Retrieval of solar-induced chlorophyll fluorescence (SIF) from satellite measurements: comparison of SIF between TanSat and OCO-2
<p>Solar-induced chlorophyll fluorescence (SIF) is emitted during photosynthesis in plant leaves. It constitutes a small additional offset to reflected radiance and can be observed by sensitive instruments with high signal-to-noise ratio and spectral resolution. The Chinese global carbon dioxi...
| Main Authors: | , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-04-01
|
| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/15/2125/2022/amt-15-2125-2022.pdf |
| Summary: | <p>Solar-induced chlorophyll fluorescence (SIF) is emitted
during photosynthesis in plant leaves. It constitutes a small additional
offset to reflected radiance and can be observed by sensitive instruments
with high signal-to-noise ratio and spectral resolution. The Chinese global
carbon dioxide monitoring satellite (TanSat) acquires measurements of
greenhouse gas column densities. The advanced technical characteristics of
the Atmospheric
Carbon-dioxide Grating Spectrometer (ACGS) onboard TanSat enable SIF retrievals from
observations in the O<span class="inline-formula"><sub>2</sub></span>-A band. In this study, 1-year of SIF data was
retrieved from Orbiting Carbon Observatory-2 (OCO-2) and TanSat measurements using the Institute of Atmospheric
Physics Carbon Dioxide Retrieval Algorithm for Satellite Remote Sensing
(IAPCAS)/SIF algorithm. A comparison between the IAPCAS/SIF results retrieved from OCO-2 spectra and the official OCO-2 SIF product (OCO2_Level 2_Lite_SIF.8r)
shows a strong linear relationship (<span class="inline-formula"><i>R</i><sup>2</sup></span> <span class="inline-formula">></span> 0.85) and suggests
good reliability of the IAPCAS/SIF retrieval algorithm. Comparing global
distributions of SIF retrieved by the IAPCAS/SIF from TanSat and OCO-2 shows the same spatial pattern for all seasons with a gridded SIF difference of less than 0.3 W m<span class="inline-formula"><sup>−2</sup></span> <span class="inline-formula">µ</span>m<span class="inline-formula"><sup>−1</sup></span> sr<span class="inline-formula"><sup>−1</sup></span>. The global distributions also agree well with the official OCO-2 SIF product with a difference of less than 0.2 W m<span class="inline-formula"><sup>−2</sup></span> <span class="inline-formula">µ</span>m<span class="inline-formula"><sup>−1</sup></span> sr<span class="inline-formula"><sup>−1</sup></span>. The retrieval uncertainty of seasonally gridded TanSat IAPCAS/SIF is less than 0.03 W m<span class="inline-formula"><sup>−2</sup></span> <span class="inline-formula">µ</span>m<span class="inline-formula"><sup>−1</sup></span> sr<span class="inline-formula"><sup>−1</sup></span>, whereas the uncertainty of each sounding ranges from 0.1 to 0.6 W m<span class="inline-formula"><sup>−2</sup></span> <span class="inline-formula">µ</span>m<span class="inline-formula"><sup>−1</sup></span> sr<span class="inline-formula"><sup>−1</sup></span>. The relationship between
annually averaged SIF products and FLUXCOM gross primary productivity (GPP)
was also estimated for six vegetation types in a 1<span class="inline-formula"><sup>∘</sup></span> <span class="inline-formula">×</span> 1<span class="inline-formula"><sup>∘</sup></span> grid over the globe, indicating that the SIF data from the two
satellites have the same potential in quantitatively characterizing
ecosystem productivity. The spatiotemporal consistency between TanSat and
OCO-2 and their comparable data quality enable joint usage of the two
mission products. Data supplemented by TanSat observations are expected to
contribute to the development of global SIF maps with more spatiotemporal
detail, which will advance global research on vegetation photosynthesis.</p> |
|---|---|
| ISSN: | 1867-1381 1867-8548 |