Abstract

Abstract. Earth observation (EO) land surface products have been demonstrated to provide a constraint on the terrestrial carbon cycle that is complementary to the record of atmospheric carbon dioxide. We present the Joint Research Centre Two-stream Inversion Package (JRC-TIP) for retrieval of variables characterising the state of the vegetation–soil system. The system provides a set of land surface variables that satisfy all requirements for assimilation into the land component of climate and numerical weather prediction models. Being based on a 1-D representation of the radiative transfer within the canopy–soil system, such as those used in the land surface components of advanced global models, the JRC-TIP products are not only physically consistent internally, but they also achieve a high degree of consistency with these global models. Furthermore, the products are provided with full uncertainty information. We describe how these uncertainties are derived in a fully traceable manner without any hidden assumptions from the input observations, which are typically broadband white sky albedo products. Our discussion of the product uncertainty ranges, including the uncertainty reduction, highlights the central role of the leaf area index, which describes the density of the canopy. We explain the generation of products aggregated to coarser spatial resolution than that of the native albedo input and describe various approaches to the validation of JRC-TIP products, including the comparison against in situ observations. We present a JRC-TIP processing system that satisfies all operational requirements and explain how it delivers stable climate data records. Since many aspects of JRC-TIP are generic, the package can serve as an example of a state-of-the-art system for retrieval of EO products, and this contribution can help the user to understand advantages and limitations of such products.

Highlights

  • This special issue addresses the consistent assimilation of multiple data streams into biogeochemical models

  • Earth observation (EO) land surface products have been demonstrated to provide a constraint on the terrestrial carbon cycle that is complementary to the record of atmospheric carbon dioxide

  • We present the Joint Research Centre Two-stream Inversion Package (JRC-TIP) for retrieval of variables characterising the state of the vegetation–soil system

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Summary

Introduction

This special issue addresses the consistent assimilation of multiple data streams into biogeochemical models. Houweling et al, 2012) provide an indispensable constraint for the (process parameter) calibration of terrestrial biosphere models in carbon cycle data assimilation systems (CCDASs; Rayner et al, 2005). The retrieval of a set of EO products describing the evolution of the canopy–soil system, e.g. leaf area index (LAI) or FAPAR, has to rely on a RT model, in EO terminology called forward model, to simulate the partitioning of the incoming solar radiation into contributions from the individual radiative fluxes, i.e. those absorbed in, transmitted through, and reflected by the canopy. The Joint Research Centre Two-stream Inversion Package (JRC-TIP; Pinty et al, 2007, 2008) is a retrieval package that fulfils the conditions above It is built around a twostream model (Pinty et al, 2006) of the RT in the canopy– soil system

Radiative transfer model
Inverse model
Prior information
Observations
Robustness and efficiency
Understanding uncertainty
Aggregation
Validation
Findings
Conclusions
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