ISPRS Archives XXXVIII-8/W3 Workshop Proceedings: Impact of Climate Change on Agriculture 250 MEASUREMENT AND SCALING OF CARBON DIOXIDE (CO2) EXCHANGE IN WHEAT USING FLUX-TOWER AND REMOTE SENSING
نویسندگان
چکیده
The present study investigates the characteristics of CO2 exchange (photosynthesis and respiration) over agricultural site dominated by wheat crop and their relationship with ecosystem parameters from MODIS. Eddy covariance measurements of CO2 and H2O exchanges was carried out at 10Hz interval and fluxes of CO2 were computed at half-hourly time steps. The net ecosystem exchange (NEE) was partitioned into gross primary productivity (GPP) and ecosystem respiration (Re) and integrated daily to derive seasonal course of CO2 exchange over wheat. Diurnal pattern in Net ecosystem exchange (NEE) reveals negative NEE during day-time representing CO2 uptake and positive during night as release of CO2. The amplitude of the diurnal variation in NEE increased with growth of wheat and reached its peak around the anthesis stage. The mid-day uptake during this stage was around 1.15 mg CO2 m s and night-time release was around 0.15 mg CO2 m s. Large daily GPP above 30 g CO2 m d continued until mid of anthesis stage (15 march) and decline rapidly during maturity stage. Linear and non-linear least square regression procedures were employed to develop phenomenological models and empirical fits between flux tower based GPP and NEE with satellite derived variables and environmental parameters. Enhanced vegetation index was found significantly related to both GPP and NEE. However, NDVI showed little less significant relationship with both GPP and NEE. Furthemore, temperature-greenness model combining scaled EVI and LST was parameterized to estimate daily GPP over dominantly wheat crop site. (R = 0.77). Multi-variate analysis shows that inclusion of LST or air temperature with EVI improved variance explained in daily NEE and GPP. ∗ [email protected]
منابع مشابه
Remote sensing of surface energy fluxes at 10-m pixel resolutions
[1] Many applications exist within the fields of agriculture, forestry, land management, and hydrologic assessment for routine estimation of surface energy fluxes, particularly evapotranspiration (ET), at spatial resolutions of the order of 10 m. A new two-step approach (called the disaggregated atmosphere land exchange inverse model, or DisALEXI) has been developed to combine lowand high-resol...
متن کاملScaling Gross Primary Production (GPP) over boreal and deciduous forest landscapes in support of MODIS GPP product validation
The Moderate Resolution Imaging Radiometer (MODIS) is the primary instrument in the NASA Earth Observing System for monitoring the seasonality of global terrestrial vegetation. Estimates of 8-day mean daily gross primary production (GPP) at the 1 km spatial resolution are now operationally produced by the MODIS Land Science Team for the global terrestrial surface using a production efficiency a...
متن کاملScaling Flux Tower Observations of Sensible Heat Flux Using Weighted Area-to-Area Regression Kriging
Sensible heat flux (H) plays an important role in characterizations of land surface water and heat balance. There are various types of H measurement methods that depend on observation scale, from local-area-scale eddy covariance (EC) to regional-scale large aperture scintillometer (LAS) and remote sensing (RS) products. However, methods of converting one H scale to another to validate RS produc...
متن کاملUsing Stochastic Ray Tracing to Simulate a Dense Time Series of Gross Primary Productivity
Eddy-covariance carbon dioxide flux measurement is an established method to estimate primary productivity at the forest stand level (typically 10 ha). To validate eddy-covariance estimates, researchers rely on extensive time-series analysis and an assessment of flux contributions made by various ecosystem components at spatial scales much finer than the eddy-covariance footprint. Scaling these ...
متن کاملScalar flux profile relationships over the open ocean
[1] The most commonly used flux-profile relationships are based on Monin-Obukhov (MO) similarity theory. These flux-profile relationships are required in indirect methods such as the bulk aerodynamic, profile, and inertial dissipation methods to estimate the fluxes over the ocean. These relationships are almost exclusively derived from previous field experiments conducted over land. However, th...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2009