properties and how you to access it.

What are atmospheric rivers?

Atmospheric rivers (ARs) are filaments of horizontal water vapor transport in the lower atmosphere. Along their tracks, they act as ‘global conveyor belts’ of atmospheric moisture. Single ARs can carry more water than the Amazon river. At any given time, there are about eleven ARs somewhere around the globe. Landfalling ARs can be a curse or a blessing: AR-driven rainfall provides vital freshwater to arid regions and is known to bust droughts, e.g., in California (Dettinger, 2013). On the other hand, strong ARs can cause extreme precipitation (Vallejo-Bernal et al., 2023) and lead to a variety of natural hazards, including floods (Collister & Mattey, 2008), landslides and even heatwaves (Scholz & Lora, 2024)!

By cataloging AR, we can systematically study their dynamics. Here, we provide the global comprehensive PIKART catalog of ARs along with a detailed documentation on how to use it.

How do we catalogue atmospheric rivers?

Most AR detectors isolate ARs as atmospheric moisture anomalies from fields of integrated vapor transport (IVT). Several approaches with individual strengths and weaknesses have been designed and compared (Rutz et al., 2019).

The PIKART catalog is developed through a set of detection, tracking, post-processing and classification tasks:

1. AR detection refers to the identification of connected regions experiencing AR conditions at a given time.
2. AR tracking refers to the identification of AR trajectories in time and space, considering processes like merging and splitting of ARs.
3. Post-processing tasks evaluate the consistency of the detection and tracking outputs in terms of their geometric, flow, and dynamic properties.
4. Classification consists of calculating descriptors for AR trajectories and AR conditions.

Detailed description of the detection algorithm and data can be found in the paper:

• S. M. Vallejo-Bernal et al., "PIKART: A Comprehensive Global Catalog of Atmospheric Rivers", Journal of Geophysical Research: Atmospheres, 2025, pp. . doi:10.1029/2024JD041869

With our approach, we build on IPART-1, a previously published effective detection scheme that defines magnitude thresholds endogenously from synoptic-scale moisture dynamics (Xu et al., 2020). To track ARs, we consider the spatial proximity and morphological similarity of AR shapes. AR trajectories in the PIKART catalog are allowed to lose intensity if they are able to recover it fast enough. Thus, AR life cycles are not fragmented due to genesis, termination or interactions with other ARs. Finally, we impose constraints that discriminate the identified ARs against a variety of other atmospheric phenomena and classify all AR trajectories with respect to their rank and potential interactions with continental masses (e.g., inland penetration).

The PIKART catalog of atmospheric rivers

We catalog ARs to provide researchers, resource & risk manager and anyone interested with a reliable foundation for reproducible studies on AR dynamics. The PIKART catalog offers several advantages compared to other AR catalogs:

• Fully global extent, including the tropics.
• Based on ERA5 data: 1940 to 2023.
• Also available based on MERRA2 data.
• High spatial and temporal resolution (0.5° × 0.5°, 6-hourly).
• Adaptive intensity thresholds for AR detection.
• Tracking strategy that produces long-lived trajectories and allows physically-sound time gaps.
• Provides many AR features, e.g., AR ranks, land intersection coordinates and a novel inland penetration index.

Even though the PIKART catalog offers these compelling advantages, we encourage researchers to use the PIKART catalog in tandem with other catalogs to ensure their findings are robust.

References

1. C. Collister, D. Mattey, "Controls on water drop volume at speleothem drip sites: An experimental study", Journal of Hydrology, vol. 358, no. 3-4, 2008, pp. 259–267. doi:10.1016/j.jhydrol.2008.06.008
2. M. D. Dettinger, "Atmospheric Rivers as Drought Busters on the U.S. West Coast", Journal of Hydrometeorology, vol. 14, no. 6, 2013, pp. 1721–1732. doi:10.1175/jhm-d-13-02.1
3. J. J. Rutz et al., "The Atmospheric River Tracking Method Intercomparison Project (ARTMIP): Quantifying Uncertainties in Atmospheric River Climatology", Journal of Geophysical Research: Atmospheres, vol. 124, no. 24, 2019, pp. 13777–13802. doi:10.1029/2019jd030936
4. G. Xu et al., "Image-processing-based atmospheric river tracking method version 1 (IPART-1)", Geoscientific Model Development, vol. 13, no. 10, 2020, pp. 4639–4662. doi:10.5194/gmd-13-4639-2020
5. S. M. Vallejo-Bernal et al., "The role of atmospheric rivers in the distribution of heavy precipitation events over North America", Hydrology and Earth System Sciences, vol. 27, no. 14, 2023, pp. 2645–2660. doi:10.5194/hess-27-2645-2023
6. S. R. Scholz, J. M. Lora, "Atmospheric rivers cause warm winters and extreme heat events", Nature, vol. 636, no. 8043, 2024, pp. 640–646. doi:10.1038/s41586-024-08238-7
7. S. M. Vallejo-Bernal et al., "PIKART: A Comprehensive Global Catalog of Atmospheric Rivers", Journal of Geophysical Research: Atmospheres, 2025, pp. . doi:10.1029/2024JD041869