The Atmospheric River Tracking Method Intercomparison Project (ARTMIP): Quantifying Uncertainties in Atmospheric River Climatology

November 25, 2019

We are pleased to announce the online publication of a paper entitled, “The Atmospheric River Tracking Method Intercomparison Project (ARTMIP): Quantifying Uncertainties in Atmospheric River Climatology” (Rutz et al. 2019). This paper is the cornerstone of the ARTMIP Tier 1 experiment, in which 20+ researchers applied their atmospheric river (AR) identification and tracking methods to the same data set (MERRA v2), same time period (1980-2017), and overlapping regions of the globe. The result is a rich data set that was used to quantify the uncertainty in current AR climatology that arises due to the number of methods now in the published literature. This paper does so by examining metrics such as AR frequency, duration, seasonality, and many other novel methods of comparison. An example of this uncertainty at one time step is shown in the figure below, which highlights the different spatial footprints of an AR identified by a number of different ARTMIP methods. In general, this study highlights the fact that methods with more restrictive AR identification and tracking criteria tend to have weaker statistics in terms of AR climatology, while the statistics for methods with less restrictive criteria are more robust, as more ARs are identified. The ARTMIP Tier 1 data set is available (housed on the NCAR/UCAR Climate Data Gateway at doi:10.5065/D6R78D1M), and can be used by other researchers to further assess the uncertainty that arises as a result of different AR tracking and identification methods. Future work (ARTMIP Tier 2) will use a similar approach to evaluate the uncertainty of AR climatology under several future climate scenarios.

For more information about ARTMIP, visit the ARTMIP web page.

Figure 1: Example of how AR identification and tracking methods differ over the northeastern Pacific, based on MERRA v2 data from 0000 UTC 15 February 2014. Gray shading represents IVT (kg m^-1 s^-1), and colored contours represent the spatial regions designated as ARs by the various methods. Note that only algorithms available in this region are shown. Additionally, some methods available for this region do not identify an AR at this time (‘payne’, ‘pnnl1_hagos’,and ‘pnnl2_hq’). Please see Figure 5 and Table 1 in the manuscript for more information about methods shown.

Rutz, J. J., Shields, C. A., Lora, J. M., Payne, A. E., Guan, B., Ullrich, P., et al. (2019): The Atmospheric River Tracking Method Intercomparison Project (ARTMIP): Quantifying Uncertainties in Atmospheric River Climatology. Journal of Geophysical Research: Atmospheres, 124, https://doi.org/10.1029/2019JD030936.