Assimilation of lidar planetary boundary layer height observations
<p>Lidar backscatter and wind retrievals of the planetary boundary layer height (PBLH) are assimilated into 22-hourly forecasts from the NASA Unified – Weather and Research Forecast (NU-WRF) model during the Plains Elevated Convection at Night (PECAN) campaign on 11 July 2015 in Greensburg, Ka...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-02-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/14/1099/2021/amt-14-1099-2021.pdf |
| Summary: | <p>Lidar backscatter and wind retrievals of the planetary boundary layer height (PBLH) are assimilated into 22-hourly forecasts from the
NASA Unified – Weather and
Research Forecast (NU-WRF) model during the Plains Elevated Convection at Night (PECAN) campaign on 11 July 2015 in Greensburg,
Kansas, using error statistics collected from the model profiles to compute the necessary covariance matrices. Two separate
forecast runs using different PBL physics schemes were employed, and comparisons with six independent radiosonde profiles were made
for each run. Both of the forecast runs accurately predicted the PBLH and the state variable profiles within the planetary boundary layer
during the early morning, and the assimilation had a small impact during this time.
In the late afternoon, the forecast runs showed decreased accuracy as the convective boundary layer developed.
However, assimilation of
the Doppler lidar PBLH observations was
found to improve the temperature and <span class="inline-formula"><i>V</i></span>-velocity profiles relative to independent radiosonde profiles. Water vapor
was overcorrected, leading to increased differences with independent data. Errors in the <span class="inline-formula"><i>U</i></span> velocity were made slightly larger.
The computed forecast error covariances between the PBLH and state variables
were found to rise in the late afternoon, leading to the larger improvements in the afternoon.
This work represents the first effort to assimilate PBLH into forecast states using ensemble methods.</p> |
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| ISSN: | 1867-1381 1867-8548 |