chore: sync ORCID publications

Author: github-actions[bot]

publications/anema2024monitoring.qmd

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+---
+title: 'Improving Estimates of Gross Primary Productivity by Assimilating Solar‐Induced Fluorescence Satellite Retrievals in a Terrestrial Biosphere Model Using a Process‐Based SIF Model'
+author: 'Bacour, C. and Maignan, F. and MacBean, N. and Porcar‐Castell, A. and Flexas, J. and Frankenberg, C. and Peylin, P. and Chevallier, F. and Vuichard, N. and Bastrikov, V.'
+type: 'journal-article'
+year: 2019
+publication: 'Journal of Geophysical Research: Biogeosciences'
+doi: '10.1029/2019jg005040'
+materials: ''
+supplement: ''
+orcid_type: 'journal-article'
+toc: false
+---
+
+## Abstract
+
+AbstractOver the last few years, solar‐induced chlorophyll fluorescence (SIF) observations from space have emerged as a promising resource for evaluating the spatio‐temporal distribution of gross primary productivity (GPP) simulated by global terrestrial biosphere models. SIF can be used to improve GPP simulations by optimizing critical model parameters through statistical Bayesian data assimilation techniques. A prerequisite is the availability of a functional link between GPP and SIF in terrestrial biosphere models. Here we present the development of a mechanistic SIF observation operator in the ORCHIDEE (Organizing Carbon and Hydrology In Dynamic Ecosystems) terrestrial biosphere model. It simulates the regulation of photosystem II fluorescence quantum yield at the leaf level thanks to a novel parameterization of non‐photochemical quenching as a function of temperature, photosynthetically active radiation, and normalized quantum yield of photochemistry. It emulates the radiative transfer of chlorophyll fluorescence to the top of the canopy using a parametric simplification of the SCOPE (Soil Canopy Observation Photosynthesis Energy) model. We assimilate two years of monthly OCO‐2 (Orbiting Carbon Observatory‐2) SIF product at 0.5° (2015–2016) to optimize ORCHIDEE photosynthesis and phenological parameters over an ensemble of grid points for all plant functional types. The impact on the simulated GPP is considerable with a large decrease of the global scale budget by 28 GtC/year over the period 1990–2009. The optimized GPP budget (134/136 GtC/year over 1990–2009/2001–2009) remarkably agrees with independent GPP estimates, FLUXSAT (137 GtC/year over 2001–2009) in particular and FLUXCOM (121 GtC/year over 1990–2009). Our results also suggest a biome dependency of the SIF‐GPP relationship that needs to be improved for some plant functional types.

publications/bacour2019improving.qmd

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+---
+title: 'The Importance of Hyperspectral Soil Albedo Information for Improving Earth System Model Projections'
+author: 'Braghiere, R. K. and Wang, Y. and Gagné‐Landmann, A. and Brodrick, P. G. and Bloom, A. A. and Norton, A. J. and Ma, S. and Levine, P. and Longo, M. and Deck, K. and Gentine, P. and Worden, J. R. and Frankenberg, C. and Schneider, T.'
+type: 'journal-article'
+year: 2023
+publication: 'AGU Advances'
+doi: '10.1029/2023av000910'
+materials: ''
+supplement: ''
+orcid_type: 'journal-article'
+toc: false
+---
+
+## Abstract
+
+AbstractEarth system models (ESMs) typically simplify the representation of land surface spectral albedo to two values, which correspond to the photosynthetically active radiation (PAR, 400–700 nm) and the near infrared (NIR, 700–2,500 nm) spectral bands. However, the availability of hyperspectral observations now allows for a more direct retrieval of ecological parameters and reduction of uncertainty in surface reflectance. To investigate sensitivity and quantify biases of incorporating hyperspectral albedo information into ESMs, we examine how shortwave soil albedo affects surface radiative forcing and simulations of the carbon and water cycles. Results reveal that the use of two broadband values to represent soil albedo can introduce systematic radiative‐forcing differences compared to a hyperspectral representation. Specifically, we estimate soil albedo biases of ±0.2 over desert areas, which can result in spectrally integrated radiative forcing divergences of up to 30 W m−2, primarily due to discrepancies in the blue (404–504 nm) and far‐red (702–747 nm) regions. Furthermore, coupled land‐atmosphere simulations indicate a significant difference in net solar flux at the top of the atmosphere (>3.3 W m−2), which can impact global energy fluxes, rainfall, temperature, and photosynthesis. Finally, simulations show that considering the hyperspectrally resolved soil reflectance leads to increased maximum daily temperatures under current and future CO<sub>2</sub> concentrations.

publications/braghiere2023the.qmd

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+---
+title: 'Satellite-derived methane hotspot emission estimates using a fast data-driven method'
+author: 'Buchwitz, Michael and Schneising, Oliver and Reuter, Maximilian and Heymann, Jens and Krautwurst, Sven and Bovensmann, Heinrich and Burrows, John P. and Boesch, Hartmut and Parker, Robert J. and Somkuti, Peter and Detmers, Rob G. and Hasekamp, Otto P. and Aben, Ilse and Butz, André and Frankenberg, Christian and Turner, Alexander J.'
+type: 'journal-article'
+year: 2017
+publication: 'Atmospheric Chemistry and Physics'
+doi: '10.5194/acp-17-5751-2017'
+materials: ''
+supplement: ''
+orcid_type: 'journal-article'
+toc: false
+---
+
+## Abstract
+
+Abstract. Methane is an important atmospheric greenhouse gas and an adequate understanding of its emission sources is needed for climate change assessments, predictions, and the development and verification of emission mitigation strategies. Satellite retrievals of near-surface-sensitive column-averaged dry-air mole fractions of atmospheric methane, i.e. XCH<sub>4</sub>, can be used to quantify methane emissions. Maps of time-averaged satellite-derived XCH<sub>4</sub> show regionally elevated methane over several methane source regions. In order to obtain methane emissions of these source regions we use a simple and fast data-driven method to estimate annual methane emissions and corresponding 1σ uncertainties directly from maps of annually averaged satellite XCH<sub>4</sub>. From theoretical considerations we expect that our method tends to underestimate emissions. When applying our method to high-resolution atmospheric methane simulations, we typically find agreement within the uncertainty range of our method (often 100 %) but also find that our method tends to underestimate emissions by typically about 40 %. To what extent these findings are model dependent needs to be assessed. We apply our method to an ensemble of satellite XCH<sub>4</sub> data products consisting of two products from SCIAMACHY/ENVISAT and two products from TANSO-FTS/GOSAT covering the time period 2003–2014. We obtain annual emissions of four source areas: Four Corners in the south-western USA, the southern part of Central Valley, California, Azerbaijan, and Turkmenistan. We find that our estimated emissions are in good agreement with independently derived estimates for Four Corners and Azerbaijan. For the Central Valley and Turkmenistan our estimated annual emissions are higher compared to the EDGAR v4.2 anthropogenic emission inventory. For Turkmenistan we find on average about 50 % higher emissions with our annual emission uncertainty estimates overlapping with the EDGAR emissions. For the region around Bakersfield in the Central Valley we find a factor of 5–8 higher emissions compared to EDGAR, albeit with large uncertainty. Major methane emission sources in this region are oil/gas and livestock. Our findings corroborate recently published studies based on aircraft and satellite measurements and new bottom-up estimates reporting significantly underestimated methane emissions of oil/gas and/or livestock in this area in EDGAR.

publications/braghiere2023tipping.qmd

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+---
+title: 'Potential of next-generation imaging spectrometers to detect and quantify methane point sources from space'
+author: 'Cusworth, Daniel H. and Jacob, Daniel J. and Varon, Daniel J. and Chan Miller, Christopher and Liu, Xiong and Chance, Kelly and Thorpe, Andrew K. and Duren, Riley M. and Miller, Charles E. and Thompson, David R. and Frankenberg, Christian and Guanter, Luis and Randles, Cynthia A.'
+type: 'journal-article'
+year: 2019
+publication: 'Atmospheric Measurement Techniques'
+doi: '10.5194/amt-12-5655-2019'
+materials: ''
+supplement: ''
+orcid_type: 'journal-article'
+toc: false
+---
+
+## Abstract
+
+Abstract. We examine the potential for global detection of methane plumes from
+individual point sources with the new generation of spaceborne imaging
+spectrometers (EnMAP, PRISMA, EMIT, SBG, CHIME) scheduled for launch in
+2019–2025. These instruments are designed to map the Earth's surface at high
+spatial resolution (30 m×30 m) and have a spectral resolution
+of 7–10 nm in the 2200–2400 nm band that should also allow useful detection
+of atmospheric methane. We simulate scenes viewed by EnMAP (10 nm spectral
+resolution, 180 signal-to-noise ratio) using the EnMAP end-to-end simulation tool with superimposed methane plumes generated by large-eddy simulations.
+We retrieve atmospheric methane and surface reflectivity for these scenes
+using the IMAP-DOAS optimal estimation algorithm. We find an EnMAP precision
+of 3 %–7 % for atmospheric methane depending on surface type. This allows
+effective single-pass detection of methane point sources as small as 100 kg h−1 depending on surface brightness, surface homogeneity, and wind speed. Successful retrievals over very heterogeneous surfaces such as an
+urban mosaic require finer spectral resolution. We tested the EnMAP
+capability with actual plume observations over oil/gas fields in California
+from the Airborne Visible/Infrared Imaging Spectrometer – Next Generation (AVIRIS-NG) sensor (3 m×3 m pixel resolution,
+5 nm spectral resolution, SNR 200–400), by spectrally and spatially
+downsampling the AVIRIS-NG data to match EnMAP instrument specifications.
+Results confirm that EnMAP can successfully detect point sources of
+∼100 kg h−1 over bright surfaces. Source rates inferred
+with a generic integrated mass enhancement (IME) algorithm were lower for
+EnMAP than for AVIRIS-NG. Better agreement may be achieved with a more
+customized IME algorithm. Our results suggest that imaging spectrometers in
+space could play an important role in the future for quantifying methane
+emissions from point sources worldwide.