Ms. Pham Thi Thanh Nga, Deputy Director of Meteorology, Hydrology and Climate Change (Ministry of Natural Resources and Environment) answered VnExpress about the impact of El Nino on three regions.
– At the beginning of June, the international meteorological agency announced that El Nino began to appear, but why from April to May, Vietnam has experienced hot days with many records set?
– First we have to understand about El Nino. El Nino and La Lina are two opposite phases of the ENSO phenomenon, indicating the anomalous warming and cooling of sea surface temperatures in the eastern equatorial and central Pacific Ocean, with a period of about 8-12 months, sometimes 3-4 years. ENSO is one of the most important climate phenomena on Earth due to its ability to alter the atmospheric circulation on a large scale, which in turn affects global temperature and precipitation. But the impact will vary from region to region in terms of size and duration.
Historical data shows that normally in El Nino years, Vietnam has higher than average temperatures for many years, rainfall is insufficient, causing heat, drought and saltwater intrusion. The most typical are two severe droughts and saltwater intrusion that occurred during the strong El Nino period, the dry seasons 2015-2016 and 2019-2020. El Nino will have a very different impact between climate regions and according to the active period, such as before, forming, starting, developing and weakening.
Last April and May was the period before the formation of El Nino, a rapid phase transition from cold to hot, there was a strong disturbance of ocean surface temperature, leading to forced changes in the atmosphere. This sign shows that the temperature of the ocean surface in April and May this year is higher than the average of many years.
However, the unusual heat in April-May is not the impact of El Nino, but due to the global warming effect, leading to many changes in atmospheric circulation; The hot western low pressure was active early and intensely combined with the phono effect (due to the topographical conditions of Vietnam). The average global temperature has been increasing every year since 2015 until now, regardless of El Nino or La Nina phase.
– El Nino appears at the peak of summer in the North and Central, but why is it cool for more than 20 days in the North?
– As mentioned above, the impact of El Nino on temperature is very variable between active periods and is usually most pronounced in the growing and waning phase. In the first 20 days of June, some northern areas have sunny days, evenings and thunderstorms, so we have a more pleasant feeling of coolness. The meteorological agency also did not record a temperature record.
However, the fact that the temperature monitoring data in the first 20 days of June is common in the North and Central Vietnam is higher than the average value of many years in the same period by 0.5-1 degrees Celsius, in some places by 1.5- 2 degrees Celsius. The average daily temperature in the South Central and Southern regions is also higher than the average value of many years by about 0.5 degrees Celsius.
– How will El Nino affect the three regions of Vietnam?
– It is forecast that most regions in the country will have a higher average temperature than normal; the heat can be more and more intense; the possibility of multiple records appearing. When El Nino appears, heat increases in the summer (shown in the maximum temperature or number of hot days), reducing the chance of severe cold spells and prolonged cold spells in the winter.
Rainfall will be short on most of the country with a prevalence of 25-50%, even historically Buon Ma Thuot recorded a shortage of 69%. Since then, there is a high risk of local or large-scale drought in some regions such as North Central, South Central, Central Highlands and South.
The activity of storms and tropical depressions in the East Sea and affecting Vietnam may not be much, but concentrated in the middle of the season, the nature is more anomalous in both intensity and trajectory.
El Nino years may also appear unusually with heavy rain and harmful cold in some areas, such as the 2015-2016 El Nino period, which occurred with a record heavy rain in Quang Ninh on July 25-August 4. In the winter of 2015-2016, severe cold, widespread cold in the North, the lowest temperature in Sa Pa was -4.2, Mau Son -4.4, Pha Din -4.3 degrees Celsius. Snow and ice appeared present in places where there has never been snow in history, such as Ba Vi (Hanoi) and Ky Son (Nghe An). Therefore, irregularities or irregularities are the same risks caused by the impact of El Nino.
Da River is bottomless, June 2023. Photo: Ngoc Thanh
– When and where is the forecast of the most negative impact of El Nino in Vietnam?
– El Nino combined with global warming trends due to climate change makes Asia likely to experience powerful heat waves, with record-breaking temperatures in South Asia, southern China to Southeast Asia . However, compared with other regions such as India and Australia, the average temperature increase of Vietnam is lower, mainly in the months of June-July and the northern region of Vietnam.
In Vietnam, the most negative impact of El Nino is during the period of development, degradation and disintegration, especially the heat wave, reduced rain in some areas, leading to water shortage, drought, and saltwater intrusion. may occur with high frequency. For example, drought in the spring and summer in the North Central and South Central regions and drought in the winter and spring in the South and Central Highlands.
– In Vietnam, how long will El Nino last?
– According to current forecast results of major centers in the world, El Nino can last until early spring 2024 with a probability of about 80%. Analysis by the National Oceanic and Atmospheric Administration (USA), the maximum sea surface temperature in the Nino 3.4 area may start from October 2023 to February 2024, the time El Nino reached the strongest intensity.
The impact of El Nino on Vietnam will increase in the last months of 2023 and early 2024. The dry season in the Central Highlands and the South is likely to be more severe, drought and saltwater intrusion may occur on a large scale. into this period.
According to VnExpress.net
