The cold pool outflow has been previously shown to be generated by decaying Mesoscale Convective Complexes (MCCs) in the Maritime Continent. The cold pool also has a main role in the development processes of oceanic convective systems inducing heavy rainfall. This study investigated a cold pool event (January 1-2, 2021) related to a heavy rainfall system over the coastal region of Lampung, Southern Sumatra, within a high-resolution model simulation using a regional numerical weather prediction of the Weather Research and Forecasting (WRF) with convection permitting of 1 km spatial resolution, which was validated by satellite and radar data observations. It is important to note that the intensity, duration, timing, and structure of heavy rainfall simulated were in good agreement with satellite-observed rainfall. The results also showed that a cold pool (CP) plays an important role in inducing Mesoscale Convective Complex (MCC) and was responsible for the development of an offshore propagation of land-based convective systems due to the late afternoon rainfall over inland. This study also suggests that the propagation speed of the CP 8.8 m·s−1 occurring over the seaside of the coastal region, the so-called CP-coastal, is a plausible mechanism for the speed of the offshore-propagating convection, which is dependent on both the background prevailing wind and outflow. These conditions help to maintain the near-surface low temperatures and inhibit cold pool dissipation, which has implications for the development of consecutive convection.

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This study examines the use of principal component analysis (PCA) to classify the RDSD data at Kototabang, Indonesia. In addition to PCA with 6 attributes (hereinafter called PCA6) that had been developed by a previous researcher, this study also examines PCA with 7 attributes (PCA7) by adding radar reflectivity factor. The PCA is applied to the RDSD that had been classified by a wind profiler into Stratiform (S), deep convective (DC), shallow convective (SHC) and mixed stratiform/convective (MSC). The number of unclassified data is much smaller than that reported by previous study in which it is about 33-47% with PCA6 and 29-44% with PCA7. While the PCA classifies the same group for different rain type from wind profiler, especially for Group I (moderate Do and large N W ) and II (small Do and N W ), some differences are observed. Each rain type classified by wind profiler has different dominant group in which Group II is dominant for S, Group I and V (large Do and low N w ) are dominant for DC, Group I, IV (small Do and large N w ) and VI (small Do and very large N w ) are dominant for SHC and Group I is also dominant for MSC type.

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Distribusi spasial dan temporal petir di Sumatera Barat telah diteliti dengan menggunakan data satelit Tropical Rainfall Measuring Mission-Lightning Imaging Sensor (TRMM-LIS) selama 16 tahun pengamatan (1998-2013). Hubungan antara petir dan curah hujan diteliti dengan memanfaatkan data TRMM 3B43. Hasil penelitian menunjukkan bahwa petir di Sumatera Barat banyak terjadi di darat dengan densitas tertinggi terjadi pada bulan Desember, Januari dan Februari (DJF). Petir di darat banyak terjadi pada sore hari mulai jam 17.00 LST hingga tengah malam dan kabupaten Dharmasraya merupakan daerah yang memiliki densitas kilatan petir tertinggi terutama selama periode DJF. Siklus diurnal petir konsisten dengan siklus migrasi awan dari laut ke daratan Sumatera yang ditemukan oleh peneliti sebelumnya. Hubungan curah hujan dan petir di Sumatera Barat bervariasi antara satu kabupaten dengan kabupaten lainnya. Berdasarkan nilai regresi linier antara petir dan curah hujan terlihat bahwa daerah yang memiliki korelasi yang cukup kuat antara densitas petir dan curah hujannya adalah Kabupaten Solok,  Solok Selatan, Padang Pariaman, dan 50 Kota sedangkan daerah yang memiliki korelasi yang rendah adalah Kepulauan Mentawai, Pesisir Selatan, dan Agam. Dengan demikian, di beberapa kabupaten petir dapat menjadi indikator untuk penentu curah hujan tetapi tidak untuk beberapa kabupaten yang lain.Kata kunci: distribusi petir, Sumatera Barat, TRMM