The Eco3D campaign was conducted in the Summer of 2011. As part of the campaign three unique and innovative NASA Goddard Space Flight Center airborne sensors were flown simultaneously: The Digital Beamforming Synthetic Aperture Radar (DBSAR), the Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) and the Cloud Absorption Radiometer (CAR). The campaign covered sites from Quebec to Southern Florida and thereby acquired data over forests ranging from Boreal to tropical wetlands. This paper describes the instruments and sites covered and presents the first images resulting from the campaign

Dabney, Phillip

Fatoyinbo, Temilola

Gatebe, Charles

Harding, David

Ranson, Kenneth Jon

Rincon, Rafael

Roman, Miguel

Sun, Guoqing

NASA Technical Reports Server

THE 2011 ECO3D FLIGHT CAMPAIGN: VEGETATION STRUCTURE AND BIOMASS 
ESTIMATION FROM SIMULTANEOUS SAR, LIDAR AND RADIOMETER MEASUREMENTS 
 
Temilola Fatoyinbo1, Rafael Rincon1, David Harding1, Charles Gatebe1,2, Kenneth Jon Ranson1, 
Guoqing Sun3, Phillip Dabney1, Miguel Roman1, 
 
1 NASA Goddard Space Flight Center, Greenbelt, MD, USA 
2 Universities Space Research Association, Columbia, MD, USA 
3 University of Maryland, College Park, MD, USA 
  
 
ABSTRACT 
	  
The Eco3D campaign was conducted in the 
Summer of 2011. As part of the campaign three 
unique and innovative NASA Goddard Space 
Flight Center airborne sensors were flown 
simultaneously: The Digital Beamforming 
Synthetic Aperture Radar (DBSAR), the Slope 
Imaging Multi-polarization Photon-counting 
Lidar (SIMPL) and the Cloud Absorption 
Radiometer (CAR). The campaign covered sites 
from Quebec to Southern Florida and thereby 
acquired data over forests ranging from Boreal to 
tropical wetlands. This paper describes the 
instruments and sites covered and presents the 
first images resulting from the campaign. 
Index Terms— DBSAR, SIMPLE, CAR, 
Biomass, multisensor  
 
1. INTRODUCTION 
 
Quantifying the carbon cycle is the most 
important element in understanding climate 
change and its consequences, yet is poorly 
understood (Le Toan et al, 2004). Forests store 
85% of terrestrial carbon, yet the amount of 
carbon contained in the earth’s forests is not 
known to even one significant figure, ranging 
from 385 to 650 1015g carbon (Goodale et al. 
2002, Houghton et al. 2009).  
 Recent publications on 3D vegetation 
structure measurements have reiterated the 
urgent need of developing new spaceborne 
sensors capable of three dimensional structure 
measurements to understand changes and trends 
in terrestrial ecosystem function as carbon 
sources and sinks, and to characterize the impact 
of their changes on climate, habitat and 
biodiversity. In particular, the authors concluded 
that lidar profile samplers in combination with L-
band polarimetric SAR data and ecosystem 
modeling can be used to satisfy the vegetation 
3D structure and biomass measurement 
requirements (Hall et al. 2011).  
These measurements of terrestrial 
biomass and ecosystem structure have far 
ranging societal, policy and management 
implications. The anticipated economic and 
societal burden that will result from unmitigated 
rises in CO2 emissions and losses in ecosystem 
services alone are estimated to be in the trillion 
of dollars by mid-century (Stern Report, 2008). 
Ongoing international carbon mitigation 
initiatives, such as the UNFCCC’s Agreement on 
Reduced Emissions from Deforestation and 
Degradation (REDD+) need detailed, precise and 
accurate measurements of carbon storage in 
terrestrial and coastal ecosystems to be 
successful. 
Here were present a recent NASA effort 
towards acquiring these critical measurements 
with three unique and innovative NASA 
Goddard Space Flight Center airborne sensors 
that were flown as part of the Eco3D 
measurement campaign in August-September of 
2011: The L-band Digital Beamforming 
Synthetic Aperture Radar (DBSAR), the Slope 
Imaging Multi-polarization Photon-counting 
https://ntrs.nasa.gov/search.jsp?R=20120014248 2019-08-30T21:59:53+00:00Z
Lidar (SIMPL) and the Cloud Absorption 
Radiometer (CAR), capable of bidirectional 
reflectance (BRDF) measurements.  
 
2. METHODOLOGY 
 
 As a step towards getting multisensor 
fusion forest structure data, the unique and 
innovative DBSAR, SIMPL and CAR sensors 
were flown as part of the Eco3D measurement 
campaign in August and September 2011.  
DBSAR is a digital beamforming L-band 
Synthetic Aperture Radar (SAR) that will 
provide critical information on vegetation 
structure needed to estimate vegetation biomass. 
Digital beamforming permits the implementation 
of non-conventional measurement techniques, 
which can overcome fundamental limitations of 
conventional radar systems (Krieger et al., 2008; 
Yunis et al. 2003) such as increasing the 
measurement swath without reducing the 
received antenna gain, suppressing ambiguities 
or localized interference in the receiver signal 
and synthesizing multiple beams on both sides of 
the aircraft using a single nadir-looking antenna 
(Rincon et al.; 2011A, 2011B, 2010).  
 SIMPL is a multi-beam, micropulse, single 
photon ranging laser altimeter that provides 
measurements of forest canopy structure with 
very high spatial resolution and dual-wavelength 
polarimetry data that can be used to differentiate 
stand types. It incorporates a variety of advanced 
technologies to demonstrate measurement 
approaches of potential benefit for more efficient 
spaceflight laser altimeter missions including 
ICESat-2. It acquires profile data using four 
closely-spaced, nadir-directed laser beams and 
provides a unique combination of capabilities.   
 CAR is an airborne multi-wavelength 
scanning radiometer that can measure spectral 
directional reflectance over uniform forests, 
homogenous clouds, and bright targets. The CAR 
instrument is an airborne multi-wavelength 
scanning radiometer that measures scattered light 
in fourteen spectral bands between 0.34 and 2.30 
µm. The CAR scan mirror rotates 360° in a plane 
perpendicular to the direction of flight and the 
data are collected through a 190° aperture that 
allows observations of the earth-atmosphere 
scene from local zenith to nadir.  
 One of the strength of this instrument is its 
unique ability to measure almost simultaneously, 
both downwelling and upwelling radiance at 14 
narrow spectral bands located in the atmospheric 
window regions of the UV, visible, and near-
infrared. (Gatebe et al., 2003, 2005;2011; 
Lyapustin et al., 2010, Román et al., 2011).  
 The main science objectives of the Eco3D 
flight campaign were:  
i. To acquire coordinated active (lidar and 
radar) and passive (radiometer) data over forest 
ecosystems,  
ii. To evaluate methods for improved 
estimation of forest biophysical properties using 
these complimentary data,  
iii. To measure the 3D structure of temperate 
and subtropical forests, and  
iv. To measure above ground biomass and 
carbon storage in forest ecosystems ranging from 
boreal to subtropical wetlands.    
 The Flights onboard the NASA P3-B 
aircraft were conducted over areas of forests 
from Quebec, Canada to Florida, USA (Table 1). 
The sites were selected to provide a variety land 
cover types with recent ground measurements. 
As a result, the Eco3D measurements represent a 
comprehensive multi-sensor data set over 
diverse, well-characterized forest sites.  
 
 State  Name of Site
 Quebec  • Parc des Laurentides 
 • Foret Montmorency 
 •  Parc de la Jacques-Cartier 
 Maine  • Howland Forest 
New 
 Hampshire
 • Bartlett and Hubbard Brook 
Forests  
 Pennsylvania  • Hickory Run 
Maryland 
 and Virginia
 • Wallops Flight Facility 
 • Smithsonian Ecological Research 
Center 
North 
 Carolina
 • Parker Track 
 Florida •  Everglades National Park
Table	  1	  Field	  Sites	  covered	  by	  Eco3D	  data 
3. RESULTS  
  	   Figure 2 shows the high vertical and spatial 
resolution of canopy structure that is obtained by 
the advanced technology SIMPL instrument. A 
single-photon point at Howland, Maine 
documents structure at tree-crown scales. The 
range histograms that aggregate photons acquired 
over distances of 25 m reveal the canopy layers 
with meter-level vertical resolution. The profile 
location, in yellow is shown on a natural-color, 
nadir video image acquired in-flight.  The low 
noise level is indicated by the count rate below 
the ground.  	  
 
	  
Figure	  1	  SIMPL	  profile	  from	  Howland,	  Maine	  
acquired	  during	  Eco3D	  in	  2011 
 
 The DBSAR measurements provide critical 
information on vegetation structure needed to 
estimate vegetation biomass and structure. 
During the Eco3D campaign, DBSAR acquired 
polarimetric data in repeat-pass and single-pass 
interferometric SAR modes at different heights.  
Figure 2 shows a DBSAR polarimetric RGB 
composite of the Howland, Maine site with the 
associated 1ha field plots.  
 
	  
Figure	   2	   RGB	   composite	   of	   DBSAR	   over	   Howland,	  
Maine.	  HH	   is	  shown	   in	  Red,	  HV	   in	  Green	  and	  VV	   in	  
Blue. 
 Figure 3 shows an example flight path and 
CAR image over Bartlett, New Hampshire. 
Unlike any ground based BRDF measuring 
instrument, which characterizes BRDF over an 
area no larger than tens of meters in diameter, 
CAR can survey the BRDF characteristics of a 
region on the order of kilometers in diameter.  
 A complete circular orbit by the aircraft, 
defined by two solar disks in the image, allows 
the CAR to image the surface and sky in all 
viewing zenith and azimuthal angles, and covers 
an area defined by a diameter of 2–4 km on the 
surface. Note that in the backscattering direction 
(between the solar discs), the surface looks 
brighter than the forward direction (surface 
below the solar disc).  
 
 
 
 
	  	  
Figure	  3	  Quicklook	  CAR	  image	  of	  Bartlett	  Forest	   in	  
all	  zenith	  and	  azimuth	  angles.	  In this RGB quicklook 
image, R=1.036 µm, G=0.870 µm and B=0.472 µm.  
 
4. CONCLUSIONS 
 
The Eco3D SAR, Lidar and Radiometer data 
represents a comprehensive multisensor data set 
over diverse and well-characterized forest sites.  In 
addition to helping to develop new processing 
algorithms and methodologies for radar and lidar 
data, we anticipate that we will gain significant 
knowledge that will aid development and utilization 
of the next generation of sensors that add the 3rd 
dimension to analysis of forest carbon and structure. 
 
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CAR BRDF Measurements: Bartlett Experimental Forest 


The 2011 Eco3D Flight Campaign: Vegetation Structure and Biomass Estimation from Simultaneous SAR, Lidar and Radiometer Measurements

The 2011 Eco3D Flight Campaign: Vegetation Structure and Biomass Estimation from Simultaneous SAR, Lidar and Radiometer Measurements

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