Statistics (BNPB 2019) indicate that between 2010-2018 around 87% of all natural disasters in Indonesia were related to hydrometeorology. The region is primarily associated with high rainfall accumulation. However, rainfall intensity regularly fluctuates and seasonal droughts do occur (Bonal et al. 2016). In the Maritime Continent, droughts can be attributed to a narrower Intertropical Convergence Zone (ITCZ) during some periods (Xavier et al. 2020). There is also a strong connection between droughts and Indonesian fires with type of El Niño and phase of the Indian Ocean Dipole (Pan et al. 2018). According to Meteorology, Climatology, and Geophysical Agency (BMKG), in Indonesia in 2019, about 92% of the country was experiencing drought due to El Niño cycle at the end of 2018 (Indonesian Red Cross, 2019).
BNPB, 2019: Indonesian National Agency for Disaster Countermeasure (Badan Nasional Penanggulangan Bencana (BNPB)). http:/bnpb.cloud/dibi/tabel1b (Accessed March 15, 2019).
Bonal, D., B. Burban, C. Stahl, F. Wagner, and B. Hérault, 2016: The response of tropical rainforests to drought—lessons from recent research and future prospects. Ann. For. Sci., https://doi.org/10.1007/s13595-015-0522-5.
Xavier, P., and Coauthors, 2020: Seasonal Dependence of Cold Surges and their Interaction with the Madden–Julian Oscillation over Southeast Asia. J. Clim., https://doi.org/10.1175/jcli-d-19-0048.1.
Pan, X., M. Chin, C. M. Ichoku, and R. D. Field, 2018: Connecting Indonesian Fires and Drought With the Type of El Niño and Phase of the Indian Ocean Dipole During 1979–2016. J. Geophys. Res. Atmos., https://doi.org/10.1029/2018JD028402.
Meteorological drought is a condition in which rainfall has decreased compared to the average. Hydrological drought occurs when low water supply becomes evident.
Different definitions which were applied to the rainfall data are described below.
Drought_1 (BMKG's definition)
Currently, in drought monitoring, Agency for Meteorology, Climatology and Geophysics of the Republic of Indonesia (BMKG) uses an idicator called "No Rain Day" (HTH). HTH is a series of days where there is no rain in a row which is counted back from the date of monitoring.
(1) 1-5 Very short
(2) 6-10 Short
(3) 11-20 Moderate
(4) 21-30 Long
(5) 31-60 Very long
(6) >60 Extreme drought
Following this definition, each day is classified and the number is assigned (from 1 to 6). This definition seems to be problematic regarding NaN values (missing data). It requires continuous dataset - even one day of missing data stops the counting. This is not the case of Drought_2 and Drought_3 definitions - when calculating a 10-days moving average, NaN values are ignored.
First, a 10-day moving average of daily accumulated precipitation ("daily_aw") is calculated. This technique is helpful to detect longer droughts. Then, "drought days" are defined as days ("daily_aw") with accumulated precipitation being less than the 10th percentile of daily precipitation. For calculating percentiles, only days with precipitation > 1 mm/day are considered. The final output is daily accumulated precipitation (not a 10-day moving average).
First, a 10-day moving average of daily accumulated precipitation ("daily_aw") is calculated. This technique is helpful to detect longer droughts. Then, "drought days" are defined as days ("daily_aw") with accumulated precipitation being less than the 5th percentile of daily precipitation. For calculating percentiles, only days with precipitation > 1 mm/day are considered. The final output is daily accumulated precipitation (not a 10-day moving average).
Each filename is composed of WMO number, definition used, and info if these are values or a time series vector related to values.
# missing data
If you see 8888 in the values, it means "Unmeasured Data"
NaN and 9999 refer to "No Data"
In raw data, time series vector is continous even if there is missing data.
# data availability
Whenever possible, timespan was set for all available days between 1 January 2000 - 31 December 2020.
Data is a classification number from 1 to 6 (Drough_1) or in mm/day (Drough_2, Drough_3).