PIKART – A global catalog of atmospheric rivers
What are atmospheric rivers?
Atmospheric rivers (ARs) are filaments of horizontal water vapor transport in the lower troposphere. 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. 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. On the other hand, it can cause a variety of natural hazards, including heavy floods and landslides [ref/link].
Using AR catalogs, we can study their dynamics in detail. Here, we provide the global comprehensive PIKART catalog of atmospheric rivers along with a detailed documentation on how to use it [ref].
Perhaps have a satellite image of a specific AR and then, next to it, show its representation in the catalog?
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 [ref to ARTMIP].
The PIKART catalog is developed through a set of detection, tracking, post-processing and classification tasks:
- AR detection refers to the identification of connected regions experiencing AR conditions at a given time.
- AR tracking refers to the identification of AR trajectories in time and space.
- Post-processing tasks evaluate the consistency of the detection and tracking outputs in terms of their geometric, flow, and dynamic properties.
- Classification consists of calculating descriptors for AR trajectories and AR conditions.
We use a previously published effective detection scheme that does not require physical intensity thresholds [ref to IPART]. For tracking of 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 level and potential interactions with continental masses (e.g., inland penetration).
Add flow chart here
The PIKART catalog of atmospheric rivers
We catalog ARs to provide researchers 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
- longest available period: 1940 to 2022
- high spatial and temporal resolution (0.5° × 0.5°, 6-hourly)
- free of any physical intensity threshold for AR detection
- tracking strategy that produces long-lived trajectories
- provides more AR features, e.g., inland penetration and level classifiers
The PIKART catalog offers greater means to examine interactions of ARs with continents than previous catalogs by locating where ARs intersect continents and classifying ARs that penetrate beyond coasts further inland. It also allows more detailed studies of long-term changes in AR dynamics. A variety of regional and also a few other (quasi-)global catalogs are publicly available [ref]. Even though the PIKART catalog offers the advantages mentioned above, we encourage researchers to use the PIKART catalog in tandem with other catalogs to ensure their findings are robust.