aeolus: esa’s wind lidar missionearth.esa.int/workshops/atmos2009/participants/580/... · • the...

Atmospheric Science Conference, Barcelona, Spain 7-11 September 2009

Aeolus: ESA’s Wind Lidar Mission

* E. Andersson / ECMWF, A. Dabas / Météo France, P. Flamant / LMD, M. Hardesty / NOAA,E. Källén / MISU, D. Offiler / UKMO, O. Reitebuch / DLR, L.-P. Riishøjgaard / NASA-

GSFC/GMAO, H. Schyberg / met.no, A. Stoffelen / KNMI, M. Vaughan,W. Wergen / DWD, J. Yoe / NOAA

Paul Ingmann, Anne Grete Straume, ESA/ESTEC

and the members of the Aeolus Mission Advisory Group*


Overview

– The Aeolus Mission– Mission preparatory activities– Conclusions


Why launch a space-based wind lidar?

Global Observing System (GOS)• Radiosonde, pilots and soundings (BUT NH continents dominate)• Aircraft data (BUT NH densely populated areas dominate)• Satellite soundings of temperature and humidity from Polar orbiting satellites

(BUT mass information, indirect measure of large-scale phenomenon wind outside the tropics through geostrophical balance)

• Atmospheric motion vectors (BUT only in the presence of clouds)

Maximum possiblecontribution of presentday observing systemsto useful forecast length(hours).The figure is based on a subjectiveevaluation of NWP based forecastsystems taken from WMO/TD No 1228,2004

Need for homogeneous global direct measurements of wind profiles


Aeolus objectives and requirements

Scientific objectivesImprove understanding of

– Global atmospheric dynamics/transport– Global cycling of energy, water, aerosols, chemicals through the

improvements of model dynamics

How are they achieved?– Improved analysis of the atmospheric state to provide a more complete

(three-dimensional) picture of the dynamical variables

Benefits– Better initial conditions for weather forecasting– Improved parameterisation of atmospheric processes in models– Advanced climate and atmospheric flow modelling

Demonstrate the capabilities of space-based high spectral resolution Doppler Wind LIDARs for global wind profiling and its potential for operational use


Observational Requirements PBL Troposph. Stratosph.

Vertical Domain [km] 0-2 2-16 16-20

Vertical Resolution [km] 0.5 1.0 2.0

Horizontal Domain global

Number of Profiles [hour-1] 100

Profile Separation [km] < 200

Horizontal Integration Length [km] 50

Accuracy (HLOS Component) [m/s] 2 2-3 3-5

Timeliness [hour] 3

Length of Observational Data Set [yr] 3

Accuracy most importantNRT delivery required for use in NWP


(ALADIN)

Measurement Concept

The wind profile measurements are derived from the Doppler shifted signals that are back-scattered by aerosols andmolecules along the lidar line-of-sight (LOS)


Aeolus Measurement Baseline

UV lidar (355 nm) with both a molecular and a particle backscatter receiver (High Spectral Resolution)

Horizontal LOS wind profiles (approx. zonal) from surface to ~30 km with resolution varying from 0.5 to 2 km


Aeolus Spin-off Products

• Cloud profile and cloud cover– Cloud top heights and multi-layer clouds– Optical depth– Cloud type

• Aerosols– Stratification– Optical depth– Aerosol type

• Measure of wind variability e.g. caused by clear-air turbulence

• Validation of products from other satellites


Scientific Issues Addressed - Wind

• The usefulness of LOS winds vs. wind vectors for NWP

• Mission impact on NWP

• Vertical and horizontal error correlations

• The yield, accuracy and impact of simulated ADM-Aeolus data in an operational NWP set-up

• The importance of LOS winds and the Aeolus atmospheric sampling strategy for assimilating of the tropical dynamics

• Impact of ADM-Aeolus on predictive skills of mid-latitude high-impact weather systems

• CALIPSO – ADM-Aeolus – EarthCARE long-term atmospheric optical properties database


Operational NWP

• Main impact areas:– Jet streams over the oceans– In the lower troposphere, e.g. western parts of the North Pacific and North

Atlantic oceans, provided large enough cloud gaps– Tropics

Yield, accuracy and impact of simulated Aeolus wind measurements in NWP

___ : Control ensemble- - - : DWL added. . . : radiosondes/wind-profilers removed

Pre

ssur

e (h

Pa)

u (m/s)

Courtesy D. Tan, ecmwf

Tropics


Further pre-launch activities

– Data processing: from Level 0 (raw data), Level 1B (calibrated wind profiles), Level 2A (cloud and aerosol products), Level 2B (scene classified temperature and pressure corrected wind profiles), to Level 2c (assimilated wind products)

– Pre-launch campaigns

– Vertical sampling strategy for the various data applications (e.g. NWP vs. Stratosphere)

– Preparation of post-launch calibration and validation (CAL/VAL) activities


L2B wind retrieval algorithm

• Product: – Profiles of horizontal line-of-sight winds corrected for

atmospheric effects like temperature and pressure effects, classification according to atmospheric scene, quality control, etc.

• First version has been successfully tested for a large range of atmospheric conditions

• Refinements will be done using an extensive simulated Aeolus observation database

• Software is portable to a range of platforms and will be freely available


CampaignsOctober, 2006 1st and 2nd ground-based campaigns with the ALADIN airborne July, 2007 demonstrator (A2D) at the Lindenberg atmospheric observatory (DWD)

9 – 29 Nov 2007 1st airborne campaignTarget area: Middle Europe and Mediterranean Sea5 flights during 15 days with Falcon aircraftPayload: A2D and 2-µm wind lidar and flights over ground observations

27 Nov - 18 Dec 2008 2nd airborne campaignTarget area: Middle Europe and ocean7 flights during 11 days with Falcon aircraftPayload: A2D and 2-µm wind lidar and flights over ground observations

14 Sept – 2 Oct 2009 3rd airborne campaignTarget area: North-West Atlantic 31 flight hours during 18 days, on-site around Iceland 20 h for 4-5 flightsObjectives: 1) analysis of calibration methods and systematic errors -> land and

ice/snow2) observations of high wind speeds and strong wind shear3) sea-surface reflectance for high sea surface winds4) observations of air-masses with low aerosol content5) cloudiness and measurement coverage over developing low pressure

systems


CAL/VAL activities

• Call for Announcement of Opportunities (AOs) including validation issued 2007

• Areas covered by validation AOs– Validation using satellite, airborne or ground-based

experiments providing independent measurements of wind profiles, clouds and aerosols;

– Experiments to assess accuracy, resolution, and stability of the Aeolus instrument ALADIN (Atmospheric Laser Doppler Lidar Instrument);

– Assessment and validation of the Aeolus retrieval and processing


Status of the Aeolus program

• The platform will be completed in 2009 (except from instrument interface part)

• The ALADIN subsystems have all been delivered and qualified on subsystem level

• The transmitter laser is the most challenging for the qualification– The laser diode stacks have successfully completed their qualification testing– Amplifiers have successfully passed the first stability tests– All optical components of the transmitter laser and optical path have been

qualified for the high intensities over the 3-year lifetime

• Thermal vacuum qualification of the Power Laser Head is on-going

• This remaining critical step to achieve a stable laser for vacuum operation is expected to be completed in the near future

• Scheduled launch: autumn 2011


ADM-Aeolus Brochure (left) and Science report (right)

Available at http://www.esa.int/esaLP/LPadmaeolus.html


• Accurate wind profile observations are needed to improve Numerical Weather Prediction, climate modelling and climate analysis

• A feasible concept for a DWL demonstrator has been developed andwill be implemented as the second Earth Explorer Core Mission

• Activities related to science, ground segment development and campaigns are being performed in parallel to the technical activities

• The full science benefit can only be estimated at present

• Launch date: 2011

http: www.esa.int/livingplanet

Conclusions


End presentation


Earth Explorers Research Driven(Core and Opportunity)

Living Planet Programme

Earthnet

Earth WatchService Driven(EUMETSAT and GMES)

ERS & ENVISAT Missions

Earth Observation Activities of ESA

WEB portal with scientific and technical information on ESA EO activities and Third Party Missions

PI6

PI6 No need to show this I guessPaul Ingmann, 12/08/2009


Core

Opportunity

2005 2006 2007 2008 2009 2010 2011 2012

EarthCARECloud, Aerosols & Radiation Explorer

Cryosat 1 & 2 Sea Ice thickness and Ice sheet topography

SMOSSoil Moisture and Ocean Salinity

Swarm

Geomagnetic field survey

GOCEGravity Field and Steady State Ocean Circulation Explorer

ADM-AeolusAtmospheric Dynamics Mission

Earth Explorer missionsPI7

PI7 no need to show - would also require some updatesPaul Ingmann, 12/08/2009


Background – ADM-Aeolus• First concepts: Doppler Wind Lidar (DWL)

working group (1989)• Conceptual DWL mission: 1996• Selected 1999 as second Earth Explorer Core

mission for implementation• Technical predevelopment: 2000 to 2002• Phase C/D started in October 2003• Critical Design Review completed in Sept 2005• Launch planned for 2011


Example of Aeolus sampling

Example of retrieved aerosol backscatter from a Lidar In-space Technology Experiment (LITE) scene. Over-plotted white boxes: baseline Aeolus data sampling.Some artefacts of the retrieval are visible especially inside and below the clouds.

Courtesy: KNMIThe raw data were obtained fromthe NASA Langley Research CenterAtmospheric Science Data Center.

-8.6

-4.5

aero

sol b

acks

catte

r


Aeolus Performance Prediction


The contribution of Aeolus to long-term aerosol and cloud optical properties database (IfT,

Leipzig / D)• Objective

– The potential of Aeolus to measure optical properties of aerosol and clouds based on end-to-end simulation studies

• Conclusions– Aeolus is able to provide global sets of trustworthy height-profiles of

backscatter and extinction coefficients, and extinction-to-backscatter (lidar) ratios

– Aeolus can contribute to a long-term dataset of aerosol and cloud optical properties from CALIPSO (launch: April 2006) to EarthCARE (operational until: 2015)


– Assess the added value of a space-borne DWL in NWP to enhance the predictive skill of high-impact weather systems with a focus on Northern Hemisphere extra-tropics

– Define capability requirements for Aeolus follow-on system– Example of possible sampling scenarios:

– ADM-Aeolus is capable of resolving part of the NH extra-tropical analysis error structures in data sparse areas, improving the forecast after 2 days and beyond

– Measuring wind vector profiles (dual perspective) gives a 50% forecast improvement (NH average) with respect to Aeolus

– Two Aeolus in orbit (tandem scenario) gives an (NH) averaged forecast improvement of 70%

PIEW study (KNMI / NL)

Dual perspectiveADM-Aeolus tandemADM-Aeolus

CourtesyN. Žagar

Dual inclination

PI8

PI8 not essentialPaul Ingmann, 12/08/2009


Aeolus optical properties retrieval

• Example of High Spectral Resolution Lidar(HSRL) solutions (red) of the particle backscatter coefficient, extinction coefficient,and the corresponding extinction–to–backscatter ratio (lidar ratio) for a lofted dust case (upper plots) and a forest fire smoke case (lower plots). Assumption: perfect knowledge of instrument and atmospheric input parameters.• Horizontal lines: top of the layers with vertical resolution of 500 m (3.5–km height) and 1000 m (14.5–km height).• The thin grey profiles: true profiles of optical properties used in the ALADIN signal simulation.

Courtesy A. Ansmann


EUMETSAT study on the impact of Aeolus sampling scenarios for the modeling of Tropical dynamics

(UL / SLO in cooperation with KNMI / NL and MISU / S)

• Weak balance relationships in the tropics: Wind measurements arecrucial for the reduction of uncertainties in the tropical analysis fields.

• A second satellite can reduce the analysis error by an additional 50% w.r.t. Aeolus. In the case of a poor background-error, orthogonal observations of wind vectors are preferable.

• The dual-inclination scenario provides on average best scores due to more spatial coverage and by measuring both wind components.

• Weak mass-wind coupling: 4D-Var cannot extract information on the meridional wind component from the Tandem-Aeolus winds to the same extent as in the extra-tropics.

PI9

PI9 not essentialPaul Ingmann, 12/08/2009


14 Sept – 2 Oct 2009 Third airborne campaign:

15 days Falcon, 31 flight hours: 1 test flight with 3 h,2 transfer with 8 h, on-site in Iceland 20 h for 4-5 flights

Proposed objectives (tbd):

1.) Obtain data set for sea-surface reflectance for high seasurface winds

2.) In-flight response calibration with nadir pointing over ice, e.g. Greenland

3.) Observations of jet stream with high wind speeds and high vertical and horizontal wind shear

4.) Observations of marine air-masses with very low aerosol content

Campaigns in 2009

May-August A2D observations at DLR from ground

2-µm DWL

A2D

transmit pathreceive path


Example of L2B scene classification

Schematic representation of test scenariowith three overlapping cloud layers. L2B classification of the test scenario.

Red/green/blacks indicates that the measurementrange-gate is classified as clear/cloudy/not used.

BRC1 BRC2 BRC3 BRC4

Clear C

loud

2 C

loud

3 C

loud

4 C

loud

5

Cloud1

Boundary layer background aerosols


The Lindenberg column

Measurements: vertical profiles of wind, temperature, precipitation, water vapour, liquid water, microphysical properties of clouds, cloud cover, cloud base, ozone profiles, latent and sensible heat, radiation.

aeolus: esa’s wind lidar missionearth.esa.int/workshops/atmos2009/participants/580/... · • the...

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