# Influence of Droughs on Mid-Tropospheric CO\({}_{2}\)
## 2 Data  
Tropical Rainfall Measuring Mission (TRMM) precipitation is employed to identify dry and wet years in this paper. TRMM precipitation data (Version 7 3A12) are available from 1998 to the present covering 50\({}^{\circ}\)S-50\({}^{\circ}\)N. The spatial resolution of TRMM precipitation is 0.25\({}^{\circ}\) in latitude and 0.25\({}^{\circ}\) in longitude. TRMM calibrated precipitation data include observations from several different instruments (TMI, AMSR-E, SSM/I, and AMSU-B) ([PERSON] et al., 2016). AIRS Version 5 mid-tropospheric CO\({}_{2}\) mixing ratios ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016) are used in this paper to explore the influence of droughts on atmospheric CO\({}_{2}\). The Vanishing Partial Derivative (VPD) Method ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016) is used to retrieve AIRS mid-tropospheric CO\({}_{2}\) data, which has a maximum sensitivity at 500-300 hPa. The spatial resolution of AIRS CO\({}_{2}\) retrieval is 2\({}^{\circ}\) in latitude and 2.5\({}^{\circ}\) in longitude covering 60\({}^{\circ}\)S to 90\({}^{\circ}\)N. AIRS mid-tropospheric CO\({}_{2}\) data are available from September 2002 to December 2013 and can be downloaded at [[http://disc.sci.gsfc.nasa.gov/AIRS/data-holdings/by-data-product-v5/AIRX3C2M](http://disc.sci.gsfc.nasa.gov/AIRS/data-holdings/by-data-product-v5/AIRX3C2M)]([http://disc.sci.gsfc.nasa.gov/AIRS/data-holdings/by-data-product-v5/AIRX3C2M](http://disc.sci.gsfc.nasa.gov/AIRS/data-holdings/by-data-product-v5/AIRX3C2M)) ([PERSON] et al., 2016). A comparison between AIRS mid-tropospheric CO\({}_{2}\) and convolved INTEX-NA aircraft CO\({}_{2}\) reveals a difference of 0.15 ppm with a standard deviation of 0.71 ppm ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016). AIRS mid-tropospheric CO\({}_{2}\) has also been compared with CONTRAIL aircraft CO\({}_{2}\) and there is a bias of 0.1 ppm with a standard deviation of 1.8 ppm ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016). CO\({}_{2}\) surface fluxes from the biosphere and biomass burning are used to explore CO\({}_{2}\) surface emissions during dry and wet years. The exchange of CO\({}_{2}\) between biosphere and atmosphere from the Carnegie-Ames Stanford Approach (CASA) biogeochemical model ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016) is utilized to explore the biosphere-atmosphere interaction during dry and wet years. The CASA model uses satellite data and a mechanistic plant and soil carbon model to simulate the carbon from the terrestrial ecosystem ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016). Influences of the Normalized Difference Vegetation Index (NDVI), weather, and fire on biosphere are considered in the CASA model ([PERSON] et al., 2016; [PERSON] et al., 2016; [PERSON] et al., 2016). Satellite NDVI data are used to parameterize net primary production in the CASA model ([PERSON] et al., 2016), which calculates the exchange of CO\({}_{2}\) between the atmosphere and biosphere at different time steps and different spatial resolution. Net Ecosystem CO\({}_{2}\) Exchange (NEE), Gross Primary Production (GPP), and ecosystem respiration from the CASA biogeochemical model will be used to explore the influence of droughts on CO\({}_{2}\) fluxes from the biosphere. NEE represents the net exchange of CO\({}_{2}\) between the biosphere and the atmosphere, which is calculated as the difference between ecosystem respiration and GPP. Ecosystem respiration represents the autotrophic and heterotrophic respiration from the biosphere. GPP is related to the carbon uptake by plants during the photosynthesis. CO\({}_{2}\) biomass burning emissions are from Global Fire Emissions Database Version 4.1 (GFEDv4.1) [(40)]. CO\({}_{2}\) emissions from biosphere and biomass burning are available at 0.25 \(\times\) 0.25\({}^{\circ}\) (latitude by longitude). These data are monthly means from 1997 through 2013.