Centennial History of Upper Air Observation in Hong Kong
1921 – 1930's
| 1921 | - | Started upper air observation |
The Observatory's upper air meteorological observation began in 1921. At the time, pilot balloons were launched at the Observatory Headquarters in Tsim Sha Tsui, and a theodolite was used to track the balloons for calculating the upper air wind direction and speed.
Staff of the Observatory launching a pilot balloon at the Tsim Sha Tsui Headquarters in the 1930s. The staff on the left was holding a pilot balloon.
Staff operating the theodolite to record the balloon's azimuth and elevation angle, for calculating the upper air wind direction and speed.
(Photographs provided by family of Mr. G.S.P. Heywood, former Director of the Observatory)
| 1924 | - | The Observatory cooperated with the Royal Air Force for the first time to measure upper air temperatures by aircraft |
| 1938 | - | The Far East Flying Training School began to provide the Observatory with upper air temperature and humidity measurement data |
1940's – 60's
| 1949 | - | Use of radiosonde in upper air sounding |
In 1949, the first upper air sounding system using radiosondes was installed at the Observatory Headquarters to carry out routine upper air weather observations at 8 a.m. every day. The Observatory staff manually inflated a balloon, with a radiosonde dangling from it, with hydrogen and released it. As the balloon rose in the air, measurements of upper air temperature, humidity and air pressure taken by sensors in the radiosonde were transmitted to the ground station at the Observatory Headquarters by radio waves. As for the measurement of upper level winds, a theodolite on the rooftop of the Observatory Headquarters was used to track the balloon for calculating the wind direction and speed at different heights above ground.
Observatory colleagues conducting an upper air meteorological observation experiment on the rooftop of the Observatory Headquarters by operating a theodolite to track the balloon. (Photograph provided by the family of Mr. L. Starbuck, former Deputy Director of the Observatory)
Observatory colleagues were preparing to launch an upper air meteorological balloon in front of the 1883 Building at the Observatory Headquarters. The colleague on the far left was holding the radiosonde and the one in the middle was holding the balloon. Due to the relatively large size and heavy weight of the instrument at that time, a dedicated personnel was required to operate the radiosonde. (Photograph provided by Mr. Shun Chi-ming, former Director of the Observatory)
| 1951 | - | Commencement of King's Park Radiosonde Station |
The Observatory Headquarters at Tsim Sha Tsui became no longer the best place for upper air meteorological observations due to the gradual increase of surrounding buildings. A more suitable place for releasing meteorological balloon was found on a small hill at King's Park, where a meteorological station was then established in 1951. Since 1 June 1951, routine measurements of upper air temperature, humidity, air pressure and winds were carried out at 8 a.m. daily at King's Park. The station was known as the King's Park Radiosonde Station when it was first set up. With the increase of surface meteorological measurements at the station, it was renamed the King's Park Meteorological Station (KPMS) in the 1960s.
On 9 November 1951, guests were watching the launch of sounding balloon in the inauguration ceremony of the meteorological station. (Photograph provided by the family of Mr. L. Starbuck, former Deputy Director of the Observatory)
The then Governor, Sir Alexander Grantham (right), officiated at the opening ceremony of the meteorological station on 9 November 1951, listened attentively to Mr. Heywood (left), then Director of the Observatory, explaining how a new instrument worked. (Photograph provided by Mr. Heywood's family)
| 1951 | - | Use of radar in tracking balloons |
The technology of measuring upper level winds took a step forward in 1951. In addition to the radiosonde, a radar reflector was also attached to the upper air meteorological balloon. Colleagues employed a ground-based army radar to track the movement of the radar reflector and determined the reflector's range, azimuth and elevation, from which the upper level wind direction and speed could be computed.
The army radar in the photo could track the position of the radar reflector attached to an upper air meteorological balloon so as to measure the winds aloft. (Photograph provided by the family of Mr. G.S.P. Heywood, former Director of the Observatory)
| 1954 | - | Increased the number of daily upper air observations |
Starting from 16 October 1954, in addition to the routine measurements of upper level temperature, humidity, air pressure and winds at 8 a.m. every day, additional observations were also made at 5 a.m., 5 p.m. and 11 p.m. for only wind direction and speed. At the request of the World Meteorological Organization (WMO), starting from 1 April 1957, these three observations were advanced to 2 a.m., 2 p.m., and 8 p.m.
| 1969 | - | Starting from 1 January, the 8 p.m. observation also covered temperature, humidity and air pressure measurements |
Early days of upper air meteorological observations at King's Park
In the early days of upper air meteorological observations at King's Park, a radar (mounted on the rooftop of the building) was used to track the position of the meteorological balloon.
In the early days, it took three Observatory colleagues' efforts to carry out the work of upper air meteorological observation. They were responsible for operating the radiosonde equipped with a windmill, releasing the balloon, and operating the radar to track the balloon respectively. (Please watch the silent video clip)
1970's - 90's
| 1978 to 79 | - | Launching of sounding balloon on ships |
In 1978-79, the Observatory participated in the WMO's Global Weather Experiment to launch sounding balloons on board a naval vessel and a merchant ship to collect upper air meteorological data over the South China Sea.
Launching of sounding balloon by the Observatory on a ship in the South China Sea in the 1970s
| 1981 | - | Use of MicroCORA sounding system |
In 1981, a MicroCORA sounding system was put into operation at the KPMS. The system employed the frequency at 403 MHz for transmission of temperature, humidity and air pressure signals to the ground station. The system automatically converted the radio wave signals into usable data without the need of manual calculation. The system also featured a technological breakthrough in upper level wind measurements. It used the phase difference of the very low frequency signals in the range of 10-13 kHz from a global-range navigational network, OMEGA, for automatic tracking of radiosondes and computation of winds. The use of radar to track radiosondes became no longer required.
| 1992 | - | Became a member of the Global Climate Observing System (GCOS) |
In 1992, the GCOS, funded by the WMO, United Nations Educational, Scientific and Cultural Organization (UNESCO) and others, was established. The KPMS became a member of the GCOS Upper-Air Network (GUAN) and contributed to the monitoring of climate change. Currently, there are more than 170 GUAN upper air meteorological stations around the world, launching meteorological balloons at the same time to collect upper air weather data at 8 a.m. and 8 p.m. Hong Kong time daily.
| 1993 | - | Sounding operation went digital |
| - | Started measuring upper air ozone and radioactivity |
In 1993, the Observatory introduced the DigiCORA sounding system, which could support measurements of upper air ozone content as well as gamma and beta radioactivity vertical profiles using specially designed radiosondes. Since then, the Observatory has been carrying out ozone sounding once a week and regular radioactivity soundings under different weather conditions each year.
The sensor used during the first radioactivity sounding at the KPMS on 26 February 1993. The probes on the left and right were the Geiger Müller tube that measured beta and gamma radiation respectively.
The sensor used in the first ozone sounding at the KPMS on 4 March 1993. The electrochemical reactions between ozone and the electrolytes of the cell (bottom right) gave rise to a small electric current proportional to the ozone abundance of the sampled air.
Staff of the Observatory operating the DigiCORA system
| 1997 | - | Use of global positioning system (GPS) |
The radiosonde started to employ the Global Positioning System (GPS) wind-finding technology in 1997, marking a big step forward for upper air wind observations. During the observations, both radiosonde and ground station were equipped with special antennae for receiving satellite-based GPS signals. These signals enabled the computation of winds aloft. In 1999, the Observatory also employed the “LORAN-C” radio navigation system, as an alternative to GPS technology, for location fixing and measurement of upper level winds.
Evolution of radiosondes
In the 1950s and 60s, the radiosonde used at King's Park was quite large and heavy. The instrument, together with the battery, weighed more than one kilogram. With the advancement of technology, components were getting smaller and smaller. A new type of radiosonde was brought into use at the meteorological station in 1969 with the weight of the radiosonde greatly reduced to 280 grams. The latest model of radiosonde, adopted since 2016, weighs only 80 grams.
2000 to present
| 2000 | - | Became a monitoring station of the Global Atmosphere Watch Programme |
Since 2000, the KPMS has become an ozone monitoring station of the WMO Global Atmosphere Watch Programme. Weekly observations are sent to the World Ozone and Ultraviolet Radiation Data Centre for archival and research purpose by meteorological agencies and scholars around the world.
The KPMS is an ozone monitoring station of the WMO Global Atmosphere Watch Programme.
| 2004 | - | Commencement of the Automatic Upper Air Sounding System |
In 2004, the Observatory installed the Automatic Upper Air Sounding System (AUSS) at the KPMS, which was the first of its kind in Southeast Asia at that time. The system automatically inflates and releases the balloon. Apart from lower operation costs and higher work efficiency, it also enhanced personnel safety. Starting from late 2008, helium has been used in place of hydrogen for inflating balloons. This further improved staff safety.
The fully Automatic Upper Air Sounding System at the KPMS commissioned in 2004, the first of its kind in Southeast Asia at that time.
| 2014 | - | Use of mobile upper air sounding system |
In 2014, the Observatory acquired a portable upper air sounding system which could enable the launch of balloons at different places in Hong Kong when needed. The system enhanced the mobility and applicability of upper air sounding operation for obtaining the required meteorological data.
Staff of the Observatory operating the mobile upper air sounding system to launch a balloon
| 2015 | - | Exploratory upper air sounding over the South China Sea |
In June 2015, staff of the Observatory used the mobile sounding system to conduct an upper air sounding experiment at sea, on board a container ship travelling from Hong Kong to Singapore.
Sounding balloon launching locations on the voyage
Adjusting the antenna of the mobile sounding system
Inflating the balloon with helium gas on board
| 2018 | - | ISO accreditation of upper air sounding operation |
The upper air sounding operation at the KPMS successfully obtained the ISO 9001:2015 certification by the International Organization for Standardization in March 2018, further affirming the professional work of colleagues. In recent years, the Observatory successfully passed the re-certification audit of the KPMS conducted by the certification body, reaffirming the high quality measurement service provided by the Observatory.
The ISO 9001:2015 certificate awarded to the KPMS and the Radiation Laboratory of the Observatory
| 2019 | - | WMO certificate to honour HKO for its long-term contribution |
In November 2019, King's Park upper air station was awarded the certificate by the WMO in recognition of its long-term contribution to supporting the Global Climate Observing System (GCOS) Upper Air Network (GUAN).
Former Director of the Observatory, Mr. Shun Chi-ming (right) receiving a certificate from Mr. Tim Oakley (left), Network Manager of the Global Climate Observing System (GCOS) in November 2019, which recognised the Observatory's upper air meteorological station for its long-term contributions to the GCOS Upper-Air Network (GUAN).
| 2020 | - | Launch of cryogenic frostpoint hygrometer |
In 2020, King's Park upper air station became a candidate site of GCOS Reference Upper Air Network (GRUAN) of the WMO, for launching cryogenic frost-point hygrometer monthly as required to provide long-term and high-quality upper-air atmospheric water vapor content data to the meteorological community.
Staff of the Observatory launching a balloon with cryogenic frostpoint hygrometer
| 2021 | - | Recognised by the WMO as a centennial upper air observing station |
In 2021, the upper air observing station in Hong Kong became the world's first centennial upper air observing station recognised by the WMO.
The long-term observing station accreditation certificate awarded by the WMO to the Hong Kong Upper Air Observing Station.