Preprints
https://doi.org/10.5194/essd-2024-325
https://doi.org/10.5194/essd-2024-325
14 Aug 2024
 | 14 Aug 2024
Status: this preprint is currently under review for the journal ESSD.

Mapping global leaf inclination angle (LIA) based on field measurement data

Sijia Li and Hongliang Fang

Abstract. Leaf inclination angle (LIA), the angle between leaf surface normal and zenith directions, is a vital parameter in radiative transfer, rainfall interception, evapotranspiration, photosynthesis, and hydrological processes. Due to the difficulty in obtaining large-scale field measurement data, LIA is typically assumed to follow the spherical leaf distribution or simply considered constant for different plant types. However, the appropriateness of these simplifications and the global LIA distribution are still unknown. This study compiled global LIA measurements and generated the first global 500 m mean LIA (MLA) product by gap-filling the LIA measurement data using a random forest regressor. Different generation strategies were employed for noncrops and crops. The MLA product was evaluated by validating the nadir leaf projection function (G(0)) derived from the MLA product with high-resolution reference data. The global MLA is 41.47°±9.55°, and the value increases with latitude. The MLAs for different vegetation types follow the order of cereal crops (54.65°) > broadleaf crops (52.35°) > deciduous needleleaf forest (50.05°) > shrubland (49.23°) > evergreen needleleaf forest (47.13°) ≈ grassland (47.12°) > deciduous broadleaf forest (41.23°) > evergreen broadleaf forest (34.40°). Cross-validation shows that the predicted MLA presents a medium consistency (r = 0.75, RMSE = 7.15°) with the validation samples for noncrops, whereas crops show relatively lower correspondence (r = 0.48 and 0.60 for broadleaf crops and cereal crops) because of limited LIA measurements and strong seasonality. The global G(0) distribution is opposite to that of the MLA and agrees moderately with the reference data (r = 0.62, RMSE = 0.15). This study shows that the common spherical and constant LIA assumptions may underestimate the intercept capability for most vegetation. The MLA and G(0) products derived in this study would enhance our knowledge about global LIA and should greatly facilitate remote sensing retrieval and land surface modeling studies.

The global MLA and G(0) products can be accessed at: Li, S. and Fang, H. 2024, https://doi.org/10.5281/zenodo.10940673.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Sijia Li and Hongliang Fang

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2024-325', Anonymous Referee #1, 22 Sep 2024
    • AC1: 'Reply on RC1', Sijia Li, 09 Oct 2024
  • RC2: 'Comment on essd-2024-325', Anonymous Referee #2, 28 Sep 2024
    • AC2: 'Reply on RC2', Sijia Li, 09 Oct 2024
Sijia Li and Hongliang Fang

Data sets

Global leaf inclination angle (LIA) and nadir leaf projection function (G(0)) products Siia Li and Hongliang Fang https://doi.org/10.5281/zenodo.10940673

Model code and software

The related code for generating global leaf inclination angle Siia Li and Hongliang Fang https://code.earthengine.google.com/?accept_repo=users/SiJia/MTA

Sijia Li and Hongliang Fang

Viewed

Total article views: 512 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
389 92 31 512 41 10 14
  • HTML: 389
  • PDF: 92
  • XML: 31
  • Total: 512
  • Supplement: 41
  • BibTeX: 10
  • EndNote: 14
Views and downloads (calculated since 14 Aug 2024)
Cumulative views and downloads (calculated since 14 Aug 2024)

Viewed (geographical distribution)

Total article views: 464 (including HTML, PDF, and XML) Thereof 464 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 05 Dec 2024
Download
Short summary
Leaf inclination angle (LIA) is a vital parameter in radiative transfer, rainfall interception, evapotranspiration, photosynthesis, and hydrological processes. However, global LIA knowledge is still lacking. This study generated the first global 500 m LIA products by gap-filling LIA measurement data. The global LIA is 41.47°±9.55° and increases with latitude. The LIA products would enhance our understanding of global LIA and assist remote sensing retrieval and land surface modeling studies.
Altmetrics