Table 1. Meteorological factors during the sampling period and the major ion concentrations in the wet depositions along the cruise tracks
[i] Note: Wind speed, direction and temperature are the mean values of each sampling campaign.
[ii] SN, Sample number; WS, wind speed; WD, wind direction; T, temperature.
Table 2. Major ion concentrations in the wet depositions collected in different areas (in µeq L−1)
[i] Note: Coefficients of variation of the observed ions range from 84 to 132%, suggesting that standard deviations are large compared to the means. In this case, the mean is not a good statistical description of the results, whereas the median could better depict the typical outcome.
[ii] na, not available.
[iii] a Cv, coefficient of variation, is the ratio of the standard deviation to the mean.
Fig. 1.
Contribution percentages of each ion to total ionic concentrations, in µeq L−1.
Fig. 2.
Ionic concentrations in the samples collected in both Northern Hemisphere and Southern Hemisphere, in µeq L−1. Error bars are the standard deviations.
Fig. 3.
Enrichment factors of ions in wet depositions. Error bars represent the standard deviation of the 22 observed samples. The values of and are not available because of their greatly varied concentrations in seawater; consequently, the typical ratios of /Na+ and /Na+ cannot be given.
Table 3. The correlations between concentrations of marine-sourced ions (Cl−, Na+, K+ and Mg2+) and Ca2+ and in the wet deposition on an equivalent basis (n=22)
[i] Note: The upper right part of the table is the correlation coefficient, and the lower left part is the significance.
[ii] *Correlation is significant at the 0.05 level (two-tailed).
[iii] **Correlation is significant at the 0.01 level (two-tailed).
Fig. 4.
Ionic loadings in the two components extracted by principal component analysis. The raw data were normalised through log transformation. Varimax with Kaiser normalisation rotation method was used to highlight the main influence factors, and regression method was selected to calculate factor score coefficient. Consequently, two components were extracted, and the horizontal and vertical axes were represented as the loadings of the eight observed variables in component 1 and component 2, respectively. The loadings were obtained from the eigenvalues of the two components and their corresponding eigenvectors.
Fig. 5.
Correlation analysis between wind speed and marine-sourced ions, Cl−, Na+, K+ and Mg2+.
Fig. 6.
Air mass backward trajectories of four typical precipitation events at heights of 500, 1000 and 1500 m, respectively. The backward trajectories were obtained with the aid of NOAA HYSPLIT model. Figures a, b, c and d are illustrated for sample no. 2, 9, 18 and 14, respectively. The date on each figure denotes the ending date of the total running time, namely, the sampling time.
