Aboveground carbon biomass estimate with Physics-informed deep network Juan Nathaniel

2025-04-30 0 0 5.55MB 6 页 10玖币
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Aboveground carbon biomass estimate with
Physics-informed deep network
Juan Nathaniel
Columbia University
NY, USA
Levente J. Klein
IBM Research
Yorktown Heights, NY, USA
Campbell D. Watson
IBM Research
Yorktown Heights, NY, USA
Gabrielle Nyirjesy
Columbia University
NY, USA
Conrad M. Albrecht
German Aerospace Center
Weßling, Germany
Abstract
The global carbon cycle is a key process to understand how our climate is changing.
However, monitoring the dynamics is difficult because a high-resolution robust
measurement of key state parameters including the aboveground carbon biomass
(AGB) is required. Here, we use deep neural network to generate a wall-to-wall map
of AGB within the Continental USA (CONUS) with 30-meter spatial resolution
for the year 2021. We combine radar and optical hyperspectral imagery, with a
physical climate parameter of SIF-based GPP. Validation results show that a masked
variation of UNet has the lowest validation RMSE of 37.93
±
1.36 Mg C/ha, as
compared to 52.30
±
0.03 Mg C/ha for random forest algorithm. Furthermore,
models that learn from SIF-based GPP in addition to radar and optical imagery
reduce validation RMSE by almost
10%
and the standard deviation by
40%
. Finally,
we apply our model to measure losses in AGB from the recent 2021 Caldor wildfire
in California, and validate our analysis with Sentinel-based burn index.
1 Introduction
Aboveground carbon biomass (AGB) is an important component to monitor carbon cycle on the
local [
1
,
2
] and global scale [
3
,
4
]. A recent state-of-the-art light detection and ranging (LiDAR)
mission from NASAs Global Ecosystem Dynamics Investigation (GEDI) generates a global yet
non-continuous sparse measurements of vegetation parameters, including AGB estimates with a
60-meter along-track and 600-meter across-track gaps between footprints [
5
]. Here, we apply a
Physics-informed deep network to generate a 30-meter resolution, wall-to-wall continuous AGB
estimate in CONUS for the summertime (June-August) 2021 period. The model is trained on more
than one million GEDI footprints using a combination of radar and optical imagery [6]. In addition,
we incorporate a measure of photosynthetic intensity as captured by solar-induced fluorescence
(SIF)-based gross primary production (GPP). SIF-based GPP is one of the key physical parameters
regulating AGB [
7
,
8
]. We validate our results using field-based AGB observations and evaluate their
consistency across climate zones. Finally, we use our high resolution AGB map to assess the impact
of wildfire, in terms of how much carbon biomass had been lost to the environment.
Corresponding author (jn2808@columbia.edu)
Tackling Climate Change with Machine Learning: workshop at NeurIPS 2022.
arXiv:2210.13752v1 [cs.LG] 25 Oct 2022
2 Methodology
This section provides a detailed description of the data, models, and evaluation metrics used, and are
summarized in Figure 1.
Sentinel-1 data Bilinear
resampling
Sentinel-2 data Near-cloud-
free filtering
SIF-based GPP
Summertime
averaging
GEDI/Field-
based AGB
Gridcell
matching
Data processing
Training
datacube
Validation
datacube
Datacube
Hyperparameter
optimization
Training
Trained model
Validation
Modeling
Figure 1: Schematic overview that summarizes our data-processing steps at the leftmost panel and
datacube generation during training and validation steps. The modeling process is iterated across
different data setups (SIF/S1/S2, S1/S2, and S2-only) in an ablation study.
2.1 Data Processing
GEDI is one of the current state-of-the-art spaceborne LiDAR missions to capture a detailed measure
of ecosystem structure [
9
]. However, the data generated is spatially sparse. Therefore, we attempt
to produce a dense 30-meter resolution AGB estimate using multiple input features including radar
and optical hyperspectral imagery from Sentinel-1 and Sentinel-2, as well as SIF-based GPP from
the OCO-2 mission [
7
]. We use the vertical co-polarization (VV) and vertical/horizontal cross-
polarization (VH) band of Sentinel-1, and the entire 12 bands of Sentinel-2. Furthermore, we produce
near-cloud-free optical imagery by taking the median value of non-cloudy pixel as defined by the
scene classification layer (SCL) of Sentinel-2. Finally, we perform grid cell geospatial matching to
combine the dataset together. The validation sites are situated in the Northwestern America [
10
] and
New England [11].
2.2 Model and Experimental Setup
We benchmark our deep network model against linear regressor (LR), random forests (RF) [
12
], and
extreme gradient boosting (XGBoost) [
13
] algorithms due to their reported robustness in climate-
related tasks [
14
]. Specifically, we implement a masked variation of UNet [
15
] due to the sparsity
of our target AGB variable [
16
]. The models are optimized using a randomized grid search and a
k-fold cross validation (k=5) approaches. We split the data into a 90-10 training-testing set, where set
here refers to pixels for ML-based models and tiles for deep networks. We use Adam optimizer [
17
]
with a learning rate of 0.01 and root-mean-squared error (RMSE) as our loss function. For the deep
network, we use a size 32 batching and implement a collection of image augmentations including
random horizontal and vertical flipping, as well as cropping to a 512x512 image size. The full deep
network modeling workflow is illustrated in Figure 2.
3 Results and Discussion
This section summarizes and validates our results, showcasing the application of our AGB 30-meter
resolution (Figure 3) to assess how much carbon has been released to the environment from a major
wildfire event.
2
摘要:

AbovegroundcarbonbiomassestimatewithPhysics-informeddeepnetworkJuanNathanielColumbiaUniversityNY,USALeventeJ.KleinIBMResearchYorktownHeights,NY,USACampbellD.WatsonIBMResearchYorktownHeights,NY,USAGabrielleNyirjesyColumbiaUniversityNY,USAConradM.AlbrechtGermanAerospaceCenterWeßling,GermanyAbstractTh...

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