scholarly journals A modeling approach to estimate the gross and net primary production of forest ecosystems as a function of the fraction of absorbed photosynthetically active radiation

2016 ◽  
Vol 8 (2) ◽  
pp. 345-353 ◽  
Author(s):  
A. V. Olchev
Keyword(s):  
Primary Production ◽  
Photosynthetically Active Radiation ◽  
Forest Ecosystems ◽  
Net Primary Production ◽  
Active Radiation ◽  
Modeling Approach ◽  
Absorbed Photosynthetically Active Radiation

scholarly journals The Response of the Amazon Ecosystem to the Photosynthetically Active Radiation Fields: Integrating Impacts of Biomass Burning Aerosol and Clouds in the NASA GEOS ESM 

2021 ◽  
Author(s):  
Huisheng Bian ◽  
Eunjee Lee ◽  
Randal D. Koster ◽  
Donifan Barahona ◽  
Mian Chin ◽  
...  
Keyword(s):  
Primary Production ◽  
Biomass Burning ◽  
Photosynthetically Active Radiation ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Cloud Amount ◽  
Ecosystem Productivity ◽  
Active Radiation ◽  
The Impact ◽  
Fertilizer Effect

Abstract. The Amazon experiences fires every year, and the resulting biomass burning aerosols, together with cloud particles, influence the penetration of sunlight through the atmosphere, increasing the ratio of diffuse to direct photosynthetically active radiation (PAR) reaching the vegetation canopy and thereby potentially increasing ecosystem productivity. In this study, we use the NASA Goddard Earth Observing System (GEOS) model running with coupled aerosol, cloud, radiation, and ecosystem modules to investigate the impact of Amazon biomass burning aerosols on ecosystem productivity, as well as the role of the Amazon’s clouds in tempering the impact. The study focuses on a seven-year period (2010–2016) during which the Amazon experienced a variety of dynamic environments (e.g., La Niña, normal years, and El Niño). The radiative impacts of biomass burning aerosols on ecosystem productivity – call here the aerosol light fertilizer effect – are found to increase Amazonian Gross Primary Production (GPP) by 2.6 % via a 3.8 % increase in diffuse PAR (DFPAR) despite a 5.4 % decrease in direct PAR (DRPAR) on multiyear average. On a monthly basis, this increase in GPP can be as large as 9.9 % (occurring in August 2010). Consequently, the net primary production (NPP) in the Amazon is increased by 1.5 %, or ~92 TgCyr−1– equivalent to ~37 % of the carbon lost due to Amazon fires over the seven years considered. Clouds, however, strongly regulate the effectiveness of the aerosol light fertilizer effect. The efficiency of the fertilizer effect is highest for cloud-free conditions and linearly decreases with increasing cloud amount until the cloud fraction reaches ~0.8, at which point the aerosol-influenced light changes from being a stimulator to an inhibitor of plant growth. Nevertheless, interannual changes in the overall strength of the aerosol light fertilizer effect are primarily controlled by the large interannual changes in biomass burning aerosols rather than by changes in cloudiness during the studied period.

scholarly journals ESTIMATION OF NET PRIMARY PRODUCTION (NPP) USING REMOTE SENSING APPROACH AND PLANT PHYSIOLOGICAL MODELING(PENDUGAAN NET PRIMARY PRODUCTION (NPP) MENGGUNAKAN PENDEKATAN PENGINDERAAN JAUH DAN MODELING FISIOLOGIS TANAMAN)

Agromet ◽  
2008 ◽  
Vol 22 (2) ◽  
pp. 183
Author(s):  
Yon Sugiarto ◽  
Tania June ◽  
Bambang Sapto P
Keyword(s):  
Remote Sensing ◽  
Primary Production ◽  
Net Primary Production ◽  
Remotely Sensed ◽  
Remotely Sensed Data ◽  
Active Radiation ◽  
Value Range ◽  
Use Efficiency ◽  
Absorbed Photosynthetically Active Radiation ◽  
Global Carbon

<p>Information Net Primary Production (NPP) of tropical forests is important for the development of realistic global carbon budgets and for projecting how these ecosystems will be affected by climate changes. This research utilized remotely sensed data and micrometeorological measurement to provide information on vegetation condition. The objective of this research is to estimate spatial NPP using remote sensing approach and plant physiological/micrometeorological modeling. The estimation of NPP is conducted using modeling approach, which is based on relationship between radiation use efficiency, photosyntetically active radiation and fraction of absorbed photosynthetically active radiation by the plants’s canopy. Trend of NDVI derived using micrometeorological measurement showed an increase from 2001 to 2002, and then decrease from 2002 to 2004. Average different values (delta) between both methods used to derive NDVI is relatively constant around 0.33 with a high correlation of r2 = 0.98. Using remotely sensed data, the highest NPP values estimated is in year 2003 with value range between 2000 – 2500 (gC m-2 yr-1), less than 2% of the whole forest area. In 2003, 75% area has NPP between 1500 – 2000 (gC m-2 yr-1), meanwhile for 2002 and 2004 it is only 21% and 50 %, respectively. NPP values estimated using micrometeorological measurement show the increasing of NPP values from 2002 to 2003, and then decrease from 2003 to 2004. There is strong correlation between NPP values derived from the two methods with r2 = 0.98.</p>

scholarly journals The response of the Amazon ecosystem to the photosynthetically active radiation fields: integrating impacts of biomass burning aerosol and clouds in the NASA GEOS Earth system model

2021 ◽  
Vol 21 (18) ◽  
pp. 14177-14197
Author(s):  
Huisheng Bian ◽  
Eunjee Lee ◽  
Randal D. Koster ◽  
Donifan Barahona ◽  
Mian Chin ◽  
...  
Keyword(s):  
Primary Production ◽  
Biomass Burning ◽  
Photosynthetically Active Radiation ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Diffuse Radiation ◽  
Ecosystem Productivity ◽  
Active Radiation ◽  
Fertilization Effect ◽  
The Impact

Abstract. The Amazon experiences fires every year, and the resulting biomass burning aerosols, together with cloud particles, influence the penetration of sunlight through the atmosphere, increasing the ratio of diffuse to direct photosynthetically active radiation (PAR) reaching the vegetation canopy and thereby potentially increasing ecosystem productivity. In this study, we use the NASA Goddard Earth Observing System (GEOS) model with coupled aerosol, cloud, radiation, and ecosystem modules to investigate the impact of Amazon biomass burning aerosols on ecosystem productivity, as well as the role of the Amazon's clouds in tempering this impact. The study focuses on a 7-year period (2010–2016) during which the Amazon experienced a variety of dynamic environments (e.g., La Niña, normal years, and El Niño). The direct radiative impact of biomass burning aerosols on ecosystem productivity – called here the aerosol diffuse radiation fertilization effect – is found to increase Amazonian gross primary production (GPP) by 2.6 % via a 3.8 % increase in diffuse PAR (DFPAR) despite a 5.4 % decrease in direct PAR (DRPAR) on multiyear average during burning seasons. On a monthly basis, this increase in GPP can be as large as 9.9 % (occurring in August 2010). Consequently, the net primary production (NPP) in the Amazon is increased by 1.5 %, or ∼92 Tg C yr−1 – equivalent to ∼37 % of the average carbon lost due to Amazon fires over the 7 years considered. Clouds, however, strongly regulate the effectiveness of the aerosol diffuse radiation fertilization effect. The efficiency of this fertilization effect is the highest in cloud-free conditions and linearly decreases with increasing cloud amount until the cloud fraction reaches ∼0.8, at which point the aerosol-influenced light changes from being a stimulator to an inhibitor of plant growth. Nevertheless, interannual changes in the overall strength of the aerosol diffuse radiation fertilization effect are primarily controlled by the large interannual changes in biomass burning aerosols rather than by changes in cloudiness during the studied period.

scholarly journals Upscaling from Instantaneous to Daily Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) for Satellite Products

2020 ◽  
Vol 12 (13) ◽  
pp. 2083
Author(s):  
Siyuan Chen ◽  
Liangyun Liu ◽  
Xue He ◽  
Zhigang Liu ◽  
Dailiang Peng
Keyword(s):  
Zenith Angle ◽  
Photosynthetically Active Radiation ◽  
Solar Zenith Angle ◽  
Field Measurements ◽  
Area Index ◽  
Active Radiation ◽  
Sensing Applications ◽  
Typical Satellite ◽  
Absorbed Photosynthetically Active Radiation ◽  
Local Noon

The fraction of absorbed photosynthetically active radiation (FAPAR) is an essential climate variable (ECV) widely used for various ecological and climate models. However, all the current FAPAR satellite products correspond to instantaneous FAPAR values acquired at the satellite transit time only, which cannot represent the variations in photosynthetic processes over the diurnal period. Most studies have directly used the instantaneous FAPAR as a reasonable approximation of the daily integrated value. However, clearly, FAPAR varies a lot according to the weather conditions and amount of incoming radiation. In this paper, a temporal upscaling method based on the cosine of the solar zenith angle (SZA) at local noon ( c o s ( S Z A n o o n ) ) is proposed for converting instantaneous FAPAR to daily integrated FAPAR. First, the diurnal variations in FAPAR were investigated using PROSAIL (a model of Leaf Optical Properties Spectra (PROSPECT) integrating a canopy radiative transfer model (Scattering from Arbitrarily Inclined Leaves, SAIL)) simulations with different leaf area index (LAI) values corresponding to different latitudes. It was found that the instantaneous black sky FAPAR at 09:30 AM provided a good approximation for the daily integrated black sky FAPAR; this gave the highest correlation (R2 = 0.995) and lowest Root Mean Square Error (RMSE = 0.013) among the instantaneous black sky FAPAR values observed at different times. Secondly, the difference between the instantaneous black sky FAPAR values acquired at different times and the daily integrated black sky FAPAR was analyzed; this could be accurately modelled using the cosine value of solar zenith angle at local noon ( c o s ( S Z A n o o n ) ) for a given vegetation scene. Therefore, a temporal upscaling method for typical satellite products was proposed using a cos(SZA)-based upscaling model. Finally, the proposed cos(SZA)-based upscaling model was validated using both the PROSAIL simulated data and the field measurements. The validated results indicated that the upscaled daily black sky FAPAR was highly consistent with the daily integrated black sky FAPAR, giving very high mean R2 values (0.998, 0.972), low RMSEs (0.007, 0.014), and low rMAEs (0.596%, 1.378%) for the simulations and the field measurements, respectively. Consequently, the cos(SZA)-based method performs well for upscaling the instantaneous black sky FAPAR to its daily value, which is a simple but extremely important approach for satellite remote sensing applications related to FAPAR.

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