A carbon sink-driven approach to estimate gross primary production from microwave satellite observations

REMOTE SENSING OF ENVIRONMENT

卷:229

Article

Teubner, Irene E.¹  Forkel, Matthias¹  Camps-Valls, Gustau²  Jung, Martin³  Miralles, Diego G.⁴  Tramontana, Gianluca⁵  van der Schalie, Robin⁶  Vreugdenhil, Mariette¹  Moesinger, Leander¹  Dorigo, Wouter A.¹ 

[1] TU Wien, Dept Geodesy & Geoinformat, Gusshausstr 27-29, A-1040 Vienna, Austria

[2] Univ Valencia, Image & Signal Proc Grp ISP, Calle Catedrat Jose Beltran 2, Valencia 46980, Spain

[3] Max Planck Inst Biogeochem, Dept Biogeochem Integrat, POB 10 01 64, D-07701 Jena, Germany

[4] Univ Ghent, Lab Hydrol & Water Management, Campus Coupure,Coupure Links 653, B-9000 Ghent, Belgium

[5] Tuscia Univ, Dept Innovat Biol Agrofood & Forest Syst DIBAF, Via San Camillo de Lellis Snc, I-01100 Viterbo, Italy

[6] VanderSat BV, Wilhelminastr 43a, NL-2011 VK Haarlem, Netherlands

关键词: Microwave remote sensing;    Vegetation optical depth;    Ecosystem productivity;    ASCAT;    AMSR-E;    AMSR2;   

DOI  :  10.1016/j.rse.2019.04.022

来源: Elsevier

【 摘 要 】

Global estimation of Gross Primary Production (GPP) - the uptake of atmospheric carbon dioxide by plants through photosynthesis - is commonly based on optical satellite remote sensing data. This presents a source driven approach since it uses the amount of absorbed light, the main driver of photosynthesis, as a proxy for GPP. Vegetation Optical Depth (VOD) estimates obtained from microwave sensors provide an alternative and independent data source to estimate GPP on a global scale, which may complement existing GPP products. Recent studies have shown that VOD is related to aboveground biomass, and that both VOD and temporal changes in VOD relate to GPP. In this study, we build upon this concept and propose a model for estimating GPP from VOD. Since the model is driven by vegetation biomass, as observed through VOD, it presents a carbon sink driven approach to quantify GPP and, therefore, is conceptually different from common source-driven approaches. The model developed in this study uses single frequencies from active or passive microwave VOD retrievals from C-, X- and Ku-band (Advanced Scatterometer (ASCAT) and Advanced Microwave Scanning Radiometer for Earth Observation (AMSR-E)) to estimate GPP at the global scale. We assessed the ability for temporal and spatial extrapolation of the model using global GPP from FLUXCOM and in situ GPP from FLUXNET. We further performed upscaling of in situ GPP based on different VOD data sets and compared these estimates with the FLUXCOM and MODerate-resolution Imaging Spectroradiometer (MODIS) GPP products. Our results show that the model developed for individual grid cells using VOD and change in VOD as input performs well in predicting temporal patterns in GPP for all VOD data sets. For spatial extrapolation of the model, however, additional input variables are needed to represent the spatial variability of the VOD-GPP relationship due to differences in vegetation type. As additional input variable, we included the grid cell median VOD (as a proxy for vegetation cover), which increased the model performance during cross validation. Mean annual GPP obtained for AMSR-E X-band data tends to overestimate mean annual GPP for FLUXCOM and MODIS but shows comparable latitudinal patterns. Overall, our findings demonstrate the potential of VOD for estimating GPP. The sink-driven approach provides additional information about GPP independent of optical data, which may contribute to our knowledge about the carbon source-sink balance in different ecosystems.

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