## 5 Discussion  
Spatial Patterns of Extreme High CO\({}_{2}\) Concentrations during El Nino Southern Ocillation (ENSO) Events  
In order to examine the potential influence of El Nino Southern Ocillation (ENSO) events during the periods of high values of extreme XCO\({}_{2}\) grids number shown in Figure 6, we displayed the mean Z score of GM-XCO\({}_{2}\) during July-September 2010 (Figure 9a) and March-May 2016 (Figure 9b). A high Z score indicates a strong likelihood of a high XCO\({}_{2}\). During July-September 2010, high Z scores were concentrated over western Russia detected as Ex-1. High temperature, burned area, and drought occurred over western Russia in the 2010 summer, which is consistent with results from prior research on strong CO\({}_{2}\) release [15; 16; 72]. The XCO\({}_{2}\) anomalies from 2009 to 2010 over this region previously identified from the GOSAT observations [26]. As the \(\Delta\)Temp, scPDSI, and \(\Delta\)GPP shown in Figure 9c,e,g, significant high temperature, severe drought and reduced GPP happened over western Russia, which is consistent with the high XCO\({}_{2}\) shown in (a). The detected Ex-1 (the biggest one) shown in Section 4.1 cover these area and period. While, the range of Ex-1 covers most of this latitude, that could be the result of atmospheric transport, and effect of drought-induced CO\({}_{2}\) emissions in eastern Eurasia, discussed in [PERSON] et al. [73]. The small region of high XCO\({}_{2}\) in eastern North America is not associated with a high temperature or drought event. That high XCO\({}_{2}\) is possible due to reduced GPP over that region shown in (g) or/and a result of the transport and dilution of the Eurasian anomaly as described in [PERSON] et al. [26]. During March-May 2016, high Z scores occurred generally over tropical land areas, detected as Ex-2, Ex-3, Ex-4, Ex-6 and Ex-10, and the influenced grids exceed that in summer 2010, which indicated that affected areas were more widespread. This shows the influence of the extreme El Nino of 2015-2016 [19; 74; 75]. Although, CO\({}_{2}\) release over some area was well been evaluated [22; 26], there  
Figure 8: Detected results of extreme high XCO\({}_{2}\) grids number with different emission increases added to the input CO\({}_{2}\) flux, from 1 July to 31 September 2009, described in Section 3.3. Temporal statistical grid number is shown in (**a**), and spatial distribution of detected emission ratio is shown in (**b–e**). Corresponding changed XCO\({}_{2}\) are shown in Figure S3. (**a**) Time series of influenced grids of various increases in biospheric CO\({}_{2}\) fluxes as percentages added as emission; (**b**) detected grids with 25% CO\({}_{2}\) flux as emission; (**c**) detected grids with 37.5% CO\({}_{2}\) flux as emission; (**d**) detected grids with 50% CO\({}_{2}\) flux as emission; (**e**) detected grids with 62.5% CO\({}_{2}\) flux as emission. are some high XCO\({}_{2}\) regions that have not been examined in great detail in the literature, such as southern South America and Australia. We can find extreme high temperature, severe drought and reduced GPP shown in eastern South America, southern Africa, Australia and southeastern Asia, shown in Figure 9d,f,h. Extreme high XCO\({}_{2}\) and low temperature, wet scPDSI conditions and reduced GPP shown in southern South America, which could be induced by the worst flood in decades ([PERSON] et al., 2016). The high XCO\({}_{2}\) of detected Ex-6 could be contributed by both drought in mid-South America and flooding in southern America. In addition, Ex-5 over bare land was detected, with less local CO\({}_{2}\) flux in response to climate change ([PERSON] et al., 2016). It could be a result of local soil respiration increase and CO\({}_{2}\) diffusion from nearby area like India and south-eastern Asia. High temperature in western North America during springtime can contribute to vegetation growth, which has little effect on CO\({}_{2}\) increase.