The Andes Cordillera, which runs the length of South America and rises up to 5,000 m MSL within 200 km of the Pacific coast, dramatically influences the distribution of winter precipitation and snowpack over Chile and Argentina. The study of orographic precipitation processes, particularly along the western slopes of the Andes, is important to improve forecasts of severe flooding and snowpack in a region that depends on snowmelt for water resources. While orographic effects have been investigated on synoptic scales in the Andes, the lack of operational radar coverage and high-elevation, long-term precipitation records have, before the present study, precluded an in-depth investigation into the mesoscale and microphysical processes that affect the distribution of precipitation in the region.
This dataset was collected during the Chilean Orographic and Mesoscale Precipitation Study (ChOMPS), which, from May-October 2016, investigated the evolution of precipitation amounts, dropsize distribution, and the vertical profile of radar echoes along an east-west transect that stretched from the Pacific coast to the windward slope of the Andes. The transect, at ~36°S, was made up of a coastal site upstream of the coastal mountain range (Concepción), a central valley site (Chillán), and a mountain site (Las Trancas). Instrumentation along the transect included three vertically pointing Micro-Rain-Radars, two Parsivel Disdrometers, and several meteorological stations.
The dataset documents the evolution of Doppler velocity and reflectivity profiles with inland extent during early, middle, and late storm sectors. Additionally, the transect provides a season-long record of the inland evolution of melting layer height as well as the prevalence and structure of shallow non-brightband rain and the characteristics of its inland penetration to the central valley. This dataset, the first of its kind in the Chilean Andes, provides unique insight into mesoscale and orographic precipitation processes that also have applicability to the west coast of the United States and other mountainous regions.
Weather-related research often requires synthesizing vast amounts of data that need archival solutions that are both economical and viable during and past the lifetime of the project. Public cloud computing services (e.g., from Amazon, Microsoft, or Google) or private clouds managed by research institutions are providing object data storage systems appropriate for long-term archives of such large geophysical data sets. , Current Status:
Our research group no longer needs to maintain archives of High Resolution Rapid Refresh (HRRR) model output at the University of Utah since complete publicly-accessible archives of HRRR model output are now available from the Google Cloud Platform and Amazon Web Services (AWS) as part of the NOAA Open Data Program.
Google and AWS store the HRRR model output in GRIB2 format, a file type that efficiently stores hundreds of two-dimensional variable fields for a single valid time. Despite the highly compressible nature of GRIB2 files, they are often on the order of several hundred MB each, making high-volume input/output applications challenging due to the memory and compute resources needed to parse these files.
With support from the Amazon Sustainability Data Initiative, our group is now creating and maintaining HRRR model output in an optimized format, Zarr, in a publicly-accessible S3 bucket- hrrrzarr. HRRR-Zarr contains sets for each model run of analysis and forecast files sectioned into 96 small chunks for every variable. The structure of the HRRR-Zarr files are designed to allow users the flexibility to access only the data they need through selecting subdomains and parameters of interest without the overhead that comes from accessing numerous GRIB2 files.
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History:
This effort began in 2015 to illustrate the use of a private cloud object store developed by the Center for High Performance Computing (CHPC) at the University of Utah. We began archiving thousands of two-dimensional gridded fields (each one containing over 1.9 million values over the contiguous United States) from the High-Resolution Rapid Refresh (HRRR) data assimilation and forecast modeling system. The archive has been used for retrospective analyses of meteorological conditions during high-impact weather events, assessing the accuracy of the HRRR forecasts, and providing initial and boundary conditions for research simulations. The archive has been accessible interactively and through automated download procedures for researchers at other institutions that can be tailored by the user to extract individual two-dimensional grids from within the highly compressed files. Over a thousand users have voluntarily registered to use the HRRR archive at the University of Utah.
Our archive has grown to over 130 Tbytes of model output but we no longer need to continue that effort since the GRIB2 files are available now via Google and AWS. As mentioned above, we now provide much of the same information in an alternative format that is appropriate particularly for machine-learning applications.