Newsletter Issue 48 (October 2024)

香港氣象學會參觀交流團 – 為免向隅，報名從速

香港氣象學會擬於2024年12月14日(星期六)籌辦交流團參觀佛山市氣象局和 中國氣象局龍卷風重點開放實驗室。誠邀會員參加，活動詳情及報名方法，請參照連結 https://forms.gle/XeSBPeWThWgYwUqZ9 。為免向隅，報名從速﹗

The weather of September 2024 – A wet and unseasonably hot September

Mainly attributing to weaker than normal northeast monsoon over southern China, September 2024 was much hotter than usual in Hong Kong. The mean temperature, mean maximum temperature and mean minimum temperature were respectively the third, one of the fourth and one of the seventh highest for September on record. Waterspout was also reported over the sea off Hung Hom, the first occurrence in Victoria Harbour according to reports received by the Observatory since 1959.

Second-warmest September globally and in Europe

According to ERA5, which provides hourly temperature data from 1940, September 2024 was 1.54°C above the pre-industrial level. This was the 14th month since July 2023 in which the global-average surface air temperature exceeded 1.5°C above pre-industrial levels. “September 2024 was the second warmest both globally and for Europe… The risk of extreme rainfall will continue to increase with rising temperatures; the sooner we reach NetZero emissions, the sooner we can mitigate this risk.” said Samantha Burgess, Deputy Director of the C3S.

2024 Antarctic sea ice winter maximum second lowest on record

The sea ice in the Southern Ocean around Antarctica probably reached its winter maximum extent on September 19, 2024, according to the National Snow and Ice Data Center. The area around Antarctica where the ocean was at least 15 percent ice covered reached 17.16 million square kilometers before starting its annual spring melt. The 2024 ice extent was second smallest of the satellite record, only slightly above the extreme record low set in 2023.

UN General Assembly highlights WMO’s leadership on early warnings and climate action

The opening days of the 79th session of the United Nations General Assembly have highlighted the need for global action to address climate change and the growing impact of extreme weather events. As a core part of this year’s discussions, the World Meteorological Organization took center stage with the Early Warnings for All (EW4All) Initiative, which aims to protect every person on Earth from hazardous weather through life-saving early warning systems by 2027.

Scientists have more evidence to explain why billions of crabs vanished around Alaska

According to the State of Global Water Resources Report coordinated by the WMO, which signaled critical changes in water availability in an era of growing demand:
– 2023 was driest year for global rivers in 33 years
– Glaciers suffer largest mass loss in 50 years
– Climate change makes hydrological cycle becomes more erratic
– Early Warnings for All must tackle water-related hazards

NOAA shares imagery from world’s first operational space-based coronagraph

NOAA shared the first images from the Compact Coronagraph (CCOR-1), a powerful solar telescope onboard the new GOES-19 satellite. CCOR-1, the world’s first operational, space-based coronagraph, began observing the sun’s corona, the faint outermost layer of the solar atmosphere, on September 19, 2024. CCOR-1 monitors the corona to forecast coronal mass ejections, which are large expulsions of plasma and magnetic fields from the sun that can produce space weather impacts on Earth.

The planet’s largest lake is shrinking fast. Experts fear it may never recover

While climate change is raising global sea levels, it’s a different story for landlocked seas and lakes like the Caspian. They rely on a delicate balance between water flowing in from rivers and rainfall and leaving through evaporation. Damming, over-extraction, pollution and, increasingly, the human-caused climate crisis are driving its decline — with some experts fearing the Caspian Sea is being pushed to the point of no return.

Hurricane Helene: Breaking records in hurricane data collection

As Hurricane Helene developed in the Gulf of Mexico, NOAA researchers gathered critical data from the sea and sky to better understand tropical cyclones and support the National Hurricane Center forecasters. This real time data gives meteorologists a clearer picture of the storm environment and structure, reducing forecast uncertainty. In addition to operational radar and dropsonde data, scientists are experimenting with emerging technologies like the Black Swift S0 drone, which gathers atmospheric data from the storm’s lowest levels, which were not previously accessible.

Is the UN warning of 3.1C global warming a surprise?

The headlines are pretty grim – without action the world could warm by a massive 3.1C this century, the UN says in the UN Emissions Gap report. The report indicates that if only “current policies” are implemented the world could warm by up to 3.1C. This would be “catastrophic” for the world, leading to dramatic increases in extreme weather events including heatwaves and floods. But how likely is that? As is often the case with climate change and the science behind it – the answer is complicated.

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