{'fraction_non_alphanumeric': 0.03304347826086956, 'fraction_numerical': 0.0034782608695652175, 'mean_word_length': 4.877551020408164, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Year-to-year Variations in Reduced Visibility

Visibility observations at four stations in Hong Kong were analyzed. The locations of the four stations, namely the Hong Kong Observatory (HKO), Hong Kong International Airport (HKIA), Cheung Chau (CC) and Waglan Island (WI), are shown in Figure 1. HKO and HKIA are located in the urban area by the side of the Victoria Harbour. CC and WI are outlying islands situated over the southwestern and southeastern side of the territory respectively. Table 1 lists the period and frequency of visibility observations at these stations.