 |
| Titel |
Comparison of mixed layer heights from airborne high spectral resolution lidar, ground-based measurements, and the WRF-Chem model during CalNex and CARES |
| VerfasserIn |
A. J. Scarino, M. D. Obland, J. D. Fast, S. P. Burton, R. A. Ferrare, C. A. Hostetler, L. K. Berg, B. Lefer, C. Haman, J. W. Hair, R. R. Rogers, C. Butler, A. L. Cook, D. B. Harper |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 11 ; Nr. 14, no. 11 (2014-06-05), S.5547-5560 |
| Datensatznummer |
250118773
|
| Publikation (Nr.) |
 copernicus.org/acp-14-5547-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| The California Research at the Nexus of Air Quality and Climate Change
(CalNex) and Carbonaceous Aerosol and Radiative Effects Study (CARES) field
campaigns during May and June 2010 provided a data set appropriate for
studying the structure of the atmospheric boundary layer (BL). The NASA
Langley Research Center (LaRC) airborne high spectral resolution lidar (HSRL)
was deployed to California onboard the NASA LaRC B-200 aircraft to aid in
characterizing aerosol properties during these two field campaigns.
Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm),
and depolarization (532 and 1064 nm) profiles during 31 flights, many in
coordination with other research aircraft and ground sites, constitute a
diverse data set for use in characterizing the spatial and temporal
distribution of aerosols, as well as the depth and variability of the daytime
mixed layer (ML) height. The paper describes the modified Haar wavelet
covariance transform method used to derive the ML heights from HSRL
backscatter profiles. HSRL ML heights are validated using ML heights derived
from two radiosonde profile sites during CARES. Comparisons between ML
heights from HSRL and a Vaisala ceilometer operated during CalNex were used
to evaluate the representativeness of a fixed measurement over a larger
region. In the Los Angeles basin, comparisons of ML heights derived from HSRL
measurements and ML heights derived from the ceilometer result in a very good
agreement (mean bias difference of 10 m and correlation coefficient of 0.89)
up to 30 km away from the ceilometer site, but are essentially uncorrelated
for larger distances, indicating that the spatial variability of the ML
height is significant over these distances and not necessarily well captured
by limited ground stations. The HSRL ML heights are also used to evaluate the
performance in simulating the temporal and spatial variability of ML heights
from the Weather Research and Forecasting Chemistry (WRF-Chem) community
model. When compared to aerosol ML heights from HSRL, thermodynamic ML
heights from WRF-Chem were underpredicted in the CalNex and CARES regions,
shown by a bias difference value of −157 m and −29 m, respectively.
Better agreement over the Central Valley than in mountainous regions suggests
that some variability in the ML height is not well captured at the 4 km grid
resolution of the model. A small but significant number of cases have poor
agreement when WRF-Chem consistently overestimates the ML height in the late
afternoon. Additional comparisons with WRF-Chem aerosol mixed layer heights
show no significant improvement over thermodynamic ML heights, confirming
that any differences between measurement and model are not due to the
methodology of ML height determination. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|