P.R.J. North

• DPhil
• Professor (Full) at Swansea University

The seasonality of sunlight and rainfall regulates net primary production in tropical forests. Previous studies have suggested that light is more limiting than water for tropical forest productivity, consistent with greening of Amazon forests during the dry season in satellite data. We evaluated four potential mechanisms for the seasonal green-up p...

We present a new global dataset of aerosol properties and surface reflectance derived from the AATSR instrument for the period 2003–2009. The algorithm retrieves aerosol optical depth (AOD) and aerosol type over a wide variety of surfaces including ocean, vegetated land and desert. The AATSR dual-view allows retrieval without prior information abou...

We present new coarse resolution (0.5×0.5 degrees) vegetation height and vegetation-cover fraction data sets between 60 degrees S and 60 degrees N for use in climate models and ecological models. The data sets are derived from 2003–2009 measurements collected by the Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud and land Elevation Satel...

The Forest Light (FLIGHT) radiative transfer model was used to examine the uncertainty of vegetation structure measurements from NASA 's planned ICESat-2 photon counting light detection and ranging (LiDAR) instrument across a synthetic Larix forest gradient in the taiga-tundra ecotone. The simulations demonstrate how measurements from the planned s...

Particulate emissions from wildfires impact human health and have a large but uncertain effect on climate. Modelling schemes depend on information about emission factors, emitted particle microphysical and optical properties and ageing effects, while satellite retrieval algorithms make use of characteristic aerosol models to improve retrieval. Grou...

A data record, spanning 24 years, is presented of global atmospheric total aerosol optical depth and also the aerosol optical depth due to fine-mode constituents, typically of anthropogenic origin. Original measurements of reflectance were provided at approximately 1-km resolution by a series of dual-view satellite instruments: the Along-Track Scan...

NASA's (National Aeronautics and Space Administration) ICESat-2 with a Photon Counting LiDAR (Light Detection And Ranging) Sensor was successfully launched in September 2018. The sensor uses an advanced detection system called the Advanced Topographic Laser Altimeter System (ATLAS). The ATLAS sensor detects signal photons at high speed and is highl...

We present the first extended validation of a new SYNERGY global aerosol product (SY_2_AOD), which is based on synergistic use of data from the Ocean and Land Color Instrument (OLCI) and the Sea and Land Surface Temperature Radiometer (SLSTR) sensors aboard the Copernicus Sentinel-3A (S3A) and Sentinel-3B (S3B) satellites. Validation covers period...

The Copernicus program is a European initiative for the implementation of information services dealing with environment and security, mainly based on observation data received from Earth Observation (EO) satellites. In the frame of this program, ESA launched the Copernicus Sentinel-2 and Sentinel-3 optical imaging satellites. These satellites deliv...

We present the first extended validation of a new synergy global aerosol product (SY_2_AOD) which is based on synergistic use of data from the Ocean and Land Color Instrument (OLCI), and the Sea and Land Surface Temperature Radiometer (SLSTR) sensors onboard the Copernicus Sentinel-3A (S3A) and Sentinel-3B (S3B) satellites. Several approaches, incl...

Despite the implication of aerosols for the radiation budget, there are persistent differences in data for the aerosol optical depth (τ) for 1998–2019. This study presents a comprehensive evaluation of the large‐scale spatio‐temporal patterns of mid‐visible τ from modern data sets. In total, we assessed 94 different global data sets from eight sate...

Seasonal maps of dual view retrieved mid-visible AOD and AODf for four selected years (1998, 2008, 2019, 2020) are introduced and assessed in comparisons to MODIS retrievals and general data of an aerosol climatology. Due to different sensor capabilities (ATSR-2, AATSR and SLSTR) there are still unresolved inconsistencies so that decadal regional t...

Holm oak decline is a complex phenomenon mainly influenced by the presence of Phytophthora cinnamomi and water stress. Plant functional traits (PTs) are altered during the decline process — initially affecting the physiological condition of the plants with non-visual symptoms and subsequently the leaf pigment content and canopy structure — being it...

Within the framework of the AeroCom (Aerosol Comparisons between Observations and Models) initiative, the state-of-the-art modelling of aerosol optical properties is assessed from 14 global models participating in the phase III control experiment (AP3). The models are similar to CMIP6/AerChemMIP Earth System Models (ESMs) and provide a robust multi...

An unprecedented spectroscopic data stream will soon become available with forthcoming Earth-observing satellite missions equipped with imaging spectroradiometers. This data stream will open up a vast array of opportunities to quantify a diversity of biochemical and structural vegetation properties. The processing requirements for such large data s...

A major international effort has been made to monitor sun-induced chlorophyll fluorescence (SIF) from space as a proxy for the photosynthetic activity of terrestrial vegetation. However, the effect of spatial heterogeneity on the SIF retrievals from canopy radiance derived from images with medium and low spatial resolution remains uncharacterised....

To better understand and characterize current uncertainties in the important observational constraint of climate models of aerosol optical depth (AOD), we evaluate and intercompare 14 satellite products, representing nine different retrieval algorithm families using observations from five different sensors on six different platforms. The satellite...

Providing accurate information on fire effects is critical to understanding post-fire ecological processes and to design appropriate land management strategies. Multispectral imagery from optical passive sensors is commonly used to estimate fire damage, yet this type of data is only sensitive to the effects in the upper canopy. This paper evaluates...

Abstract. Within the framework of the AeroCom (Aerosol Comparisons between Observations and Models) initiative, the present day modelling of aerosol optical properties has been assessed using simulated data representative for the year 2010, from 14 global aerosol models participating in the Phase III Control experiment. The model versions are close...

Satellite instruments provide a vantage point for studying aerosol loading consistently over different regions of the world. However, the typical lifetime of a single satellite platform is on the order of 5–15 years; thus, for climate studies, the use of multiple satellite sensors should be considered. Discrepancies exist between aerosol optical de...

Abstract. To better understand current uncertainties in the important observational constraint to climate models of AOD (Aerosol Optical Depth), we evaluate and intercompare fourteen satellite products, representing 9 different retrieval algorithm families using observations from 5 different sensors on 6 different platforms. The satellite products,...

ICESat (The Ice, Cloud, and Land Elevation Satellite)-2, as the new generation of NASA (National Aeronautics and Space Administration)’s ICESat mission, had been successfully launched in September 2018. The sensor onboard the satellite is a newly designed photon counting LiDAR (Light Detection And Ranging) system for the first time used in space. F...

Outbreaks of Xylella fastidiosa (Xf) in Europe generate considerable economic and environmental damage, and this plant pest continues to spread. Detecting and monitoring the spatio-temporal dynamics of the disease symptoms caused by Xf at a large scale is key to curtailing its expansion and mitigating its impacts. Here, we combined 3-D radiative tr...

Satellite instruments provide a vantage point to study aerosol loading consistently over different regions of the world. However, the typical lifetime of a single satellite platform is on the order of 5–15 years; thus, for climate studies the usage of multiple satellite sensors should be considered. This paper assesses some options for creating mer...

An unprecedented spectroscopic data stream will soon become available with forthcoming Earth-observing satellite missions equipped with imaging spectroradiometers. This data stream will open up a vast array of opportunities to quantify a diversity of biochemical and structural vegetation properties. The processing requirements for such large data s...

ICESat-2 is the new generation of NASA’s ICESat (Ice, Cloud and land Elevation Satellite) mission launched in September 2018. We investigate the potential of forest parameter estimation using metrics from photon counting LiDAR data, using an integrated dataset including photon counting LiDAR data from SIMPL (the Slope Imaging Multi-polarization Pho...

The Ice, Cloud, and land Elevation Satellite (ICESat)-2 is the next generation of National Aeronautics and Space Administration (NASA)'s ICESat mission launched in September 2018. The new photon-counting LiDAR onboard ICESat-2 introduces new challenges to the estimation of forest parameters and their dynamics, the greatest being the abundant photon...

The authors wish to make the following corrections to this paper [...]

The 3-D Radiative Transfer Model (RTM) FLIGHT can represent scattering in open forest or savannas featuring underlying bare soils. However, FLIGHT might not be suitable for multilayered tree-grass ecosystems (TGE), where a grass understory can dominate the reflectance factor (RF) dynamics due to strong seasonal variability and low tree fractional c...

This paper presents decadal simulations of stratospheric and tropospheric aerosol and its radiative effects by the chemistry general circulation model EMAC constrained with satellite observations in the framework of the ESA Aerosol CCI project such as GOMOS (Global Ozone Monitoring by Occultation of Stars) and (A)ATSR ((Advanced) Along Track Scanni...

The European Space Agency’s (ESA’s) Aerosol Climate Change Initiative (CCI) project intends to exploit the robust, long-term, global aerosol optical thickness (AOT) dataset from Europe’s satellite observations. Newly released Swansea University (SU) aerosol products include AATSR retrieval and synergy between AATSR and MERIS with a spatial resoluti...

Europe’s major X. fastidiosa outbreaks have progressed steadily in the past years as data on the bacterial strains causing them, and on the host range and vectors of the pathogen in various regions, became available. The initial uncertainty around these critical epidemiological aspects of the X. fastidiosa invasions hampered estimates of their rate...

Plant pathogens cause significant losses to agricultural yields and increasingly threaten food security 1 , ecosystem integrity and societies in general2-5. Xylella fastidiosa is one of the most dangerous plant bacteria worldwide, causing several diseases with profound impacts on agriculture and the environment 6 . Primarily occurring in the Americ...

This paper presents decadal simulations of stratospheric and tropospheric aerosol by the chemistry general circulation model EMAC constrained with satellite observations in the framework of the ESA-Aerosol-CCI project like GOMOS (Global Ozone Monitoring by Occultation of Stars) and (A)ATSR ((Advanced) Along Track Scanning Radiometer) on ENVISAT (Eu...

Although traditional remote sensing systems based on spectral reflectance can already provide estimates of the “potential” photosynthetic activity of terrestrial vegetation through the quantification of total canopy chlorophyll content or absorbed photosynthetic radiation, the determination of the “actual” photosynthetic activity of terrestrial veg...

Particulate matter emissions from wildfires affect climate, weather and air quality. However, existing global and regional aerosol emission estimates differ by a factor of up to 4 between different methods. Using a novel approach, we estimate daily total particulate matter (TPM) emissions from large wildfires in North American boreal and temperate...

Sun-induced fluorescence (SIF) has been proven to serve as a proxy of photosynthesis activity and therefore, as an early indicator of physiological alterations for global monitoring of vegetation. However, the interpretation of SIF over different spatial resolutions is critical to bridge the existing gap between local and global scales. This study...

The Geoscience Laser Altimeter System (GLAS) has the potential to accurately map global vegetation heights and fractional cover metrics using active laser pulse emission/reception. However, large uncertainties in the derivation of data products exist, since multiple physically plausible interpretations of the data are possible. In this study a meth...

Particulate matter emissions from wildfires affect climate, weather and air quality. However, existing global and regional aerosol emission estimates differ by a factor of up to 4 between different methods. Using a novel approach, we estimate daily total particular matter (TPM) emissions from large wildfires in North American boreal and temper ate...

Land Surface Temperature (LST) is one of the key parameters in the physics of land-surface processes on regional and global scales, combining the results of all surface-atmosphere interactions and energy fluxes between the surface and the atmosphere. With the advent of the ESA's Sentinel 3 (S3) satellite, accurate LST retrieval methodologies exploi...

Producing a global and comprehensive description of atmospheric aerosols requires integration of ground-based, airborne, satellite and model datasets. Due to its complexity, aerosol monitoring requires the use of several data records with complementary information content. This paper describes the lessons learned while developing and qualifying alg...

Particulate emissions from wildfires impact human health and have a large but uncertain effect on climate. Modelling schemes depend on information about emission factors, emitted particle microphysical and optical properties and ageing effects, while satellite retrieval algorithms make use of characteristic aerosol models to improve retrieval. Grou...

We develop a method to derive aerosol properties over land surfaces using combined spectral and angular information, such as available from ESA Sentinel-3 mission, to be launched in 2015. A method of estimating aerosol optical depth (AOD) using only angular retrieval has previously been demonstrated on data from the ENVISAT and PROBA-1 satellite in...

Satellite data are increasingly used to provide observation-based estimates of the effects of aerosols on climate. The Aerosol-cci project, part of the European Space Agency‟s Climate Change Initiative (CCI), was designed to provide essential climate variables for aerosols from satellite data. Eight algorithms, developed for the retrieval of aeroso...

We present a novel technique to infer ground slope angle from waveform LiDAR, known as the independent slope method (ISM). The technique is applied to large footprint waveforms (∼60 m mean diameter) from the Ice, Cloud and Land Elevation Satellite (ICESat) Geoscience Laser Altimeter System (GLAS) to produce a slope dataset of near-global coverage a...

zip file contains documentation and a file in netcdf format with vegetation height distributions between 0 and 70 m at 0.5 m intervals and at 0.5 by 0.5 degrees resolution. analysis is extended to 80 degrees N (previously to 60 degrees N).

We develop a method to derive aerosol properties over land surfaces using combined spectral and angular information, such as available from ESA Sentinel-3 mission, to be launched in 2015. A method of estimating AOD using only angular retrieval has previously been demonstrated on data from the ENVISAT and PROBA-1 satellite instruments, and is extend...

The effects on climate of land-cover change, predominantly from the conversion of forests to crops or grassland, are reasonably well understood for low and high latitudes but are largely unknown for temperate latitudes. The main reason for this gap in our knowledge is that there are compensating effects on the energy and water balance that are rela...

Leaf area index (LAI) is one of the key parameters for the calculation of the energy budget, photosynthesis, and the interception of precipitation in land-surface models at local to global scales. Estimation of LAI from satellite data is a challenging and difficult problem. Studies over the past decades have focused predominantly on the improvement...

The effects on climate of land-cover change, predominantly from the conversion of forests to crops or grassland, are reasonably well understood for low and high latitudes but are largely unknown for temperate latitudes. The main reason for this gap in our knowledge is that there are compensating effects on the energy and water balance that are rela...

Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (2010–2013), algorithms for the production of long-term total column aerosol optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithm...

The European drought and heat wave of 2003 is commonly used as an example of extreme summer climate conditions that are likely to become more common towards the end of the 21st century, under predicted climate change scenarios. The extreme conditions are known to have had an impact on biomass primary productivity as reflected in remotely sensed veg...

A method has been developed to estimate Aerosol Optical Depth (AOD) and Single Scattering Albedo (SSA) over land surfaces using high spatial resolution, hyperspectral, multi-angle CHRIS/PROBA images. The Compact High Resolution Imaging Spectrometer (CHRIS) instrument is mounted aboard the Project for On Board Autonomy 1 (PROBA-1) satellite, and pro...

Predicting Slope from Full Waveform LiDAR

Radiative transfer models predicting the bidirectional reflectance factor (BRF) of leaf canopies are powerful tools that relate biophysical parameters such as leaf area index (LAI), fractional vegetation cover f(V) and the fraction of photosynthetically active radiation absorbed by the green parts of the vegetation canopy (f(APAR)) to remotely sens...

Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (2010-2013) algorithms for the production of long-term total column aerosol optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms...

A space-based full-waveform LiDAR system, optimised for vegetation analysis, offers the opportunity for global biophysical parameter retrieval of the world's forests. However the conditions under which signals from the ground and vegetation can be detected will vary as a result of sensor specifications, vegetation characteristics and underlying sur...

This document is the final report of the SEN4LST project. It includes a review of land surface temperature retrieval algorithms as well as methodologies for atmospheric correction and cloud screening. Candidate algorithms to be applied to Sentinel-3 OLCI & SLSTR data were selected and validated from simulated S3 data and also using MERIS/AATSR pair...

This document provides a review of candidate atmospheric correction methodologies and land surface emissivity/temperature correction algorithms to be applied to Sentinels 2 and 3 data. The document also explores the adaptation of these algorithms to Sentinels characteristics, as well as a sensitivity analysis of the different algorithms.

The Synergy processing of Sentinel-3 aims at making use of the combined information from the OLCI and SLSTR instruments to provide improved data for land surface vegetation analysis. The L2 processing makes use of the enhanced spectral and angular capabilities of a combined instrument (the SYN instrument) to produce a product with atmosphere-correc...

In this work we explore the synergistic use of future MSI instrument on board Sentinel-2 platform and OLCI/SLSTR instruments on board Sentinel-3 platform in order to improve LST products currently derived from the single AATSR instrument on board the ENVI-SAT satellite. For this purpose, the high spatial resolution data from Setinel2/MSI will be us...

This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD) during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify the differences between current datasets. The satellite instruments considered...

Export Date: 26 October 2012, Source: Scopus, CODEN: PREAF, doi: 10.1007/s11119-012-9263-8, Language of Original Document: English, Correspondence Address: Zarco-Tejada, P. J.; Instituto de Agricultura Sostenible (IAS), Consejo Superior de Investigaciones Científicas (CSIC), Alameda del Obispo, s/n, 14004 Córdoba, Spain; email: pzarco@ias.csic.es,...

This paper describes the algorithm underlying the ESA DUE globAlbedo product. The purpose of the project is to produce a global 8-day land surface albedo product with associated uncertainty on a 1 km grid with continuous spatial coverage using data from European sensors. The product covers the period 1999-2011.

The MERIS and AATSR instruments onboard ENVISAT provide similar resolution and swath but complementary information, encompassing different spectral domains and viewing geometries. We present research on synergistic use of MERIS and AATSR imagery, with objectives (i) to define and evaluate algorithms for improved cloud screening, global aerosol retr...

Methods of estimating stemwood volume from ICESat/ GLAS lidar waveforms are explored for a mixed temperate forest, the Forest of Dean, Gloucestershire, UK. Previous methods have used maximum canopy height estimations incorporating a digital terrain model (DTM) and requiring calibration using a sample of within-footprint tree heights. This study foc...

Land Surface Temperature (LST) is one of the key parameters in the physics of land-surface processes on regional and global scales, combining the results of all the surface-atmosphere interactions and energy fluxes between the surface and the atmosphere. Because of the strong heterogeneity in land surface characteristics such as vegetation, topogra...

Terrestrial plant productivity tends to increase under increasing but non-saturating photosynthetically active solar radiation when water, temperature and nutrients are not limiting. However, studies have shown that photosynthesis can also be higher under enhanced diffuse light despite a decrease in total irradiance. Clouds and atmospheric aerosols...

We present new coarse resolution (0:5� �0:5�) vegetation height and vegetation-cover fraction data sets between 60� S and 60� N for use in climate models and ecological models. The data sets are derived from 2003–2009 measurements collected by the Geoscience Laser Altimeter System (GLAS) on the Ice, Cloud and land Elevation Satellite (ICESat), the...

This work provides a comparison of satellite retrievals of Saharan desert dust aerosol optical depth (AOD) during a strong dust event through March 2006. In this event, a large dust plume was transported over desert, vegetated, and ocean surfaces. The aim is to identify and understand the differences between current algorithms, and hence improve fu...

We present results of global aerosol retrieval from the ESA ATSR instrument series on ERS-2 and ENVISAT (1995-2010), and initial testing of a new algorithm developed for Sentinel-3, with planned operation 2013-2030. The ATSR instruments on ERS-2 and ENVISAT together provide one of the longest available, well-calibrated datasets of satellite radianc...

The seasonality of light and moisture availability governs net ecosystem production in tropical forests. Whether tropical forest productivity is more limited by light or moisture remains an area of active debate. Recent satellite-based studies support the light limitation hypothesis, as Amazon forests respond with higher productivity through leaf t...

This document provides a summary of the campaign datasets analysed and the data selected for the creation of the SEN4LST dataset. The document is structured in five sections besides this introduction: the second section details the origin of the campaign data; the third is dedicated to the organisation of the new SEN4LST dataset; the fourth specifi...

This paper presents a method to estimate forest parameters and surface topography from NASA’s Geosciences Laser Altimeter System (GLAS). Their potential use as observational inputs to models is demonstrated using a wind-risk model for the UK, ForestGALES. Relative heights above ground were used as biophysical parameter estimators. Top Height was es...

We present results of global aerosol retrieval from the ESA ATSR instrument series on ERS-2 and ENVISAT (1995-2010), and initial testing of a new algorithm developed for Sentinel-3, with planned operation 2014-2030. The ATSR instruments on ERS-2 and ENVISAT together provide one of the longest available, well-calibrated datasets of satellite radianc...

Forest attributes such as aboveground woody biomass are commonly derived from LiDAR waveforms using empirical relationships with relative height metrics, i.e., percentiles of returned energy relative to the ground elevation. However, LiDAR waveforms and height metrics are strongly influenced by the reflectance properties of vegetation, soils, and l...