Review of Regional Haze Situation for May 2022 |

Review of Regional Haze Situation for May 2022

1.1 Inter-monsoon conditions started to give way to Southwest Monsoon conditions through May 2022 as the monsoon rainband continued to move northwards over the northern ASEAN region. The prevailing winds over the ASEAN region blew generally from the southeast or southwest, except for regions close to the Equator where winds were light and variable in direction (Figure 1).

1.2 Rainy weather was observed over most of the ASEAN region in May 2022 although drier conditions prevailed over the Lesser Sunda Islands and the northernmost parts of the Mekong sub-region. Heavy rainfall was observed in parts of southern Philippines, as well as the southern parts of both Myanmar and Thailand (Figure 1).

Figure 1: Average Daily Rainfall and Mean Winds for May 2022. (Source: JAXA GsMaP and GFS, respectively)

1.3 For May 2022, the total number of hotspots were lower or comparable to previous years for the same period (Figures 2 and 3), except in Sumatra and Kalimantan where a slightly higher number of hotspots were detected in May 2022 compared to previous years.

Figure 2: Hotspot counts for the southern ASEAN region for the month of May (2018 – 2022). [Note: The hotspot counts from 2019 onwards are based on the NOAA-20 satellite, while those from 2018 are based on the Suomi-NPP satellite.]

Figure 3: Hotspot counts for the northern ASEAN region for the month of May (2018 – 2022). [Note: The hotspot counts from 2019 onwards are based on the NOAA-20 satellite, while those from 2018 are based on the Suomi-NPP satellite.]

1.4 Isolated to scattered hotspots (Figures 4 and 5) and moderate smoke haze (Figure 6) were observed in the first week of May 2022 over northern parts of the Mekong sub-region. However, the onset of wetter conditions over the northern ASEAN region in subsequent weeks helped to suppress hotspot and smoke haze activities here. As wet conditions became established, the Alert Level over the Mekong sub-region was downgraded to Alert Level 1 on 10 May 2022, and the End of Dry Season (Alert Level 0) was declared on 19 May 2022.

1.5 The hotspot and smoke haze situation in the southern ASEAN region remained subdued as rainy conditions continued to prevail. Isolated hotspots were detected (Figures 4 and 5) and localised smoke plumes were observed to emanate from some of these hotspots in Borneo and the central Sumatra on some days.

Figure 4: Distribution of hotspots detected in May 2022 based on NOAA-20 satellite surveillance.

Figure 5: Maximum fire intensity in May 2022 based on NOAA-20 satellite surveillance.

Figure 6: Number of days with moderate to dense smoke haze observed in May 2022 based on satellite imagery, ground observations, and air quality reports.