## 3 Results and Discussion
### The Literature and References
#### 3.5.2 Reference Analysis  
Citation analysis involves examining the references of articles within the BCL dataset. If a reference receives substantial citations within this dataset, it indicates a significant impact on the field's progress. These references may be within the BCL dataset or beyond it. CiteSpace facilitates segmenting the dataset's references by time. We used a time slice of three years, selecting only the top six to seven most cited references within each slice, and limiting the discussion to references published after 2000. Table S8 lists the detailed information of the top 20 most cited references in the BCL dataset, highlighting the field's most influential works.  
Figure 8 shows the network graph of references, with each node representing a reference. Notably, some references overlap with articles in Figure 7, such as those of [PERSON] (2001) [24], [PERSON] and [PERSON] (2008) [52], and [PERSON] et al. (2013) [6], which are prominent in the high-citation references of the BCL database. Additionally, there are relatively recent references within the BCL dataset, which might not be prominently highlighted when sorted by total citations due to their recency. A time-slice approach, however, allows for the highlighting of these references, as observed with [PERSON] et al. (2012) [21],  
[PERSON] et al. (2016) [22], [PERSON] et al. (2020) [8], and others. For instance, [PERSON] et al. (2020) [8] conducted a comprehensive review on black carbon, emphasizing the measurement of black carbon in snow and ice, historical records in ice cores, spatial distribution, and effects on the cryosphere. The study analyzed the radiative forcing and associated effects of black carbon in snow and ice, as well as its role in cryosphere melting. The research revealed that black carbon concentrations are lower in polar regions but higher in mid-latitude areas and melting regions of mountain glaciers, exerting a greater influence on the melting process.  
Moreover, there are additional references outside the BCL dataset that offer substantial support for the articles within it. Detailed information about these references can be obtained through additional searches on the Web of Science (WOS) database. Among them, the top three most cited references are the studies of [PERSON] et al. (2020) [114], [PERSON] et al. (2017) [67], and [PERSON] et al. (2018) [113]. [PERSON] et al. [114] provides details of the features of the ERA5 global reanalysis, which records detailed global atmospheric, land surface, and oceanic wave conditions since 1950. ERA5, compared to its predecessor ERA-Interim, features significantly improved horizontal resolution, more frequent data output, and enhanced predictive capabilities. [PERSON] et al. (2017) [67] provides an overview of the MERRA-2 system and various performance metrics. As an upgrade to MERRA, MERRA-2 enhances atmospheric reanalysis data quality for climate scientists by incorporating new observational data and improving models. This enhancement is crucial for understanding climate change, conducting climate model research, and formulating environmental policies. [PERSON] et al. (2018) [112], employing emission inventories and index decomposition analysis, quantifies the trends in anthropogenic emissions in China from 2010 to 2017. The study highlights emission control measures as the primary driver for emission reduction. It estimates that between 2013 and 2017, China's anthropogenic emissions decreased by 59% for SO\({}_{2}\), 21% for NOx\({}_{x}\), 23% for CO, 36% for PM\({}_{10}\), 33% for PM\({}_{2.5}\), 28% for black carbon (BC), and 32% for organic carbon (OC). Exploring these references outside the BCL dataset offers a broader perspective on black carbon research in the meteorological realm.