Skip to main content
U.S. flag

An official website of the United States government

Dot Gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

HTTPS

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Development and Testing of 3d- and 4D-ENVAR Subhourly Data Assimilation In The HRRR

Abstract

The current operational configuration of the 3-km High-Resolution Rapid Refresh (HRRR) features an hourly update cycle based on a downscaled RAP initialization and a one-hour pre-forecast. In an effort to take advantage of sub-hour observational data, testing of 15-minute update cycles during the one-hour pre-forecast was conducted using both 3D- and 4D-EnVar. Initial findings indicate that on average, both 3D- and 4D-EnVar result in a closer fit to the obs (lower RMSE and bias) when compared to hourly 3D-EnVar for traditional verification metrics at analysis time. For 1-, 3-, and 6-hr forecasts, the sub-hourly DA provides an overall neutral impact. However, analysis of radar reflectivity during the free forecast indicates a potential qualitative improvement of placement and intensity of small-scale precipitation features for the sub-hourly runs, in particular for the 4D-EnVar simulations. In addition, a comparison of spread was conducted between the GFS ensemble, currently used in the 3DEnVar operational HRRR DA system, and a prototype 3-km WRF-based ensemble. Much more detail and evolution in mesoscale features was apparent in the 3-km WRF-based ensemble between forecast hours, suggesting that its use in DA could greatly impact forecast results. Further analysis will focus on assessing changes within the three backgrounds used in 4D-EnVar to illustrate how this evolution impacts the final analysis and forecast.

Article / Publication Data
Active/Online
YES
Available Metadata
Fiscal Year
Published On
January 01, 2018
Type
Event

This publication was presented at the following:

Title
AMS 98th Annual meeting - 2018
Sponsor
American Meteorological Society
Type
Conference presentation

Institutions

Not available

Authors

Authors who have authored or contributed to this publication.

Not available