Supplementary Material to the article:
“Temperature, Extreme precipitation and Diurnal Rainfall Changes in the urbanized Jakarta city during
the past 130 years”
Submitted to International Journal of Climatology
Siswanto et al.
siswanto@knmi.nl
Data Quality on Temperature and Hourly Precipitation
1. Diurnal Temperature Range as a testing parameter to check temperature data homogeneity
Tmin.
The diurnal temperature range (DTR) is the difference between daily maximum temperature (Tmax)
and daily minimum temperature (Tmin). In the main paper, homogeneity tests have been applied to
temperatures of Jakarta Obs. (see detail description in Section 2 paragraph 6&7 on page 7). The
motivation of using the homogeneity check is to obtain a valid assessment of a linear trend from annual
temperature series. It is recommended to test the annual or monthly series first before testing the
corresponding daily series because daily series are much noisier and thus more difficult to test for
changepoints1. The result of applying the RHtestV4 on Jakarta annual temperature is shown in Figure
S1. The obtained linear trend from different adjusted temperature in regards to the different period for
Tmean and Tmin show a different trend coefficient.
Fig. S2 shows the time series of annual averaged DTR for Jakarta. From 1866 to 1991/1992 the series
is generally homogeneous. An obvious break point (shift) is detected somewhere between 1991/1992
and 1997. We do not have any metadata explaining this shift. To verify whether the shift is an
instrumental issue or related to a climatic oddity, we plot also annual DTR from Cengkareng and
Semarang observations. Cengkareng is a station close to Jakarta, while Semarang is somewhat further
away. We find parallel decreasing trends in these station after the early 1980s (which is the time data is
available for the two reference stations). This analysis indicates a climatic cause of the general decrease
in DTR. The sudden drop in DTR for Jakarta Obs. in 1997 is not shared by the surrounding stations.
We observe that the drop in DTR relates to a significant drop in Tmax during this year as can be seen in
Fig. 1 top panel.
1
see the RHtestV4 manual at
http://etccdi.pacificclimate.org/RHtest/RHtestsV4_UserManual_20July2013.pdf
Fig. S1. [top panel] The adjusted annual mean temperature series after homogenization test for
Tmax, Tmean, and Tmin series of Jakarta observatory using RHtestsV4. [bottom panel] The
example of homogenization check for annual mean minimum temperature series of Jakarta
observatory using RHtestsV4.
Fig. S2. The diurnal temperature range series from unadjusted daily series of Tmax and Tmin of
Jakarta Obs. The available time series from Cengkareng Airport and Semarang are included to
verify the decreasing DTR after 1980s.
2. Diurnal Cycle of Temperature in the period 1991-1999
The diurnal temperature cycle series of Jakarta Obs. is depicted as the hourly evolution of
temperature during daily course. A 10 years averaged diurnal cycle is calculated to show the
decadal changes from the period 1871-1880 to 2001-2010. However, 2 decades are
missing; the period 1981-1990 and 1991-2000. To verify whether the increase of
nighttime temperature and the gradual increase of daytime temperature are consistent
during these missing decades, we use instantaneous temperature measurements at 07LT,
13LT and 18LT during the period 1991-1999. Those instantaneous temperatures were obtained
from daily meteorological summary report (FKLIM) from Jakarta Obs. and neighboring
stations. These data have been plotted together with the changes in the diurnal cycle of Jakarta
Observatory depicted in Fig.S3. The plot confirmed that the average of 1991-1999 period from
the stations in the most urbanized city center (Jakarta Obs. and Tanjung Priok) in parallel with
the gradual changes of diurnal cycle of Jakarta Obs. temperature, while temperatures at the
places that are less or later urbanized are changing at slower rate. Thus, we believe that our
diurnal cycle of temperature plot in Fig. 9 is still robust. This confirmation is also inline with
our analysis result in Fig. 4 in the manuscript.
Fig. S3. The 10 years averaged diurnal cycle changes of Jakarta Obs. hourly temperature from the
period 1871-1880 to 2001-2010. The instantaneous temperature records at 07LT, 13LT, 18LT from
neighboring stations are included to check the changes during the period 1991-1999.
3. Diurnal Cycle of Precipitation in the period 1991-1999 and comparison with the diurnal cycle in
precipitation from more rural areas.
Similar to the case of diurnal temperature cycle series of Jakarta Obs hourly precipitation record
during the period 1991-1999 for Jakarta Obs are unfortunately not available. As an alternative, we
used the closest available data from Cawang (~9 km from old BMKG and ~14 km from the new
BMKG headquarter). The hourly records are obtained from automatic rain gauge (Hellman type)
that available for 2 years observation 1998-1999 and is shown in Fig. S4 top panel. An uncertainty
range is added relating to one-standard deviation. The Cawang 1998-2000 diurnal cycle exhibits a
similar diurnal and hourly pattern with the later period diurnal cycle characteristics of Jakarta Obs.
However, the peaks in the morning and evening rainfall are lower in the Cawang station.
Interesting is that the afternoon peak in Cewang is earlier than in Jakarta Obs. Using similar
analysis, a comparison of Jakarta diurnal cycle with Bogor and Sukabumi is shown in Fig. S4
bottom panel. Sukabumi indicate a diurnal pattern with consistent afternoon peak, while Bogor
shows an afternoon till evening rainfall peak. Bogor (265 m a.s.l) is separated about 55 km from
Jakarta, while Sukabumi (600m a.s.l) has a disctance at 106 km away. Both cities are close to the
mountainous areas that might have different type of climate and diurnal cycle.
Fig. S4. (top panel): The 10 years averaged diurnal cycle changes of Jakarta Obs. hourly rainfall
from the period 1900-1910 to 2001-2010 and the diurnal cycle from Cawang stations during 19982000 available records is included to confirm the changes during the gap period 1991-2000. Both
stations are separated at a distance of 14 km within the city of Jakarta. (bottom panel): The 10
years averaged diurnal cycle changes of Jakarta Obs. hourly rainfall from the period 1900-1910 to
2001-2010 and the diurnal cycle from Sukabumi and Bogor (West Java) stations during 1993-2006
and 2010-2013 available records, respectively.