T.A. Cinco et al. / Atmospheric Research 145–146 (2014) 12–26
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Fig. 5. Trends in the frequency of days with minimum temperature in the Philippines (1951–2010) below the 1961–1990 mean 1st percentile (cold nights).
trends for both an increase in hot days and decrease in cold
nights. The stations at Alabat, Virac and Legaspi which are
located on the Pacific coast within 200 km of one another, in an
area known as the Bicol region, show a significant decrease in
hot days which could be considered as a small cooling trend
cluster. From approximately 8°N to 13°N there is a line of five
stations on the Pacific coast (Catamaran, Hinatuan, Surigao,
Catbalogan and Tacloban) which all exhibit statistically
significant increase in hot days with the station at Tacloban
showing a particularly high increase. Other than this, there
does not appear to be a discernible national level spatial
pattern for either cold day or hot night indices.
A significant increase in hot days is also found at the station
in Baguio and this was also the case in both the other reference
studies which used data from this station in earlier observations
of the same indicator (Griffiths et al., 2005; Manton et al., 2001).
This station is also one of two stations (the other is Malaybalay)
located in an upland area, both of which show large significant
trend increases which perhaps provides an indication that
elevation does not play an influential constraining role in
temperature extreme indices. However, the recent urbanisation
of most of the cities in which the stations used in this study are
located means we must use caution when considering these
results as definitive.