Review of Regional Haze Situation for February 2023 |

Review of Regional Haze Situation for February 2023

1.1 The ASEAN region continued to experience Northeast Monsoon conditions in February 2023. Over areas north of the equator, the prevailing winds blew mainly from the northeast even though the winds were mostly light and variable in direction over the Mekong sub-region. For areas south of the equator, the prevailing winds blew mostly from the west or northwest (Figure 1).

1.2 Dry conditions persisted over the Mekong sub-region throughout the review period of February 2023, except for isolated shower activities in the southern parts of the sub-region on some days. Elsewhere in the ASEAN region, rainy weather was observed in many areas. However, parts of Peninsular Malaysia and the northern Philippines experienced brief periods of drier weather. (Figure 1).

Figure 1: Average Daily Rainfall and Mean Winds for February 2023. (Source: JAXA GsMaP and GFS, respectively)

1.3 Prolonged dry conditions over the Mekong sub-region led to an increase in overall hotspot activity in February 2023 and the hotspot counts in the Mekong sub-region were higher or comparable to previous years (Figure 2). In particular, the highest hotspot activity was detected in Myanmar, and the hotspot counts for both Myanmar and Lao PDR were the highest in 5 years. For the southern ASEAN region, hotspot activity remained generally subdued and the hotspot counts were generally lower than in previous years (Figure 3).

Figure 2: Hotspot counts for the northern ASEAN region for the month of February (2019 – 2023) based on NOAA-20 satellite surveillance.

Figure 3: Hotspot counts for the southern ASEAN region for the month of February (2019 – 2023) based on NOAA-20 satellite surveillance.

1.4 Hotspot activity was widespread and persistent over the Mekong sub-region during the review period of February 2023. On many days, clusters of hotspots were detected in parts of Lao PDR, northern and eastern Cambodia, northern and central Myanmar, and northern Thailand. Isolated hotspots were also detected in northern Viet Nam. Over the southern ASEAN region, few hotspot activities were detected but most of them was short-lived (Figure 4).

Figure 4: Distribution of hotspots detected in February 2023 based on NOAA-20 satellite surveillance.

1.5 The overall fire intensity in the Mekong sub-region had increased in February 2023, particularly over the fire-prone areas in Lao PDR, northern and central Myanmar, northern and eastern Cambodia, and northern Thailand (Figure 5). As a result, moderate to dense smoke haze was observed in the vicinity of the hotspot clusters in Myanmar, Thailand, and Cambodia (Figure 6, 7, 8 and 9) on many days. Localised smoke plumes and occasional hazy conditions were also observed in northern Viet Nam on some days.

Figure 5: Maximum fire intensity in February 2023 based on NOAA-20 satellite surveillance.

Figure 6: Number of days with moderate to dense smoke haze observed in February 2023 based on satellite imagery, ground observations, and air quality reports.

Figure 7: Moderate to dense smoke haze observed over northern and central Myanmar on 24 February 2023, based on NOAA-20 satellite surveillance.

Figure 8: Moderate to dense smoke haze emanated from the hotspot clusters detected in northern and central Thailand on 24 February 2023, based on NOAA-20 satellite observation.

Figure 9: Moderate smoke haze emanated from the hotspot clusters detected in northern and eastern Cambodia on 20 February 2023, based on NOAA-20 satellite observation.