BAM-Net: High Resolution Data for Process Studies in Tropical Dynamics and High Resolution Modeling

The Maritime Continent is a complex system of islands, often with significant topography, deep oceans and shallow seas located in the heart of the Indo-Pacific warm pool. The region is characterized by a very high average daily precipitation, which is modulated by a pronounced diurnal cycle. Precipitation variability in the Maritime Continent region, especially influenced by subseasonal, seasonal and interannual modes, has been of interest to the community as it can easily lead to extreme precipitation events and its adverse societal impacts such as floods and landslides. However, observational network over the region is rather sparse, and coherent data capable to assess physical properties of the atmosphere are limited, especially on diurnal time scale.

A good example of complex interaction can be found in Sumatra, where the diurnal evolution of convective development and precipitation is characterized by two modes. Convective clouds start developing before noon along the western, up-wind slopes of Barisan Mountains and they grow and move in-land, advected by the mean flow in the lower - middle troposphere, during the afternoon. However, there is also propagation in the opposite direction: an off-shore, upwind propagation of squall lines, which results is an off-shore precipitation maximum throughout the evening and night. This local variability is strongly modulated by a large-scale circulation variability. That interaction impacts precipitation over the island as well. There have been proposed several physical mechanisms that explain the off-shore progression of precipitating cloud systems on diurnal time scale, but they were primarily based on numerical experiments with high resolution models. Due to the lack of observational data that can match or at least compare with such model data, these models are rather poorly constrained.

The aim of the Barisan-Anai Meteorological Network (BAM-Net) is to fill that observational gap by providing a consistent, long-term near surface meteorological data (pressure, temperature, humidity, horizontal winds, rainfall, cloud cover) with 1Hz temporal resolution. This dataset will be able to monitor diurnal cycles of all these properties, and their variability associated with assorted subseasonal and seasonal modes, in the a representative region on the west coast of Sumatra. Data will be collected over at least 18 months along the Anai Valley, between the coast of Indian Ocean and top of Barisan mountains, north of Padang. The BAM-Net observations are being collected since March 2024.

This submission focuses on introduction of BAM-Net and access to the data. We will also present collected data and analysis of diurnal variability of near surface atmospheric properties. We will also discuss our research plans and future improvements as well as potential expansion of the network.