Correction of wind bias for the lidar on board Aeolus using telescope temperatures
<p>The European Space Agency (ESA) Earth Explorer satellite Aeolus provides continuous profiles of the horizontal line-of-sight wind component globally from space. It was successfully launched in August 2018 with the goal to improve numerical weather prediction (NWP). Aeolus data have already...
Guardado en:
| Autores principales: | , , , , , , , |
|---|---|
| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
|
| Materias: | |
| Acceso en línea: | https://doaj.org/article/e3054c6892474c109eb92fedae1a263a |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| Sumario: | <p>The European Space Agency (ESA) Earth Explorer satellite Aeolus provides continuous profiles of the
horizontal line-of-sight wind component globally from space. It was
successfully launched in August 2018 with the goal to improve numerical
weather prediction (NWP). Aeolus data have already been successfully
assimilated into several NWP models and have already helped to significantly
improve the quality of weather forecasts. To achieve this major milestone
the identification and correction of several systematic error sources were
necessary. One of them is related to small fluctuations of the temperatures
across the 1.5 m diameter primary mirror of the telescope which cause
varying wind biases along the orbit of up to 8 m s<span class="inline-formula"><sup>−1</sup></span>. This paper presents a
detailed overview of the influence of the telescope temperature variations
on the Aeolus wind products and describes the approach to correct for this
systematic error source in the operational near-real-time (NRT) processing.
It was shown that the telescope temperature variations along the orbit are
due to changes in the top-of-atmosphere reflected shortwave and outgoing
longwave radiation of the Earth and the related response of the telescope's
thermal control system. To correct for this effect ECMWF model-equivalent
winds are used as a reference to describe the wind bias in a multiple linear
regression model as a function of various temperature sensors located on the
primary telescope mirror. This correction scheme has been in operational use
at ECMWF since April 2020 and is capable of reducing a large part of the
telescope-induced wind bias. In cases where the influence of the temperature
variations is particularly strong it was shown that the bias correction can
improve the orbital bias variation by up to 53 %. Moreover, it was
demonstrated that the approach of using ECMWF model-equivalent winds is
justified by the fact that the global bias of model <span class="inline-formula"><i>u</i></span>-component winds with respect to
radiosondes is smaller than 0.3 m s<span class="inline-formula"><sup>−1</sup></span>. Furthermore, this paper presents the
alternative of using Aeolus ground return winds which serve as a zero-wind
reference in the multiple linear regression model. The results show that the
approach based on ground return winds only performs 10.8 % worse than the
ECMWF model-based approach and thus has a good potential for future
applications for upcoming reprocessing campaigns or even in the NRT
processing of Aeolus wind products.</p> |
|---|