Figure 1
From: Ocean acidification may be increasing the intensity of lightning over the oceans
(a) Dependence of LFI on seawater pH adjusted to a constant temperature of 25 °C, and (b) calculated values of pCO2 (calculated from pH and total alkalinity measurements at 25 °C), and (c) Change in LFI with pH and pCO2 from their pre-industrial levels (PIR in the plot) up to pCO2 = 3000 ppm and pH = 7.5, and (d) the ratio of calculated LFIs as a function of predicted atmospheric pCO2 according to RCP 3, 4.5, 6.0 and 8.5 compared to LFI in 2000 at 25 °C. In panels a and b, the different colored markers correspond to different experiments and treatments indicated by + HCl (addition of strong acid experiments) and + CO2 (CO2 bubbling experiments). In addition each data point represents an average of 8–10 repeated measurements of the emission spectra with a standard deviation of ± 4% (maximum). In panel c all data from the 3 CO2 bubbling experiments in the relevant range are included and the black dashed curve indicates the best fit of the logistic model (Eq. 1) to the LFI and corresponding pCO2 data (n = 24).
