2.4 Scaling of carbon fluxes by Modelling techniques 
Carbon dioxide (CO;) is a major greenhouse gas and its rapid 
increase in the atmosphere after the pre-industrial time is the 
cause of recent time global warming and climate change (IPCC 
reports 1995). Much of the current increasing trend of CO; is 
attributable to the 6-fold increase in human use of fossil fuel, 
deforestation and other anthropogenic activities. Of the total 
anthropogenic CO, emission, only 30 - 40% remains in the 
atmosphere and the rest is being absorbed by ocean and 
terrestrial biosphere (IPCC reports 1995). While anthropogenic 
release of CO, is continuously increasing at a rapid rate, 
sinking strength of the natural system: terrestrial biosphere and 
ocean is decreasing (Berthelot et al., 2005). Thus controlling 
the growth rate of atmospheric CO; by reducing the 
anthropogenic CO, release and helping natural system for 
enhancing uptake capacity of atmospheric CO, is a major 
challenge. 
There have been a few studies on assessing spatial and 
temporal patterns of satellite based biophysical parameters and 
NPP over India. Estimates of monthly net C fixation and net 
primary productivity over India and its eight regions, using 
SPOT-VEGETATION 10-day NPP composites, and comparing 
the monthly patterns of NPP and NDVI was made (Chhabra 
and Dadhwal, 2004).The total net C fixation of India was 
estimated as 2.18 PgC, which amounts to area-weighted 
terrestrial NPP of 6.66 tCha™ yr! for the period June 1998 
May 1999. An analysis of monthly fAPAR dataset derived 
from NOAA-AVHRR data covering the period from July 1981 
to May 2001 over the Indian land mass was carried out (Pandya 
et al., 2004). 
2.4.1 Measurement through ground base network over 
India 
For quantitative understanding of regional CO, transport and its 
variations with regional environmental boundary condition 
different spatial and temporal scales have to be analysed 
through field measurements. The distributed dense networks of 
observations would be useful to represent the CO, changes due 
to geographic and local environmental conditions. NCP is 
making continuous efforts towards multiplying ground based 
net work across the country by installing sensors for measuring 
boundary layer atmospheric CO,, flux towers for measuring the 
CO, flux exchanges between selected ecosystems and 
atmosphere. 
Under this program, Vaisala CARBOCAP GMP343 is installed 
at six stations and some are under plan. The Vaisala 
CARBOCAP GMP343 is an accurate and rugged probe type 
instrument that can measure atmospheric CO, with acceptable 
compromise between size, response time accuracy and stability. 
Analysis of data obtained from Dehradun station for the year 
2009 was done (Sharma et al, 2011) and work is under 
progress for other stations. The data at Dehradun exhibit 
distinct diurnal and semi-annual cycles. CO; decreases during 
sunrise to afternoon and increases during afternoon to sunset. It 
remains higher during the night time. The semi-annual cycle 
has decreasing phase during Feb-March and July-Sep, and has 
increasing phase during rest of the period. This observed 
variability of atmospheric CO, is mostly driven by local 
ecosystem activity. 
2.4.2 Analysis of satellite measured atmospheric CO2 
Recently several space based observation programs such as 
Atmospheric Infra Red Sounder (AIRS), SCanning Imaging 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
Absorption spectro Meter for Atmospheric CartograpHY 
(SCHIAMACHY), Greenhouse gases Observing SATellite 
(GOSAT).AIRS can measure CO, at mid troposphere while 
SCHIAMACHY and GOSAT can measure columnar 
atmospheric CO,. We have analyzed the data obtained from 
these satellite observations over India and surrounding oceans 
and tried to link with surface fluxes (source and sink). Since 
AIRS provides observations since 2002 till now, this data has 
been extensively used for analysis (Nayak et al., 2011). An 
increasing rate mid tropospheric CO, is 2.14 ppmv yr! is 
observed, which is almost the same as that of observed CO, at 
Maunaloa. 
The annual cycle has larger amplitude over the land than over 
the oceans. There also exist inter-annual variations in the 
observation. In order to understand the causes of such 
variability, we have computed fluxes of CO; exchanges over 
the land (India) and over the oceans through integrating 
different data bases (remote sensed and observed) in to 
different models developed in the recent past for the purpose. 
The description of the modelling approach followed is provided 
in Nayak et al., 2011. On inter-annual scale, flux exchanges 
over the tropical north Indian Ocean could play positive role on 
the control of atmospheric carbon dioxide growth rate (Nayak 
et al., 2011). 
2.4.5 Modeling NPP, NEP and associated parameters 
related to Carbon Cycle over terrestrial India 
The Carnegie-Ames-Stanford Approach (CASA), a terrestrial 
biosphere model, has been used to investigate spatiotemporal 
pattern of net primary productivity (NPP) during 2003 over the 
Indian subcontinent. Sensitivity analysis suggest that the 
difference could be due to inclusion of variable light use 
efficiency (LUE) across different land cover types and 
environment stress scalars as down regulator of NPP in the 
present CASA model study.(Nayak et al., 2011). 
Recently we have also implemented CASA model to simulate 
NPP, NEP, soil respiration etc. over India at 2x2 min spatial 
resolution. In the national scale, average annual NPP is 
estimated to be 1.5 Pg C Yr' and is increasing at the rate of 
0.005 Pg C Yr? during past 25 years from 1981-2006. This 
trend is equivalent to 8.596 over the country during past 25 
years. 
This increase is primarily due to the enhancement of 
productivity over agricultural lands in the country. Variability 
of precipitation has stronger role on the control of inter-annual 
variability of NPP. Spatial distribution of NPP trend is 
different in different places and in different periods. In the 
recent time (1995 onwards), large decline of NPP over the 
Indo-Gangetic plane is observed owing to decline of rain over 
the regions. Estimated NEP budget for the country suggest that, 
on an average India is the region of net sink of atmospheric 
CO, with total annual uptake of 9.5 Tg C yr'. There exists 
strong inter-annual variability of NEP over the country. Except 
early period (1981-1985), most of the years India is net sink of 
atmospheric CO;. 
2.5 Estimation and modeling of geochemical C-fluxes- 
weathering, wetland  effluxes, sediment erosion and 
deposition, riverine and coastal C-flows. 
Geochemical fluxes, comprising of variety of processes, though 
much smaller in magnitude comprise important fraction of 
    
    
     
   
   
   
   
   
   
    
  
    
  
   
   
    
   
    
   
   
  
  
   
  
  
   
   
    
  
  
    
  
     
   
    
   
   
   
     
   
   
   
   
   
   
   
   
   
   
    
    
      
        
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