# Designing an Interactive Visual Analytics System for
## 6 Case Studies
### Case Study: Performing a Comparative Analysis on Multiple Regions  
For the second case study, we conducted a comparative analysis using the designed system across multiple geographically distributed regions in the United States. Six locations were selected based on the availability of long-term, high-resolution hourly precipitation data: Los Angeles International Airport (LAX, CA), Chicago Ohare International Airport (ORD, IL), Kansas City International Airport (MCI, MO), Houston Intercontinental Airport (IAH, TX), Washington Reagan National Airport (DCA, VA), and Seattle (WA). These stations were selected because each provides more than 50 years of hourly precipitation records. Figure 14 shows the performed IETD analysis (\(\theta=2\)) of all six stations over 50 years from 1972 to 2022.  
Among them, Los Angeles (LA) showed distinctive precipitation patterns because it follows a Mediterranean climate pattern, characterized by hot, dry summers and cool, wet winters. The visualization revealed that LA had extremely low rainfall amounts compared to other stations. This pattern is consistent with Southern California's semiarid climate, where precipitation predominantly occurs between November and March [83]. In contrast, Seattle recorded substantially more precipitation than LA, but still less precipitation than the other stations. As winter is the wettest season, and July is the driest month in Seattle, high spikes were observed in winter. Seattle's precipitation pattern is broadly known as it follows the classic Pacific Northwest maritime climate [84], with persistent light to moderate rainfall rather than the high-intensity events characteristic of other regions.  
Kansas City and Chicago showed similar precipitation patterns, although Chicago typically sees more snowfall than Kansas City. However, rainfall amounts are slightly higher in Kansas City than in Chicago. Both cities represent continental climate patterns with distinct seasonal precipitation cycles [85,86]. The similarity in the pattern but the difference in intensity highlights the importance of considering geographical transitions from the humid subtropical climate of the southern plains to the continental climate of the Great Lakes region [87; 88; 89]. Similar precipitation patterns were observed when comparing the three weather stations in ORD, DCA, and IAH airports. Chicago (ORD) often showed more precipitation patterns than others. As tropical systems notably influence Houston's (IAH) precipitation regime, significant late summer and early fall maxima corresponding to hurricane season were observed in the visualization. Washington D.C. DCA displays a more uniform precipitation pattern throughout the year, with slight increases during the summer months due to convective activity and occasional tropical system impacts [90].  
By comparing the visualizations of all stations, we immediately observed a precipitation increase in all weather stations since 2013. This observ  
Figure 14: A comparative precipitation analysis across multiple U.S. regions using temporal precipitation visualizations. Six long-term weather stations from geographically distinct locations (1972–2022) are analyzed with the multi-site analysis interface, which allows users to navigate through precipitation data via zooming and panning functions while displaying precise precipitation values for direct regional comparison.  
change projections that suggest increased precipitation intensity in many parts of the United States [9; 50]. The visualizations indicate that it is a robust signal of consistently increasing patterns affecting diverse areas rather than regional variability. For more detailed analysis, we also performed trend analysis, extreme event analysis, and baseline climatology comparison analysis with the designed multi-site analysis interface. A detailed explanation of the performed analysis is included below.