Outputs (26)

Near-infrared digital hemispherical photography enables correction of plant area index for woody material during leaf-on conditions (2023)
Journal Article
Brown, L., Morris, H., Morrone, R., Sinclair, M., Williams, O., Hunt, M., …Dash, J. (2024). Near-infrared digital hemispherical photography enables correction of plant area index for woody material during leaf-on conditions. Ecological Informatics, 79, https://doi.org/10.1016/j.ecoinf.2023.102441

Indirect optical measurement techniques enable efficient and non-destructive estimation of plant area index (PAI). However, because they cannot distinguish between foliage and other canopy elements, corrections are needed to determine leaf area index... Read More about Near-infrared digital hemispherical photography enables correction of plant area index for woody material during leaf-on conditions.

Stage 1 Validation of Plant Area Index from the Global Ecosystem Dynamics Investigation (2023)
Journal Article
Brown, L. A., Morris, H., Meier, C., Knohl, A., Lanconelli, C., Gobron, N., …Danson, F. M. (2023). Stage 1 Validation of Plant Area Index from the Global Ecosystem Dynamics Investigation. IEEE Geoscience and Remote Sensing Letters, 1-1. https://doi.org/10.1109/lgrs.2023.3319528

The Global Ecosystem Dynamics Investigation (GEDI) aims to provide improved characterization of forest structure, and plant area index (PAI) is one of many variables provided in the official GEDI Level 2B (L2B) product suite. However, since release,... Read More about Stage 1 Validation of Plant Area Index from the Global Ecosystem Dynamics Investigation.

HemiPy: A Python module for automated estimation of forest biophysical variables and uncertainties from digital hemispherical photographs (2023)
Journal Article
Brown, L. A., Morris, H., Leblanc, S., Bai, G., Lanconelli, C., Gobron, N., …Dash, J. (in press). HemiPy: A Python module for automated estimation of forest biophysical variables and uncertainties from digital hemispherical photographs. Methods in Ecology and Evolution, https://doi.org/10.1111/2041-210x.14199

Digital hemispherical photography (DHP) is widely used to derive forest biophysical variables including leaf, plant, and green area index (LAI, PAI and GAI), the fraction of intercepted photosynthetically active radiation (FIPAR), and the fraction of... Read More about HemiPy: A Python module for automated estimation of forest biophysical variables and uncertainties from digital hemispherical photographs.

Limited environmental and yield benefits of intercropping practices in smallholder fields: Evidence from multi-source data (2023)
Journal Article
Li, C., Kambombe, O., Gulule Chimimba, E., Fawcett, D., Brown, L., Yu, L., …Dash, J. (2023). Limited environmental and yield benefits of intercropping practices in smallholder fields: Evidence from multi-source data. Field Crops Research, 299, Article 108974. https://doi.org/10.1016/j.fcr.2023.108974

Context To ensure food security in sub-Saharan Africa, it is necessary to improve crop yields while minimizing environmental impacts. Intercropping has been demonstrated to deliver such outcomes, but their performance in smallholder fields has recei... Read More about Limited environmental and yield benefits of intercropping practices in smallholder fields: Evidence from multi-source data.

Assessment of active LiDAR data and passive optical imagery for double-layered mangrove leaf area index estimation: a case study in Mai Po, Hong Kong (2023)
Journal Article
Li, Q., Wong, F. K. K., Kwan, F., Wong, K., Fung, T., Brown, L. A., & Dash, J. (2023). Assessment of active LiDAR data and passive optical imagery for double-layered mangrove leaf area index estimation: a case study in Mai Po, Hong Kong. Remote Sensing, 15(10), 2551. https://doi.org/10.3390/rs15102551

Remote sensing technology is a timely and cost-efficient method for leaf area index (LAI) estimation, especially for less accessible areas such as mangrove forests. Confounded by the poor penetrability of optical images, most previous studies focused... Read More about Assessment of active LiDAR data and passive optical imagery for double-layered mangrove leaf area index estimation: a case study in Mai Po, Hong Kong.

Validation of Simplified Level 2 Prototype Processor Sentinel-2 fraction of canopy cover, fraction of absorbed photosynthetically active radiation and leaf area index products over North American forests (2023)
Journal Article
Fernandes, R., Brown, L., Canisius, F., Dash, J., He, L., Hong, G., …Sun, L. (in press). Validation of Simplified Level 2 Prototype Processor Sentinel-2 fraction of canopy cover, fraction of absorbed photosynthetically active radiation and leaf area index products over North American forests. Remote Sensing of Environment, 293, https://doi.org/10.1016/j.rse.2023.113600

Canopy biophysical variables such as the fraction of canopy cover (fCOVER), fraction of absorbed photosynthetically active radiation (fAPAR), and leaf area index (LAI) are widely used for ecosystem modelling and monitoring. The Sentinel-2 mission was... Read More about Validation of Simplified Level 2 Prototype Processor Sentinel-2 fraction of canopy cover, fraction of absorbed photosynthetically active radiation and leaf area index products over North American forests.

The spatio‐temporal distribution of pollen traits related to dispersal and desiccation tolerance in Canarian laurel forest (2022)
Journal Article
Nogue, S., Nascimento, L. D., Graham, L., Brown, L., Gonzalez, L., Castilla-Beltran, A., …Willis, K. (2022). The spatio‐temporal distribution of pollen traits related to dispersal and desiccation tolerance in Canarian laurel forest. Journal of Vegetation Science, 33(5), https://doi.org/10.1111/jvs.13147

Questions Pollen traits (e.g., size, wall thickness, number of apertures) have been suggested to be relevant in terms of pollination mechanisms and the ability of the male gametophyte to withstand desiccation. We examined the spatiotemporal distribu... Read More about The spatio‐temporal distribution of pollen traits related to dispersal and desiccation tolerance in Canarian laurel forest.

Calibration and characterisation of four chlorophyll meters and transmittance spectroscopy for non-destructive estimation of forest leaf chlorophyll concentration (2022)
Journal Article
Brown, L., Williams, O., & Dash, J. (2022). Calibration and characterisation of four chlorophyll meters and transmittance spectroscopy for non-destructive estimation of forest leaf chlorophyll concentration. Agricultural and forest meteorology, 323, https://doi.org/10.1016/j.agrformet.2022.109059

Chlorophyll meters enable efficient and non-destructive estimation of leaf chlorophyll concentration (LCC), but require calibration against destructively-determined values to provide an absolute quantity that is comparable between different studies a... Read More about Calibration and characterisation of four chlorophyll meters and transmittance spectroscopy for non-destructive estimation of forest leaf chlorophyll concentration.

Maize yield estimation in intercropped smallholder fields using satellite data in southern Malawi (2022)
Journal Article
Li, C., Chimimba, E., Kambombe, O., Brown, L., Chibarabada, T., Lu, Y., …Dash, J. (2022). Maize yield estimation in intercropped smallholder fields using satellite data in southern Malawi. Remote Sensing, 14(10), https://doi.org/10.3390/rs14102458

Satellite data provide high potential for estimating crop yield, which is crucial to understanding determinants of yield gaps and therefore improving food production, particularly in sub-Saharan Africa (SSA) regions. However, accurate assessment of c... Read More about Maize yield estimation in intercropped smallholder fields using satellite data in southern Malawi.

Land surface phenology retrievals for arid and semi-arid ecosystems (2022)
Journal Article
Xie, Q., Cleverly, J., Moore, C., Ding, Y., Hall, C., Ma, X., …Huete, A. (2022). Land surface phenology retrievals for arid and semi-arid ecosystems. ISPRS Journal of Photogrammetry and Remote Sensing, 185, 129-145. https://doi.org/10.1016/j.isprsjprs.2022.01.017

Land surface phenology (LSP) plays a critical role in the regulation of photosynthesis, evapotranspiration, and energy fluxes. Significant progress has been made in extracting LSP information over large areas using satellite data, yet LSP retrievals... Read More about Land surface phenology retrievals for arid and semi-arid ecosystems.

Evaluation of Sentinel-3A and Sentinel-3B ocean land colour instrument green instantaneous fraction of absorbed photosynthetically active radiation (2021)
Journal Article
Gobron, N., Morgan, O., Adams, J., Brown, L., Cappucci, F., Dash, J., …Marioni, M. (2021). Evaluation of Sentinel-3A and Sentinel-3B ocean land colour instrument green instantaneous fraction of absorbed photosynthetically active radiation. Remote Sensing of Environment, 270, https://doi.org/10.1016/j.rse.2021.112850

This article presents the evaluation of the Copernicus Sentinel-3 Ocean Land Colour Instrument (OLCI) operational terrestrial products corresponding to the green instantaneous Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) and its a... Read More about Evaluation of Sentinel-3A and Sentinel-3B ocean land colour instrument green instantaneous fraction of absorbed photosynthetically active radiation.

Fiducial reference measurements for vegetation bio-geophysical variables: an end-to-end uncertainty evaluation framework (2021)
Journal Article
Brown, L., Camacho, F., Garcia-Santos, V., Origo, N., Fuster, B., Morris, H., …Dash, J. (2021). Fiducial reference measurements for vegetation bio-geophysical variables: an end-to-end uncertainty evaluation framework. Remote Sensing, 13(16), https://doi.org/10.3390/rs13163194

With a wide range of satellite-derived vegetation bio-geophysical products now available to users, validation efforts are required to assess their accuracy and fitness for purpose. Substantial progress in the validation of such products has been made... Read More about Fiducial reference measurements for vegetation bio-geophysical variables: an end-to-end uncertainty evaluation framework.

Potential of automated digital hemispherical photography and wireless quantum sensors for routine canopy monitoring and satellite product validation (2021)
Presentation / Conference
Brown, L., Morris, H., Albero, E., Lopez-Baeza, E., Tiedemann, F., Siebecke, L., …Dash, J. (2021, July). Potential of automated digital hemispherical photography and wireless quantum sensors for routine canopy monitoring and satellite product validation. Presented at 2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, Brussels, Belgium

To better characterize the temporal dynamics of vegetation biophysical variables, a variety of automated in situ measurement techniques have been developed in recent years. In this study, we investigated automated digital hemispherical photography (D... Read More about Potential of automated digital hemispherical photography and wireless quantum sensors for routine canopy monitoring and satellite product validation.

Validation of baseline and modified Sentinel-2 level 2 prototype processor leaf area index retrievals over the United States (2021)
Journal Article
Brown, L., Fernandes, R., Djamai, N., Meier, C., Gobron, N., Morris, H., …Dash, J. (2021). Validation of baseline and modified Sentinel-2 level 2 prototype processor leaf area index retrievals over the United States. ISPRS Journal of Photogrammetry and Remote Sensing, 175, 71-87. https://doi.org/10.1016/j.isprsjprs.2021.02.020

The Sentinel-2 Level 2 Prototype Processor (SL2P) is made available to users for the retrieval of vegetation biophysical variables including leaf area index (LAI) from Multispectral Instrument (MSI) data within the Sentinel Application Platform (SNAP... Read More about Validation of baseline and modified Sentinel-2 level 2 prototype processor leaf area index retrievals over the United States.

Deriving leaf area index reference maps using temporally continuous data: a comparison of upscaling approaches (2020)
Journal Article
Brown, L., Ogutu, B., Camacho, F., Fuster, B., & Dash, J. (2020). Deriving leaf area index reference maps using temporally continuous data: a comparison of upscaling approaches. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 14, 624-630. https://doi.org/10.1109/JSTARS.2020.3040080

To further progress the validation of global leaf area index (LAI) products, temporally continuous reference data are a key requirement, as periodic field campaigns fail to adequately characterize temporal dynamics. Progress in cost-effective automat... Read More about Deriving leaf area index reference maps using temporally continuous data: a comparison of upscaling approaches.

Low-cost unmanned aerial vehicle-based digital hemispherical photography for estimating leaf area index: a feasibility assessment (2020)
Journal Article
Brown, L., Sutherland, D., & Dash, J. (2020). Low-cost unmanned aerial vehicle-based digital hemispherical photography for estimating leaf area index: a feasibility assessment. International Journal of Remote Sensing, 41(23), 9064-9074. https://doi.org/10.1080/2150704X.2020.1802527

Unmanned aerial vehicles (UAVs) have the potential to provide highly detailed information on vegetation status useful in precision agriculture. However, challenges are associated with existing techniques for UAV-based retrieval of vegetation biophysi... Read More about Low-cost unmanned aerial vehicle-based digital hemispherical photography for estimating leaf area index: a feasibility assessment.

The Sentinel-3 OLCI Terrestrial Chlorophyll Index (OTCI): algorithm improvements, spatiotemporal consistency and continuity with the MERIS archive (2020)
Journal Article
Pastor-Guzman, J., Brown, L., Morris, H., Bourg, L., Goryl, P., Dransfeld, S., & Dash, J. (2020). The Sentinel-3 OLCI Terrestrial Chlorophyll Index (OTCI): algorithm improvements, spatiotemporal consistency and continuity with the MERIS archive. Remote Sensing, 12(16), https://doi.org/10.3390/rs12162652

The Ocean and Land Colour Instrument (OLCI) on-board Sentinel-3 (2016–present) was designed with similar mechanical and optical characteristics to the Envisat Medium Resolution Imaging Spectrometer (MERIS) (2002–2012) to ensure continuity with a numb... Read More about The Sentinel-3 OLCI Terrestrial Chlorophyll Index (OTCI): algorithm improvements, spatiotemporal consistency and continuity with the MERIS archive.

Evaluation of global leaf area index and fraction of absorbed photosynthetically active radiation products over North America using copernicus ground based observations for validation data (2020)
Journal Article
Brown, L., Meier, C., Morris, H., Pastor-Guzman, J., Bai, G., Lerebourg, C., …Dash, J. (2020). Evaluation of global leaf area index and fraction of absorbed photosynthetically active radiation products over North America using copernicus ground based observations for validation data. Remote Sensing of Environment, 247, https://doi.org/10.1016/j.rse.2020.111935

With a growing number of Earth observation (EO) products available through operational programmes such as the European Union’s Copernicus, there is increasing emphasis on product accuracy and uncertainty, necessitating evaluation against in situ refe... Read More about Evaluation of global leaf area index and fraction of absorbed photosynthetically active radiation products over North America using copernicus ground based observations for validation data.

Tracking forest biophysical properties with automated digital repeat photography: a fisheye perspective using digital hemispherical photography from below the canopy (2020)
Journal Article
Brown, L., Ogutu, B., & Dash, J. (2020). Tracking forest biophysical properties with automated digital repeat photography: a fisheye perspective using digital hemispherical photography from below the canopy. Agricultural and forest meteorology, 287, https://doi.org/10.1016/j.agrformet.2020.107944

In recent years, digital repeat photography has received increasing attention as an inexpensive means by which seasonal changes in vegetation canopies can be monitored. Offering automation and an increased measurement frequency, colour indices derive... Read More about Tracking forest biophysical properties with automated digital repeat photography: a fisheye perspective using digital hemispherical photography from below the canopy.

Estimating peanut leaf chlorophyll content with dorsiventral leaf adjusted indices: minimizing the impact of spectral differences between adaxial and abaxial leaf surfaces (2019)
Journal Article
Xie, M., Wang, Z., Huete, A., Brown, L., Wang, H., Xie, Q., …Ding, Y. (2019). Estimating peanut leaf chlorophyll content with dorsiventral leaf adjusted indices: minimizing the impact of spectral differences between adaxial and abaxial leaf surfaces. Remote Sensing, 11(18), https://doi.org/10.3390/rs11182148

Relatively little research has assessed the impact of spectral differences among dorsiventral leaves caused by leaf structure on leaf chlorophyll content (LCC) retrieval. Based on reflectance measured from peanut adaxial and abaxial leaves and LCC me... Read More about Estimating peanut leaf chlorophyll content with dorsiventral leaf adjusted indices: minimizing the impact of spectral differences between adaxial and abaxial leaf surfaces.

GBOV (Ground-Based Observation for Validation): a copernicus service for validation of vegetation land products (2019)
Presentation / Conference
Bai, G., Dash, J., Brown, L., Meier, C., Lerebourg, C., Ronco, E., …Gobron, N. (2019, July). GBOV (Ground-Based Observation for Validation): a copernicus service for validation of vegetation land products. Presented at 2019 IEEE International Geoscience and Remote Sensing Symposium, Yokohama, Japan

The Copernicus Ground-Based Observations for Validation (GBOV) service aims to develop and distribute robust in-situ datasets from a selection of ground-based monitoring sites for a systematic and quantitative validation of Earth Observation (EO) lan... Read More about GBOV (Ground-Based Observation for Validation): a copernicus service for validation of vegetation land products.

Estimating forest leaf area index and canopy chlorophyll content with Sentinel-2: an evaluation of two hybrid retrieval algorithms (2019)
Journal Article
Brown, L., Ogutu, B., & Dash, J. (2019). Estimating forest leaf area index and canopy chlorophyll content with Sentinel-2: an evaluation of two hybrid retrieval algorithms. Remote Sensing, 11(15), https://doi.org/10.3390/rs11151752

Estimates of biophysical and biochemical variables such as leaf area index (LAI) and canopy chlorophyll content (CCC) are a fundamental requirement for effectively monitoring and managing forest environments. With its red-edge bands and high spatial... Read More about Estimating forest leaf area index and canopy chlorophyll content with Sentinel-2: an evaluation of two hybrid retrieval algorithms.

Retrieval of crop biophysical parameters from Sentinel-2 remote sensing imagery (2019)
Journal Article
Xie, Q., Dash, J., Huete, A., Jiang, A., Yin, G., Ding, Y., …Huang, W. (2019). Retrieval of crop biophysical parameters from Sentinel-2 remote sensing imagery. International Journal of Applied Earth Observation and Geoinformation, 80, 187-195. https://doi.org/10.1016/j.jag.2019.04.019

The red-edge bands place the recently available multispectral Sentinel-2 imagery at an advantage over other multispectral sensors, and hypothetically offer improved crop biophysical variable retrieval accuracy. In this study, Sentinel-2 data was test... Read More about Retrieval of crop biophysical parameters from Sentinel-2 remote sensing imagery.

Synergetic exploitation of the sentinel-2 missions for validating the sentinel-3 ocean and land color instrument terrestrial chlorophyll index over a vineyard dominated Mediterranean environment (2019)
Journal Article
Brown, L., Dash, J., Lidon, A., Lopez-Baeza, E., & Dransfeld, S. (2019). Synergetic exploitation of the sentinel-2 missions for validating the sentinel-3 ocean and land color instrument terrestrial chlorophyll index over a vineyard dominated Mediterranean environment. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 12(7), 2244-2251. https://doi.org/10.1109/jstars.2019.2899998

Continuity to the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) will be provided by the Ocean and Land Color Instrument (OLCI) on-board the Sentinel-3 missions. To ensure its utility in a wide range of scientific... Read More about Synergetic exploitation of the sentinel-2 missions for validating the sentinel-3 ocean and land color instrument terrestrial chlorophyll index over a vineyard dominated Mediterranean environment.

Validation of the Sentinel-3 Ocean and Land Colour Instrument (OLCI) Terrestrial Chlorophyll Index (OTCI): synergetic exploitation of the Sentinel-2 missions (2018)
Presentation / Conference
Brown, L., Dash, J., Lidon, A., Lopez-Baeza, E., & Dransfeld, S. (2018, July). Validation of the Sentinel-3 Ocean and Land Colour Instrument (OLCI) Terrestrial Chlorophyll Index (OTCI): synergetic exploitation of the Sentinel-2 missions. Presented at IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium, Valencia, Spain

Continuity to the Medium Resolution Imaging Spectrometer (MERIS) Terrestrial Chlorophyll Index (MTCI) will be provided by the Sentinel-3 Ocean and Land Colour Instrument (OLCI), and to ensure its utility in a wide range of operational applications, v... Read More about Validation of the Sentinel-3 Ocean and Land Colour Instrument (OLCI) Terrestrial Chlorophyll Index (OTCI): synergetic exploitation of the Sentinel-2 missions.

On the relationship between continuous measures of canopy greenness derived using near-surface remote sensing and satellite-derived vegetation products (2017)
Journal Article
Brown, L., Dash, J., Ogutu, B., & Richardson, A. (2017). On the relationship between continuous measures of canopy greenness derived using near-surface remote sensing and satellite-derived vegetation products. Agricultural and forest meteorology, 247, 280-292. https://doi.org/10.1016/j.agrformet.2017.08.012

Over the last two decades, satellite-derived estimates of biophysical variables have been increasingly used in operational services, requiring quantification of their accuracy and uncertainty. Evaluating satellite-derived vegetation products is chall... Read More about On the relationship between continuous measures of canopy greenness derived using near-surface remote sensing and satellite-derived vegetation products.