The ion density probed by IAP (Instrument d’Analyse du Plasma) on board the DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) satellite is used to find whether the science payload of Advanced Ionospheric Probe (AIP) on board FORMOSAT-5 can be employed to observe space weather of ionospheric plasma irregularities. The low-latitude irregularities within ±15° dip latitudes of the DEMETER/IAP ion density are nighttime phenomena, and become prominent in the South America-Central Africa sector almost all year round, especially during May to August. The high-latitude irregularities of the DEMETER/IAP ion density appear around ±65° dip latitude worldwide in both daytime and nighttime, and become very intense in the winter and the equinox month/hemisphere. DEMETER/IAP results show that FORMOSAT-5/AIP can be used to monitor space weather of ionospheric daytime/nighttime plasma irregularities in not only the low- but also high-latitude ionosphere.