Local climate variability associated to sustainable agriculture at rain shadow areas of mount Rinjani and Tambora in West Nusa Tanggara

Abstract

Climate is driven by solar energy received on the earth surface and local factor, such as mountains. The solar energy affects climate variables namely, temperature, atmospheric pressure, relative humidity, wind and rain. In addition, mountains perform rain shadow areas and affect variability of local climate. A descriptive research was conducted to study variability of those variables associated to direct normal solar irradiation (DNI), and its possible impact on sustainable agriculture at rain shadow areas of Mt. Rinjani in Lombok and Tambora in Sumbawa, West Nusa Tenggara. The results show that the DNI was relative similar at both sides of the Mt. Rinjani which was 13.15±2.6 MJ m−2day−1 on average. While at Mt. Tambora, the DNI at rain shadow area (southern part) was higher than northern part which were 15.6±2.07 MJ.m−2.day−1 and 13.6±3.2 MJ m−2.day−1 respectively. The DNI was relatively high in low lands and it successively decreased through medium and high lands. ETo, air and soil surface temperature were relatively high at rain shadow areas. In conclusion, the intensity of DNI was not significantly affected by aspect factor of incoming light relative to the Mt Rinjani and Mt. Tambora. The mountains had affected the variability of local climate and performed rain shadow areas to the north from Mt Rinjani and to the south from Mt. Tambora, where there had established typical dry land agriculture of semi arid tropics.