Theo BrandsmaKNMI, the Netherlands

International workshop on the digitization of historical climate data

the new SACA&D databases and climate analysis in the Asian region

Citeko, Bogor, Indonesia, 2-5 April 2012

Daily Indonesian rainfall in the 1879–1916 period

2

1. Obtaining knowledge of the rainfall climate in Indonesia

2. Design of irrigation systems

3. Planning of agricultural crops

4. Planning of infrastructural works like railways

Reasons for setting op a rainfall network

Background

3

Growth of the network

4

Growth of the network

Number of stations with daily rainfall (1879-1916)

5

Distribution of the stations in 1879 (124 stations)

Growth of the network

6

Distribution of the stations in 1900 (225 stations)

Growth of the network

7

Standardization

8

Standardization

Rain gauge

1. Rim at 1.2 m above ground level

2. Diameter of 12 cm

3. Vessel containing 275 mm

9

Standardization

Regulation examples

1. Following the orders of the director of the Batavia

observatory concerning the positioning of the rain gauge

2. Measuring of rainfall each morning at 6, 7, 8, or 9 local time

and assigning it to the day of measurement on specially

prepared measurement forms

3. Rounding the measurements to whole mm

4. Sending two duplicates of the daily measurements to

Batavia/Jakarta right after the end of a month by two

subsequent postal deliveries (and keeping the original for

another six months)

5. Publishing monthly summaries in the Javasche Courant en

the daily values in the annual rainfall books (by the director)

10

Digitization and quality control

11

Digitization and quality control

Example from the yearbooks

1.Scanning2.OCR3.Quality control4.Database

12

― means no rain

n.w. means not measured

* means multi-day amount

† means measuring period not exactly 24 hours

w.o. means incomplete measurement, monthly totals could

not be calculated

Possible codes

Digitization and quality control

13

•

Digitization and quality control

Example page

14

Final goal: to import the 1879-1916 daily rainfall series in SACA&D

Digitization and quality control

15

1. Extreme-value analysis

2. Studies of climate change and variability

3. Validation of climate models

Possible applications of the dataset

Applications

16

Terima Kasih