Rainfall Rate in Indonesia

The Rainfall Rate is one of the factors used to determine the degree of rain attenuation in the propagation of wireless communications, including satellite communications. Field measurements and recordings for long time periods are the best (empirical) method to know the rainfall rate in a country. Such data can then be used for various calculations concerning signal attenuation caused by rain.

Another way is to depend on models that have been developed by such bodies as the ITU-R Rep. 563-4 and the Global Crane model. Although both models are used to calculate rain attenuation in Indonesia, some experts consider these models not accurate enough, because there were too few samples used when developing the models.

Indonesia is fortunate that further research has been done on this matter with the idea that more accurate models can be constructed. This research has been carried out at 9 locations in the Indonesian archipelago: Jatiluhur, Cibinong, Denpasar, Padang, Surabaya, Bandung, Tanahmerah, Putusibau and Maros. Also one location is in Singapore, i.e. Bukit Timah, which is geographically located in the same position as Indonesia.

Results show that the Rainfall Rate for a 0.01% (R0.01) observation time is as follows (see table).

Table 1.1. R

0.01 Rainfall Rate Measurements in Indonesia

Besides the ITU- and Global Crane model, there exist also the Rice-Holmberg and ESA/ Salonen Baptista models. From the table can be seen that there are significant differences between the results of the field measurements and the calculations using several well-known models.