Morgane

MORGANE: Maïdo ObservatoRy Gaz and Aerosols Ndacc Experiment - May 2015

BE CAREFUL: all figures are preliminary results not yet validated by the Principal Investigators

NRT : Near Real Time : data issue of automatic program, no validated by PI

Introduction

Objectives

The objectives of the MORGANE experiment are threefold:

a blind test intercomparison between lidars (vertical profiles for temperature, ozone, aerosols and water vapour) from OPAR (Observatoire de Physique de l’Atmosphère à La Réunion) and from NASA/GSFC mobile laboratory in view of the labellisation of OPAR lidars in NDACC (Network for Detection of Atmospheric Composition Changes).
night- and day-time radiosoundings (vertical profiles for meteorological parameters, ozone, aerosols and water vapour) with technical objectives in the NDACC, GRUAN (GCOS Reference Upper Air Network), and ACTRIS-2 (Aerosols, Clouds, and Trace Gases Research InfraStructure) programms: providing highly accurate measurements for atmospheric radiosounding profiles, calibration and validation of lidar profiles.
research studies on the composition and on the dynamics of the tropical UTLS (upper troposphere and lower stratosphere) in the southern hemisphere.

Participants include the following research laboratories: UMS/OSU-R and LACy (CNRS & Université de La Réunion), LATMOS and SIRTA (IPSL, Paris, France), LaMP (OPGC), LPC2E (CNRS and Université d’Orléans), NASA/GSFC (Greenbelt, USA), DWD (Lindenberg, Germany), and ETHZ (Zurich, Swiss).

Schedule

week 18 (april 27 - may 3): technical preparation week #1
week 19 (4 - 10 may): technical preparation week #2
week 20 (11 - 17 may) : blind intercomparison week #1
May 18: New Moon
week 21 (18 - 24 may) : blind intercomparison week #2
week 22 (25 - 29 may) : blind intercomparison week #3

Instruments and Principal Investigators

Lidars :

LIO3S: stratospheric ozone lidar (OPAR) : PI Thierry Portafaix (LACy), Co-I Sophie Godin-Beekmann (LATMOS).
LIO3T : tropospheric ozone & aerosols lidar (OPAR) : PI Valentin Duflot (LACy).
LI1200 : water vapor & temperature lidar (OPAR) : PIs : Philippe Keckhut (LATMOS) (water vapor), Alain Hauchecorne (LATMOS) (temperature), Co-I Valentin Duflot (LACy).
LIAER : ALS450 Léosphère aerosols lidar : PI Valentin Duflot (LACy).
STROZ : stratospheric ozone, temperature, aerosol backscatter and microphysical properties, water vapour (NASA) : PI Tomas McGee (NASA).

Radiosoundings:

M10 (MODEM) : Pression, Temperature, Humidity, Winds, PI Françoise Posny (LACy).
ECC-ozone (+M10) : Pression, Temperature, Humidity, Winds, Ozone, PI Françoise Posny (LACy).
RS41 (VAISALA) : Pression, Temperature, Humidity, Winds, PI R. Dirksen and Susanne Meier (DWD).
RS92 (VAISALA) : Pression, Temperature, Humidity, Winds, PI R. Dirksen (DWD) and J.P. Cammas (UMS).
CFH (+IMET) : Cryogenic Frost Point Hygrometer, Pression, Temperature, Humidity, Winds, PI R. Dirksen (DWD), co-I : S. Evan (LACy).
COBALD : Compact Optical Backscatter AeroloL Detector, PI R. Dirksen (DWD), co-I : S. Evan (LACy), F. Wienhold (ETHZ).
LOAC : Light Optical Particle Counter, PI J.-B. Renard (LPC2E), co-I : N. Bégue (LACy), V. Duverger (LPC2E).

Spectrometers :

2 FTIR (Fourrier Transform Infrared Spectroscopy) at Maïdo observatory and at University, PI Martine de Mazière (IASB).
Infra-red spectrometer, PI Gérard Brognier (LOA).
SAOZ (Système d'Analyse par Observations Zénithales), PI Andrea Pazmino (LATMOS), Co-I Thierry Portafaix (LACy).

GNSS :

GNSS station at Maïdo observatory, PI Jimmy Leclerc De Bellevue (LACy)

Photometers:

Microtops, PI Valentin Duflot (LACy).
ODS (Optical Deph Sensor), PI Jean-Pierre Pommereau (LATMOS).

Installation of NASA's lidars

40 feet container installation

Arrival of the first container at the Maido observatory: August 27, 2014

Some problems during the climbing

Arrival of the container at the observatory

20 feet container installation

Arrival of the second container at the Maido observatory: January 17, 2015

Preliminary tests of NASA's lidars (February - March 2015)

Tom McGee and Grant Sumnicht arrived at La Reunion Island on the 25th of February 2015 and leaved on March 10th, 2015.

Status of the equipment:

- the excimer laser is down

- the YAG laser is OK

- data acquisition computers are down

No lidar acquisition was possible

Technical preparation week 1 (April 29-30)

Arrival of Tom McGee (NASA) and Grant Sumnicht (NASA): April 29, 2015.

Work to fix the NASA excimer laser : not successful

Technical preparation week 2 (4-8 May)

Arrival of Susanne Meier (DWD) and of Jean-Luc Baray (LaMP)

Work to fix the NASA eximer laser: not successful

blind intercomparison week 1 (11-15 May)

Arrivals and departures:

Arrival of Philippe Keckhut (LATMOS) and Alain Sarkissian (LATMOS) the 13/05/2015.
Departure of Philippe Keckhut and Alain Sarkissian the 15/05/2015
Departure of Jean-Luc Baray the 16/05/2015

The MORGANE campagn on Clicanoo : [1]

15/05/2015 : Installation of a telescopic mast

15/05/2015 : group photo

From left to right : Jean-Luçay Felix, Jean-Marc Metzger, Remy Decoupes, Nicolas Marquestaut, Françoise Posny, Philippe Keckhut, Hélène Vérèmes, Valentin Duflot, Jérome Brioude, Guillaume Payen, Stéphanie Evan, Susanne Meier, Jean-Pierre Cammas, Jean-Luc Baray, Grant Sumnicht, Tom McGee, Alain Sarkissian

blind intercomparison week 2 (18-22 May)

Press conference : 19/05/2015

From left to right : Jean-Luçay Felix, Hélène Vérèmes, Grant Sumnicht, Tom McGee, Jean-Marie Flaud, Jean-Pierre Cammas, Thierry Portafaix, Sophie Godin-Beeckmann, Remy Decoupes, Françoise Posny, Alain Hauchecorne, Jean-Marc Metzger, Patrick Hernandez, Guillaume Payen, Thierry Leblanc, Eric Golubic, Stéphanie Evan, Jérome Brioude, Susanne Meier

Status of instruments

Valid on May 21th, 2015

Lidars :

LIO3S (OPAR): stratospheric ozone lidar / Status = OK
LIO3T (OPAR): tropospheric ozone & aerosols lidar / Status = OK
LI1200 (OPAR): water vapor & temperature lidar / Status = OK
LIAER (OPAR): ALS450 Léosphère aerosols lidar / Status = OK
STROZ YAG (NASA): / Status = OK
STROZ EXIMER (NASA)/ Status = DOWN

Radiosoundings:

M10 (MODEM) / Status = OK
ECC-ozone (+M10) / Status = OK
RS41 (VAISALA) / Status = OK
RS92 (VAISALA) / Status = OK
CFH (+IMET) / Status = OK
COBALD / Status = OK
LOAC / Status = OK

Spectrometers :

FTIR (IASB) at Maïdo observatory / Status = DOWN
FTIR (IASB) at University / Status = OK (TCCON + NDACC networks)
Infra-red spectrometer / Status = Re-installation process
SAOZ / Status = OK

GNSS :

GNSS station / Status = OK

Photometers:

Microtops / Status = OK
ODS (Optical Deph Sensor) / Status = OK

Fonctionnement des instruments
	LIO3S	LIO3T	LI1200
5/04	18h26 - 19h44	18h48 - 19h45	18h30 - 19h44
5/05	18h26 - 21h10	17h10 - 18h34	16h13 - 18h26
		19h43 - 21h11
5/06	18h05 - 20h46	16h03 - 20h46	15h55 - 20h45
5/07	13h39 - 15h22	12h46 - 15h34	08h03 - 13h23
			13h29 - 15h33
5/11	18h23 - 21h26	18h43 - 21h28	18h22 - 21h27
5/12	15h35 - 18h26	15h50 - 18h26	15h31 - 21h27
5/13	15h30 - 20h22	15h46 - 20h22	16h09 - 20h22
5/15	19h49 - 22h49	19h00 - 22h49	19h48 - 22h48
5/18	15h49 - 20h20	16h00 - 20h20	16h03 - 20h20
5/19	14h52 - 20h08	15h14 - 19h29	14h48 - 20h09
5/20	15h29 - 19h39	15h35 - 19h40	15h33 - 19h39

Radiosounding observations

May 5, 2015: Daytime Radiosounding with payload RS92 + RS41 + M10 (1/10)

A first balloon has been launched at 1100UTC:

- M10ND: technical problem with the sonde (no data transmission)

- RS92 & RS41: loss of signal between 13 and 21 km altitude

Regular- and GRUAN-processed data. Vaïsala RS92 & RS41

A second balloon with a M10ND sonde has been launched at 1130UTC.

Modem M10ND

May 7, 2015, 1100 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (2/10)

RS92 and RS41 data processed

M10ND data processed

May 7, 2015, 1700 UTC: Nighttime radiosounding with payload RS92 + COBALD

The objective is to capture the ash layer associated with the Calbuco volcanic plume (eruption in Chile, April 22, 2015). The volcanic plume is monitored by satellites (see below an example of METOP/IASI retrievals) and has been observed by OPAR & NASA lidars at about 17 km altitude since May 6th (see lidar section).

METOP/IASI SO2 brightness temperature
06/05/2015

RS92 and COBALD data are processed.

The plot below displays vertical profiles backscatter ratios in red and blue wavelengths from the COBALD data. Peaks at about 19km altitude are associated with the volcanic-origin ash layer. Other peaks at 8 and 9 km altitudes are associated with cirrus clouds.

May 11, 2015, 1100 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (3/10)

Radiosounding data have been processed

May 11, 2015, 1830 UTC: Nighttime radiosounding with payload M10/ECC + RS92 + RS41 (1/4)

First radiosounding with ozone.

The balloon went across the laser beam above the observatory (see photo below). It burst at 32 km altitude.

Vaïsala radiosounding data have been processed.

Modem data are processed.

May 12, 2015, 1200 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (4/10)

RS92 & RS41 Vaïsala radiosounding data have been processed

M10ND radiosounding: technical problem (no data transmission)

May 12, 2015, 1630 UTC: Nighttime radiosounding with payload RS92 + RS41 + M10/ECC + CFH/COBALD/IMET (1/6)

Two problems occurred: 1) Technical problem on CFH soon after launch 2) Lost of signals on all sondes between 12 and 21 km altitude: it is likely due to the masking effect of nearby mountains on data transmission in case of strong westerly subtropical jet (> 45ms-1 this night). Data were transmitted again above 21 km until the ballon burst at 26 km altitude.

RS92/RS41 data have been processed

May 13, 2015: NDACC/SHADOZ radiosounding at Gillot (seal level): payload M10/ECC Ozone

Technical problem on the payload: no data

May 15, 2015, 1300 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (5/10)

RS41 Vaïsala and M10ND radiosoundings: OK, data are being processed

RS92 Vaïsala radiosounding: a new position of antenna + GPS has been tried to test transmission (surelevation of 8m on a mast). The first part of the sounding ends prematuraly due to lack of ground values. The second part of the sounding (separate file) includes the descent after burst, down to 11 km altitude. The premature end of the sounding during the descent has occurred at the same altitude as for the other 2 sondes (RS41 and M10ND) for which antennas weren't surelevated. The conclusion is that there is no gain to surelevate the antennas. We have better to avoid any transmission data risk due to mountain mask in case of to strong westerlies. A software taking account the ascent rate of the balloon, its predicted trajectory and the mountain mask will be used to minimize the risks of premature end of data transmission during the ascent phase of the balloon.

May 15, 2015, 1800 UTC: Nighttime radiosounding with payload RS92 + RS41 + M10/ECC + CFH/COBALD/IMET (2/6)

Whole payload was ok; radiosounding was ok. Data are being processed.

Preliminary intercomparison between stratospheric and tropospheric DIAL ozone lidars (OPAR) and MLS data

Stratospheric ozone tracer from FLEXPART simulation: suggestion of stratospheric intrusions above 10 km altitude

Processed RS92/RS41/CFH/COBALD data:

COBALD shows volcanic ash plume between 17 - 20km

May 18, 2015, 1300 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (6/10)

Payload was ok.

A technical problem arose on the GPS data transmission that was interruped on RS41 sonde. Data were transmitted again above 300 hPa.

Data are being processed.

Processed RS92/RS41 profiles:

May 18, 2015, 1700 UTC: Nighttime Radiosounding with payload RS92 + RS41 + M10/ECC + CFH/COBALD/IMET (3/6)

Processed RS92/RS41/CFH profiles:

M10/ECC data are being processed

May 19, 2015, 0900 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (7/10)

Payload was ok.

Processed RS92/RS41 profiles:

May 19, 2015, 1600 UTC: Nighttime Radiosounding with payload LOAC + M10 (1/1)

Payload was ok. Data are being processed.

May 19, 2015, 1800 UTC: Nighttime Radiosounding with payload RS92 + RS41 + M10/ECC + CFH/COBALD/IMET (4/6)

Payload was ok, except for M10/ECC

Processed RS92/RS41/CFH profiles:

May 20, 2015: NDACC/SHADOZ radiosounding at Gillot (seal level): payload M10/ECC Ozone

May 21, 2015, 1100 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (8/10)

Payload was ok. Data are being processed.

May 21, 2015, 1800 UTC: Nighttime Radiosounding with payload RS92 + RS41 + M10/ECC + CFH/COBALD/IMET (5/6)

Payload was ok. Data are being processed.

May 22, 2015, 1100 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 + CFH/IMET (9/10)

Payload was ok. Data are being processed.

May 22, 2015, 1800 UTC: Nighttime Radiosounding with payload RS92 + RS41 + M10/ECC + CFH/COBALD/IMET (6/6)

Payload was ok. Data are being processed.

May 26, 2015, 1100 UTC: Daytime Radiosounding with payload RS92 + RS41 + M10 (10/10)

Payload was ok, except M10ND sonde (no data transmission). Data are being processed.

Lidars observations

May 4, 2015

Weather : some clouds

Time of measurements for lidars (UTC time) :

LIO3S : 18h26 - 19h44 (78 minutes)
LIO3T : 18h48 - 19h45 (57 minutes)
LI1200 : 18h30 - 19h44 (74 minutes)

Raw data
lio3t
lio3s
li1200

NRT data
lio3s
li1200: profil of the night
li1200: time serie
li1200: backscatter ratio (UTC time)
Bsr20150504 lio3s 2.jpg

lio3s: backscatter ratio, channel 355 low (UTC time)
lio3s: backscatter ratio, channel 355 hight (UTC time)
Bsr20150504 lio3t 4.jpg

lio3t: cloudy sky

May 5, 2015

Weather : clear sky

Work on stratospheric ozone lidar (synchronisation) in the beginning of the night.

Observations :

the LI1200 lidar sees the STROZ lidar and in return STROZ lidar sees the LI1200 lidar
the STROZ lidar does not see the LIO3S lidar
The box of synchronization of OPAR does not seem to work

Time of measurements for lidars (UTC time) :

LIO3S : 18h26 - 21h10 (164 minutes)
LIO3T : 17h10 - 18h34 (84 minutes) and 19h43 - 21h11 (88 minutes)
LI1200 : 16h13 - 18h26 (133 minutes)

For LI1200, between 18h26 and 21h11, lasers worked but we did some tests of synchronization with NASA lidars

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

NRT data
lio3s
li1200: profil of the night
li1200: time serie
li1200: backscatter ratio (UTC time)
lio3s: backscatter ratio, channel 355 low (UTC time)
lio3s: backscatter ratio, channel 355 hight (UTC time)
lio3t: backscatter ratio (UTC time)

Intercomparison between tropospheric and stratospheric ozone lidar of OPAR

NASA GSFC STROZ lidar: raw data

May 6, 2015

Weather : clear sky

Time of measurements for lidars (UTC time) :

LIO3S : 18h05 - 20h46 (161 minutes)
LIO3T : 16h03 - 20h46 (283 minutes)
LI1200 : 15h55 - 20h45 (289 minutes)

Lidars setup :

we have used the box of synchronization of the NASA to synchronize STROZ and LI1200 : no covering
when LIO3S is working, STROZ sees it : covering

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

NRT data
lio3t: Profil between 16h01 - 16h57
lio3t: Profil between 16h01 - 16h57
lio3t: Profil between 16h59 - 17h57
lio3t: Profil between 16h59 - 17h57
lio3t: Profil between 17h59 - 18h56
lio3t: Profil between 17h59 - 18h56
lio3t: Profil between 18h58 - 19h56
lio3t: Profil between 18h58 - 19h56
lio3t: Profil between 19h58 - 20h50
lio3t: Profil between 19h58 - 20h50
lio3t: profil the night
lio3t: profil the night
li1200: backscatter ratio (UTC time)
lio3s: backscatter ratio, channel 355 low (UTC time)
lio3s: backscatter ratio, channel 355 hight (UTC time)
lio3t: backscatter ratio (UTC time)

The dense layer displayed at about 17 km is likely associated with the Calbuco volcanic plume

May 7, 2015

Weather : some clouds

Time of measurements for lidars (UTC time) :

LIO3S : 13h39 - 15h32 (113 minutes)
LIO3T : 12h46 - 15h34 (168 minutes)
LI1200 : 8h03 - 13h23 (320 minutes) and 13h29 - 15h33 (130 minues)

The li1200 has been launch during the day to observ the plume. Only one channel (355nm low) were connect. During the night, lio3s and li1200 were synchronised.

Information :

at 20h30 (local time), a electrical problem has cut the power of lasers. One of our chiller is down. It wiil be repear Monday.

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

NRT data
li1200: profil of the night
li1200: time serie
li1200: Backscatter ratio

May 11, 2015

Weather : some clouds at the begining of the night, clear sky after, no moon

All sky camera at Maïdo obsevatory
18h20 Begining of the measure
19h00
20h00
21h00
21h30 end of the measure

Time of measurements for lidars (UTC time) :

LIO3S : 18h23 - 21h26 (183 minutes)
LIO3T : 18h43 - 21h28 (165 minutes)
LI1200 : 18h22 - 21h27 (185 minutes)

Informations:

at the begining of the night, we have do some tests to synchronised our lidars : li1200, lio3s and STROZ
the problem of chiller(OPAR system) has been resolved
the li1200 lidar has run with one laser (YAG BAS) (problem with the second laser)

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

NRT data
lio3s: profil of the night
lio3s: backscatter ratio channel 355 low
lio3s: backscatter ratio channel 355 high
li1200: profil of the night
li1200: time serie
li1200: time serie (log)
li1200: backscatter ratio channel 355 low
lio3t: backscatter ratio channel 532 (channel 3)
lio3t: backscatter ratio channel 532 (channel 4)
lio3t: Depolarization

VALIDATED DATA
li1200: temperature profil of the night

May 12, 2015

Weather : clear sky at the begining of the night, some clouds after, no moon

All sky camera at Maïdo obsevatory
18h20 Begining of the measure
19h00
20h00
21h00
21h30 end of the measure

Time of measurements for lidars (UTC time) :

LIO3S : 15h35 - 18h26 (171 minutes)
LIO3T : 15h50 - 18h26 (156 minutes)
LI1200 : 15h31 - 18h26 (175 minutes)

Informations:

the li1200 lidar has run with two lasers

Night pictures at LIDARS rooms

Thumb IMG 8498 1024.jpg Thumb IMG 8493 1024.jpg

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

NRT data
lio3s: profil of the night
li1200: profil of the night
li1200: time serie
li1200: time serie (log)
li1200: backscatter ratio channel 355 low
lio3t: backscatter ratio channel 532 (channel 3)
lio3t: backscatter ratio channel 532 (channel 4)
lio3t: Depolarization

VALIDATED DATA
li1200: temperature profil of the night

May 13, 2015

Weather : clear sky, no moon

All sky camera at Maïdo obsevatory
18h20 Begining of the measure
19h00
20h00
21h00
21h30
21h30
21h30 end of the measure

Time of measurements for lidars (UTC time) :

LIO3S : 15h30 - 20h22 (292 minutes)
LIO3T : 15h46 - 20h22 (276 minutes)
LI1200 : 16h09 - 20h22 (253 minutes)

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

NRT data
lio3s: profil of the night
li1200: profil of the night
li1200: time serie
li1200: time serie (log)
li1200: backscatter ratio channel 355 low
lio3t: backscatter ratio channel 532 (channel 3)
lio3t: backscatter ratio channel 532 (channel 4)
lio3t: Depolarization

VALIDATED DATA
li1200: temperature profil of the night

May 14, 2015

Weather : Heavy rain starting at sunset

Time of measurements for lidars (UTC time) :

LIO3S : No measurement
LIO3T : No measurement
LI1200 : No measurement

All sky camera at Maïdo obsevatory
18h00

May 15, 2015

Time of measurements for lidars (UTC time) :

LIO3S : 19h49 - 22h49 (180 minutes)
LIO3T : 19h00 - 22h49 (229 minutes)
LI1200 : 19h48 - 22h48 (180 minutes)

Raw data
20150515 rawFig lio3t.jpg

lio3t : raw profil of the night
20150515 rawFig lio3s.jpg

lio3s : raw profil of the night
20150515 rawFig li1200.jpg

li1200 : raw profil of the night

May 18, 2015

Time of measurements for lidars (UTC time) :

LIO3S : 15h49 - 20h20 (271 minutes)
LIO3T : 16h00 - 20h20 (260 minutes)
LI1200 : 16h03 - 20h19 (256 minutes)

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

May 19, 2015

Time of measurements for lidars (UTC time) :

LIO3S : 14h52 - 20h08 (316 minutes)
LIO3T : 15h14 - 19h29 (255 minutes)
LI1200 : 14h48 - 20h09 (321 minutes)

Raw data
20150519 rawFig lio3t.jpg

lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

May 20, 2015

Time of measurements for lidars (UTC time) :

LIO3S : 15h29 - 19h39 (250 minutes)
LIO3T : 15h35 - 19h40 (245 minutes)
LI1200 : 15h33 - 19h39 (246 minutes)

Raw data
lio3t : raw profil of the night
lio3s : raw profil of the night
li1200 : raw profil of the night

FLEXPART Lagrangian modeling products

The figures available for download display backward trajectories for the soundings of the MORGANE campaign. There is one tar file per sounding and it contains retroplume summaries for a vertical sounding. For each RS92 radiosonde profile, at 250 m height intervals, 20-day backward trajectories were calculated using the FLEXPART lagrangian model. The meteorological input for FLEXPART was the global operational ECMWF data set. The ECMWF operational analyses are available every 6 hours (00, 06, 12 and 18 UTC) plus hourly forecasts available at intermediate times. The ECMWF data have been retrieved on a regular grid with resolution of 1°x1° at all the 137 vertical model levels. 10000 particles were released at each 250 m altitude from the Maïdo station (the releasing time, latitude, longitude were taken from the RS92 data). The retroplume summary (Stohl et al., Atmos. Environ., 36, 4635-4648, 2002) is a way to display 5-dimensional data. For each release box, every hour, particle positions are assigned to one of 5 groups using a clustering algorithm. The map at the top of the figures corresponds to the positions of the 5 clusters and the retroplume centroid. At the position of every cluster a circle is drawn with the circle's radius scaled with the number of particles the cluster represents (i.e., the fraction of sampled air for which it is representative). The color of the circle indicates the altitude, and the number on top gives the time backward in days. The retroplume's centroid is also displayed by a trajectory (solid black line).

Also shown are time series of the mean altitude of the retroplume (and the five clusters, green circles in the time series, size again indicating the relative fraction of sampled air it represents), the fraction of particles in the boundary layer (ABL), and the fraction of particles in the stratosphere (STR).

For questions regarding the FLEXPART products, please contact Stephanie Evan (stephanie.evan@univ-reunion.fr).

Exemple of retroplume summaries for sounding launched on May 7 at 11:37UTC