1

Pulsed Lidar measurements of XCO2 in the 2017

ASCENDS airborne campaign, & beyond …

James B. Abshire1, Jianping Mao1,2, Haris Riris1,Graham Allan1, Bill Hasselbrack1, Jeff Chen1,

Randy Kawa2, Josh DiGangi2

1- Science and Exploration Directorate, NASA Goddard Space Flight Center

2- AVOCET/DIACOM DLH Team (NASA LaRC)

Support from NASA’s:

ASCENDS Pre-formulation Activity, ABoVE Science Investigation, Airborne Science ProgramIWGGMS-14

Paper 6.12May 10,

2018

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 2

• A very successful airborne campaign - all instruments & aircraft worked well

• Made IPDA lidar measurements in Arctic for the 1st time

• 1st airborne campaigns with long (34–70 deg lat.) north/south flight lines

• 40+ spirals allow comparisons of lidar vs. in-situ XCO2 for a wide variety of

locations & atmospheric conditions

• Will show samples of new results:

• In situ measurements: CO2 was lower & quite variable in Arctic

• Arctic backscatter profile measurements: show considerable variability in

haze, vertical & horizontal cloud structure

• CO2 Sounder lidar worked well – produced a large & rich data set !

• Path to space – made additional & significant progress

Overview & Summary

Overview - 2017 ASCENDS Airborne Campaign

Jul 20- Aug 8, 2017

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 3

Flights & Legend:Dates Name Duration(hrs) #Spirals/Descents

20-Jul Engineering 4.4 3

21-Jul Calibration 5.6 10

27-Jul Northbound science/transit 9.4 4

31-Jul Western NWT 8 6

2-Aug Northern NWT 6.6 4

5-Aug South-Central Alaska 6.2 5

6-Aug Central Alaska 7 7

8-Aug Southbound science/transit 8.1 8

8 Totals: 55.3 47

NASA DC-8 Landing at Fairbanks

Alaska on July 27

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 4

• Direct Detection IPDA lidar - emits 10 kHz train of laser pulses

• Measures column CO2 absorption using 1572.33 nm line.

• Laser pulses - stepped in 30 wavelengths across line.

• Wavelengths are locked relative to CO2 absorption line center

• Time resolved receiver uses HgCdTe APD detector

• Measures backscatter profile, range & samples of CO2 line shape

• XCO2 Retrievals:

• Line shape samples, range to scattering surface

• Atmospheric state (measurements or model)

CO2 Sounder Lidar & other campaign instruments-5

0

5

OD

( 1

0-3

)

Time 23.407 hrs (232425.25) Alt 12257m

rmse from flat = 2.14e-01 (2.21e-01)

rmse from flat = 7.34e-03 (7.74e-03)

1572.2 1572.3 1572.4 1572.5

Wavelength (nm)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

2-w

ay

Op

tic

al

De

pth

LDR Rng = 9759 mGrnd ht = 2581 mTot. Cts. = 374 kOffline SNR = 1645

Meas. Linshp.

Calc. Linshp.

Adj. Linshp

0.99

0.995

1

1.005

1.01

No

rmali

ze

d R

etu

rn

rmse from flat = 2.23e-01 (2.31e-01)

rmse from flat = 7.31e-03 (7.71e-03)

XNR = 9.81

1572.2 1572.3 1572.4 1572.5

Wavelength (nm)

0

0.2

0.4

0.6

0.8

1

Tra

nsm

issio

n

h2o adj. = 0.0% ( 0)

init. conc. = 400.0 ppmv

adj. conc. = 0.2% (401)

range = 400.5-400.7 ppmv

GEOS WV = 0 mm

LDR Rng = 9759 m

Grnd ht = 2581 m

Pul. Int. = 4741 photons

Meas. Linshp.

Calc. Linshp.

Adj. Linshp.

Other science instruments on ASCENDS

2017 campaign

• Picarro (Randy Kawa) – in situ CO2 and WV

• AVOCET (Josh DiGangi/LaRC) – in situ CO2,

CH4, CO

• DLH (Glenn Diskin/LaRC ) – in situ WV

• ACES (Mike Obland/LaRC ) – IPDA lidar to

measure XCO2 using a line near 1571 nm

- Uses modulated CW lasers at 3 wavelengths

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 5

Engineering Flight July 20, 2017

CO2 concentrations at the aircraft:

Color coded Picarro in-situ CO2

measurements made from the DC-8 aircraft

during the flight

Edwards AFB,

CA

Castle

Airport,

Atwood, CA

6

Engineering Flight July 20, 2017Spiral over Edwards CA: CO2 & XCO2 Retrievals

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar

Red dots: XCO2 from CO2 Sounder Lidar

Black dots: CO2 (at altitude) from in situ

All XCO2 Retrievals use 1 second averaging time

Reference atmosphere (LUT)

for XCO2 retrievals based on:

DC-8 T & P

PICARRO H2O

Comparison of XCO2 measurements:

• Red – lidar

• Blue dots - In situ, ave’d to surface

Picarro (in situ) CO2 measurements

at aircraft made during spiral

<- Side view Top view->

Same format used for other sample

results

In situ at Aircraft In situ at Aircraft

Lidar (1 sec)

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 7

ASCENDS 2017 Flight

NWT Canada 1 - Monday July 31, 2017

The route went east from Fairbanks to Inuvik,

then primarily south, east, then back north

along the Mackenzie River, then out of the

Arctic Ocean, over Deadhorse AK, then back

to Fairbanks.

We used 6 spiral-down maneuvers to allow

comparing the lidar measurements of XCO2

against the in-situ measured CO2

In-situ CO2 at the DC-8 (Picarro):

Inuvik

Norman

Wells

Fort

Simpson

Yellowknife

Deadhorse

Flight on Monday July 31, based out of Fairbanks AK.

Takeoff time: 3:45pm local

Flight duration: 8 hours.

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 8

Lidar Measured Backscatter History - NWT Flight 1

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 9

NWT Flight 1 - July 31, 2017

1st Spiral over Inuvik NWT

In situ & XCO2 retrievals show variability with time & altitude

• Red – lidar

• Blue dots - In situ, ave’d to

surface

In situ at Aircraft In situ at Aircraft

Lidar (1 sec)Lidar (1 sec)

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 10

NWT1 Flight – 2nd Spiral: Fort Simpson NWT

Picarro In-situ CO2

Lidar XCO2 & Picarro

8/1 02:30-03:00 UTC

Retrievals Based on REVEAL

& PICARRO data

• Red – lidar

• Blue dots - In situ, ave’d to

surface

In situ at Aircraft In situ at Aircraft

Lidar (1 sec)

Comparison

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 11

Alaska to California Transit Flight - Aug 8, 2017

Takeoff time: 8:15 am local

Duration: 8.1 hours

Flight Events:

• Spiral - Northway Airport AK

• Spiral - Whitehorse Airport YU

• Flew due south over part of

inner passage of British

Columbia

• 2 in-line descent-ascents

over cloud-free areas of ocean

(in inner passage)

• Spiral - Moses Lake, WA

• Spiral - Wildhorse Airport, OR

• Spiral - Winnemucca, NV

• Increased altitude to 38Kft

• Spiral at Edwards AFB, CA

.

In-situ (Picarro) CO2

measurements made from aircraft

Fairbanks

Edwards

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar jba - 12

Aug 8 Flight – 1st Spiral – Northway Junction AK

8/8 17-17:30 UTC

with DC-8 data

In situ at Aircraft In situ at Aircraft

Lidar (1 sec)

Comparison

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar jba - 13

Aug 8 return Flight – 2nd Spiral – Whitehorse YT

Retrievals based on DC-8 data

In situ at Aircraft In situ at Aircraft

Lidar (1 sec)

Comparison

Advances in NASA Goddard’s CO2 Sounder Lidar

Key progress toward

moving the CO2 Sounder Lidar to Space

5-10-18 jba – 14

Launch 2017

ADM- Aeolus telescope

(1.5 m diameter)

3. Measurement model

For space shows < 1 ppm random error

2. Receiver telescope:

80 & 100 cm diameter telescopes:

affordable & flight proven

1. Laser with space needed performance

in testing: TRL-6 by October 2018

4. Detector:

Highly sensitive HgCdTe APD

detector in cryocooler - passed

space radiation & environ. tests

Orbit

average

Advances in NASA Goddard’s CO2 Sounder Lidar

Calipso Mission Image

courtesy of D. Winker/ NASA LaRC

It uniquely provides:

• Measurements at night & high latitudes

• High spatial resolution (small footprint)

• Using consistent vertical path

• Accurate knowledge of path length

- Enables measurements to cloud tops

• Uses 1 line – much simpler spectroscopy

• Multiple wavelengths on gas line shape:

• Allows solving for potential biases

Why a space lidar for XCO2 ?

jba – 155-10-18

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 16

Backup

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 17

Lidar Measured Backscatter History - NWT Flight 1

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 18

Calibration Flight: Central Valley CA, July 21, 2017

CO2 concentrations at the aircraft:

Color coded Picarro in-situ CO2 measurements

made from DC-8 aircraft during the flight

Castle

Airport,

Atwood, CA

Palmdale

5 Spirals up & down (10 total):

3 times over Atwood CA

2 times over Porterville CA

Fairly uniform

CO2 !

Porterville

CA AtwoodPorterville

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 19

Northbound Transit & Science Flight

July 27, 2017 - Palmdale to Fairbanks Alaska

The campaign’s long

south-to-north science

flight occurred on July

27

Takeoff time: 9 am local

Flight duration: 9.4 hrs.

Eastward path to avoid

mountains and clouds

Spiral down maneuvers

at:

• Grand Island, NE

• Minott, ND

• Loon River, Alberta

• Norman Wells, NWT

Norman Wells

NWT

Color coded Picarro in-situ CO2 measurements

made from DC-8 aircraft during the flight

MinottLoon River

NormanWells

Fairbanks Grand Island

NE

Minott

ND

Loon River

Alberta

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 20

ASCENDS Flight - Saturday Aug 5, 2017

1st Alaska Flight - South-Central Alaska

The takeoff time: 9 am local

Flight duration was 6.2 hours.

Spiral-downs at:

Nome, McGrath, Saint Mary’s, Bethel, Fairbanks.

A planned spiral at southernmost point of route

(Platinum) not possible - cloud cover.

22:45:49Fairbanks looking southduring descent

In-situ (Picarro) CO2 measurements made

from aircraft

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 21

ASCENDS Flight - Sunday Aug 6, 2017

2nd Alaska Flight

Spiral-down maneuvers made at:

• Bettles, Kotzebue,

• Unalakleet, Platinum

• McGrath, Fort Yukon

• Fairbanks

Yukon River & Fort Yukon

Photo: Peter Griffith

In-situ (Picarro) CO2 measurements made from

aircraft

• 2nd Alaska science flight was on

Sunday 8/6.

• Takeoff time: 7:45 am local

• Flight duration: 7 hours.

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 22

NWT Flight 2 - August 2, 2017

Takeoff time: 4:46 pm local

Flight duration: 6.6 hours.

Spiral down maneuvers at:

• Inuvik NWT

• Kugluktuk NWT

• Cambridge Bay NU

• Inuvik again

Return west and south Fairbanks.

Fairbanks

Inuvik

Cambridge Bay

In-situ (Picarro) CO2 measurements made from aircraft

Kuglutuk

5-10-18 Advances in NASA Goddard's CO2 Sounder Lidar 23

Initial L2a Retrievals for 1st

Inuvik Spiral on August 3, 2017

Preliminary

Reference atmosphere (LUT) based

on:

Inuvik 0Z radiosonde

CO2 Sounder Lidar: NWT Flight 2 - August 3, 2017

XCO2 Retrievals for 1st Inuvik Spiral

CO2 (ppm) measured at aircraft • Red – lidar

• Blue dots - In situ, ave’d to

surface