ALADIN laser frequency stability and its impact on the Aeolus wind error
<p>The acquisition of atmospheric wind profiles on a global scale was realized by the launch of the Aeolus satellite, carrying the unique Atmospheric LAser Doppler INstrument (ALADIN), the first Doppler wind lidar in space. One major component of ALADIN is its high-power, ultraviolet (UV) lase...
Main Authors: | , , , , , , , , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2021-09-01
|
Series: | Atmospheric Measurement Techniques |
Online Access: | https://amt.copernicus.org/articles/14/6305/2021/amt-14-6305-2021.pdf |
id |
doaj-d7f1a02a4cc641f7921850406fe10976 |
---|---|
record_format |
Article |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
O. Lux C. Lemmerz F. Weiler T. Kanitz D. Wernham G. Rodrigues A. Hyslop O. Lecrenier P. McGoldrick F. Fabre P. Bravetti T. Parrinello O. Reitebuch |
spellingShingle |
O. Lux C. Lemmerz F. Weiler T. Kanitz D. Wernham G. Rodrigues A. Hyslop O. Lecrenier P. McGoldrick F. Fabre P. Bravetti T. Parrinello O. Reitebuch ALADIN laser frequency stability and its impact on the Aeolus wind error Atmospheric Measurement Techniques |
author_facet |
O. Lux C. Lemmerz F. Weiler T. Kanitz D. Wernham G. Rodrigues A. Hyslop O. Lecrenier P. McGoldrick F. Fabre P. Bravetti T. Parrinello O. Reitebuch |
author_sort |
O. Lux |
title |
ALADIN laser frequency stability and its impact on the Aeolus wind error |
title_short |
ALADIN laser frequency stability and its impact on the Aeolus wind error |
title_full |
ALADIN laser frequency stability and its impact on the Aeolus wind error |
title_fullStr |
ALADIN laser frequency stability and its impact on the Aeolus wind error |
title_full_unstemmed |
ALADIN laser frequency stability and its impact on the Aeolus wind error |
title_sort |
aladin laser frequency stability and its impact on the aeolus wind error |
publisher |
Copernicus Publications |
series |
Atmospheric Measurement Techniques |
issn |
1867-1381 1867-8548 |
publishDate |
2021-09-01 |
description |
<p>The acquisition of atmospheric wind profiles on a global
scale was realized by the launch of the Aeolus satellite, carrying the
unique Atmospheric LAser Doppler INstrument (ALADIN), the first Doppler wind lidar in space. One major component of ALADIN is its high-power, ultraviolet
(UV) laser transmitter, which is based on an injection-seeded,
frequency-tripled Nd:YAG laser and fulfills a set of demanding requirements
in terms of pulse energy, pulse length, repetition rate, and spatial
and spectral beam properties. In particular, the frequency stability of the
laser emission is an essential parameter which determines the performance of
the lidar instrument as the Doppler frequency shifts to be detected are on
the order of 10<span class="inline-formula"><sup>8</sup></span> smaller than the frequency of the emitted UV light.
This article reports the assessment of the ALADIN laser frequency stability
and its influence on the quality of the Aeolus wind data. Excellent
frequency stability with pulse-to-pulse variations of about 10 MHz (root
mean square) is evident for over more than 2 years of operations in space
despite the permanent occurrence of short periods with significantly
enhanced frequency noise (<span class="inline-formula">></span> 30 MHz). The latter were found to
coincide with specific rotation speeds of the satellite's reaction wheels,
suggesting that the root cause are micro-vibrations that deteriorate the
laser stability on timescales of a few tens of seconds. Analysis of the
Aeolus wind error with respect to European
Centre for Medium-Range Weather Forecasts (ECMWF) model winds shows that the
temporally degraded frequency stability of the ALADIN laser transmitter has
only a minor influence on the wind data quality on a global scale, which is
primarily due to the small percentage of wind measurements for which the
frequency fluctuations are considerably enhanced. Hence, although the Mie
wind bias is increased by 0.3 m s<span class="inline-formula"><sup>−1</sup></span> at times when the
frequency stability is worse than 20 MHz, the small contribution of 4 %
from all Mie wind results renders this effect insignificant
(<span class="inline-formula"><</span> 0.1 m s<span class="inline-formula"><sup>−1</sup></span>) when all winds are considered. The impact on the
Rayleigh wind bias is negligible even at high frequency noise. Similar
results are demonstrated for the apparent speed of the ground returns that
are measured with the Mie and Rayleigh channel of the ALADIN receiver. Here, the application of a frequency stability threshold that filters out wind observations with variations larger than 20 or 10 MHz improves the accuracy of the Mie and Rayleigh ground velocities by only 0.05
and 0.10 m s<span class="inline-formula"><sup>−1</sup></span>, respectively, however at the expense of
useful ground data.</p> |
url |
https://amt.copernicus.org/articles/14/6305/2021/amt-14-6305-2021.pdf |
work_keys_str_mv |
AT olux aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT clemmerz aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT fweiler aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT tkanitz aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT dwernham aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT grodrigues aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT ahyslop aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT olecrenier aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT pmcgoldrick aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT ffabre aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT pbravetti aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT tparrinello aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror AT oreitebuch aladinlaserfrequencystabilityanditsimpactontheaeoluswinderror |
_version_ |
1716866129472782336 |
spelling |
doaj-d7f1a02a4cc641f7921850406fe109762021-09-28T13:20:05ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482021-09-01146305633310.5194/amt-14-6305-2021ALADIN laser frequency stability and its impact on the Aeolus wind errorO. Lux0C. Lemmerz1F. Weiler2T. Kanitz3D. Wernham4G. Rodrigues5A. Hyslop6O. Lecrenier7P. McGoldrick8F. Fabre9P. Bravetti10T. Parrinello11O. Reitebuch12Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Oberpfaffenhofen, GermanyInstitut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Oberpfaffenhofen, GermanyInstitut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Oberpfaffenhofen, GermanyEuropean Space Research and Technology Centre, European Space Agency, Noordwijk, 2201 AZ, the NetherlandsEuropean Space Research and Technology Centre, European Space Agency, Noordwijk, 2201 AZ, the NetherlandsEuropean Space Research and Technology Centre, European Space Agency, Noordwijk, 2201 AZ, the NetherlandsVitrociset (a Leonardo company), for ESA, Noordwijk, 2201 DK, the NetherlandsAirbus Defence and Space (Toulouse), Rue des Cosmonautes, 31400 Toulouse, Franceformerly at: Airbus Defence and Space (Stevenage), Gunnels Wood Rd, Stevenage SG1 2AS, United KingdomLes Myriades SAS, Consultancy for Optical Systems, 2 Rue Temponières, 31000 Toulouse, FranceAirbus Italia S.p.A., Via dei Luxardo, 22-24, 00156 Rome, ItalyEuropean Space Research Institute, European Space Agency, 00044 Frascati RM, ItalyInstitut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, 82234 Oberpfaffenhofen, Germany<p>The acquisition of atmospheric wind profiles on a global scale was realized by the launch of the Aeolus satellite, carrying the unique Atmospheric LAser Doppler INstrument (ALADIN), the first Doppler wind lidar in space. One major component of ALADIN is its high-power, ultraviolet (UV) laser transmitter, which is based on an injection-seeded, frequency-tripled Nd:YAG laser and fulfills a set of demanding requirements in terms of pulse energy, pulse length, repetition rate, and spatial and spectral beam properties. In particular, the frequency stability of the laser emission is an essential parameter which determines the performance of the lidar instrument as the Doppler frequency shifts to be detected are on the order of 10<span class="inline-formula"><sup>8</sup></span> smaller than the frequency of the emitted UV light. This article reports the assessment of the ALADIN laser frequency stability and its influence on the quality of the Aeolus wind data. Excellent frequency stability with pulse-to-pulse variations of about 10 MHz (root mean square) is evident for over more than 2 years of operations in space despite the permanent occurrence of short periods with significantly enhanced frequency noise (<span class="inline-formula">></span> 30 MHz). The latter were found to coincide with specific rotation speeds of the satellite's reaction wheels, suggesting that the root cause are micro-vibrations that deteriorate the laser stability on timescales of a few tens of seconds. Analysis of the Aeolus wind error with respect to European Centre for Medium-Range Weather Forecasts (ECMWF) model winds shows that the temporally degraded frequency stability of the ALADIN laser transmitter has only a minor influence on the wind data quality on a global scale, which is primarily due to the small percentage of wind measurements for which the frequency fluctuations are considerably enhanced. Hence, although the Mie wind bias is increased by 0.3 m s<span class="inline-formula"><sup>−1</sup></span> at times when the frequency stability is worse than 20 MHz, the small contribution of 4 % from all Mie wind results renders this effect insignificant (<span class="inline-formula"><</span> 0.1 m s<span class="inline-formula"><sup>−1</sup></span>) when all winds are considered. The impact on the Rayleigh wind bias is negligible even at high frequency noise. Similar results are demonstrated for the apparent speed of the ground returns that are measured with the Mie and Rayleigh channel of the ALADIN receiver. Here, the application of a frequency stability threshold that filters out wind observations with variations larger than 20 or 10 MHz improves the accuracy of the Mie and Rayleigh ground velocities by only 0.05 and 0.10 m s<span class="inline-formula"><sup>−1</sup></span>, respectively, however at the expense of useful ground data.</p>https://amt.copernicus.org/articles/14/6305/2021/amt-14-6305-2021.pdf |