LIDAR (Light Detection And Ranging) is a remote sensing technology that can distinguish DSS particles which cannot be seen with the naked eye from other atmospheric pollutant particles (e.g. air pollutants), and that can monitor such particles on a real-time basis. In this page, the distribution of DSS near the ground is estimated and represented as point of color based on the monitoring results (provisional data) of LIDAR.
- Fukue Is.
- Ulaan baatar
- Sayn Shand
- Jeju Is.
|Observation Point||Ulaan baatar|
|Observation Point||Sayn Shand|
|Observation Point||Jeju Is.|
|Observation Point||Fukue Is.|
- Observation Point
- DSS Distribution
(latest 12 hours)
(latest 7 days)
Latest DSS Distribution
LIDAR is a remote sensing equipment that uses laser beam to measure in real-time DSS passing in the sky.
Many things could be identified by analyzing the laser beams scattered back from suspended matter that is originally transmitted from the ground.
The real-time monitoring data is automatically sent from the observation points, and is updated approximately around 30 minutes every hour.
(For example, the data for the time period between 09:00 to 10:00 is updated at 10:30.)
Although atmospheric pollutant particles generated from such as exhaust gas are generally spherical, DSS particles are not (see the photograph on the right).
Since LIDAR can distinguish this difference in shape, it is possible to distinguish DSS from other atmospheric particles that cannot be seen with the naked eye.
Electron microscope photograph
of DSS particles
（from the DSS Pamphlet）
Polarized laser beam (where the phases of light waves are all in the same direction) is used in LIDAR.
The state of polarized laser beam does not change and is scattered back to the ground when the laser hits spherical matter.
However, when a laser beam hits non-spherical matter, scattered light is reflected in a disordered angle, and through such extent of scattered light, the shape of the suspended matter can be determined.
It is possible to estimate the amount (distribution) of suspended matter based on the amount of laser beams that hit fine particles and are scattered back.
The point color displayed on the screen represent the average distribution of DSS near the ground (up to 1 km above ground).
The figures listed on this page are DSS distributions calculated based on data (changes in the amount of light) obtained from LIDAR. The DSS distributions [mg/m3] used on this page represent observed values (amount of light), which are calculated as the (estimated) amount of DSS based on the characteristics of the corresponding region.
■ Figure showing the principle of estimating the amount (distribution)
of suspended matter based on the amount of laser beams
Based on the disorder of laser beams that hit fine particles and are scattered back, it is possible to determine DSS vertical distribution (= area above the air and to the extent DSS is occurring in real-time).
When "Vertical Distribution" on graph area is clicked、distribution of the DSS, 6km above ground by altitude, will be displayed by color.
For example, if only the top part of a graph is red, it means the DSS is not occurring close to the ground, but rather, it is passing through the air close to 6 km above ground.
■ Principle of comprehending the altitude of suspended matter
When you click on Point Name, window appears and the hourly changes in the DSS distribution at the point are displayed. In addition, by switching the selection button on graph area, it is also possible to display daily or time changes.
This point is highlighting when the provisional data for suspended particulate matter (SPM) distribution (SPM monitoring data from the ambient air pollution monitoring station closest to the LIDAR location) exceeds the environmental standard (hourly figure) of 0.2 mg/m3, and when the DSS distribution near the ground is determined as being high (exceeding 0.3 mg/m3) by LIDAR as well.
*This display function is available only for observation points in Japan.
SPM refers to fine particulate matter (with a particle diameter of less than 10 μm) suspended in the atmosphere, and includes, in addition to exhaust gas from automobiles and soot from factories, fine DSS particles. In spring, the distribution of SPM may become high temporarily due to the impact of DSS. As a result, when this point is highlighting (= when high distribution is observed both by SPM and LIDAR), DSS is likely to be occurring near the ground.
The CFORS image displayed on the bottom left of the screen is a forecast for the distribution of DSS in East Asia based on a simulation model using LIDAR data. This information is provided as part of joint research by the National Institute for Environmental Studies and Kyushu University. On this page, the distribution diagram for the time closest to the displayed time is shown.
■ The CFORS distribution diagram shows the average distribution of DSS up to 1 km in altitude from the ground surface.
■ For seasons other than spring, a slightly higher figure is displayed.
■ Forecast distribution diagrams up to the day after next can be viewed on the CFORS home page.
In addition to LIDAR data, SPM data and visibility data are also important DSS information.
Since DSS consists of particulate matter, monitoring results of SPM also serve as a reference for the real-time distribution of DSS blown to the ground level. However, it should also be noted that SPM monitoring data do not represent the distributions of DSS by themselves. From "Atmospheric Environmental Regional Observation System: AEROS"(Japanese text only), click the region that you want to view, and select "浮遊粒子状物質(SPM)" to view the data.
On the "Aeolian Dust Information" page of the Japan Meteorological Agency, the points at which DSS or local sand/dust haze was observed visually by observers are displayed, regardless of the distribution (distance observable in horizontal direction) of such DSS or sand/dust.
When the sky is hazy, does that mean that DSS is occurring?
Even when the sky is hazy it does not necessarily mean that DSS is occurring. The sky is sometimes hazy due to particulate matter originating from atmospheric pollution. Since LIDAR can distinguish between DSS and atmospheric pollutant particles, which is difficult to do visually, please refer to the information on this Real-time DSS Information website. The visibility near the ground may be poor sometimes due to sand and dust flying locally.
Is the DSS today heavy or light?
The point color on this map area correspond to the amount of DSS floating near the ground (up to 1 km above ground). (Note: On cloudy days, the height represents the amount of DSS up to the height of the clouds.) As a result, by comparing the real-time screens with the past DSS events, it is possible to compare whether the current DSS is heavier or lighter than the past DSS. In Japan, DSS rarely exceeds 0.3 mg/m3 when converted to concentration, but if DSS exceeding 0.3 mg/m3occurs near the ground, it may cause visible dirt on laundry and cars.
For the amount of DSS near the ground, the distribution of suspended particulate matter (SPM) also serves as a reference. On the page for SPM data, i.e. "Soramamekun" (Japanese text only) , select the region that you want to view and the display item "Suspended Particulate Matter". When there is DSS event and the SPM distribution is higher than the range displayed in yellow, it can be determined that there is a heavy DSS.
In addition, in this page, when the provisional data (hourly figure) for the SPM observation data at the ambient air pollution monitoring station closest to the LIDAR location exceeds 0.2 mg/m3 and, moreover, the DSS near the ground is heavy (exceeding 0.3 mg/m3) based on LIDAR, the point is highlighting.
Is it true that some DSS may pass through the air over Japan?
When you click on a "Vertical Distribution" on the graph area, a colored panel is displayed, and it is possible to see the area around which the DSS passed over as well as the extent of the DSS, up to 6 km above ground. When only the top part of the graph is red, the DSS is judged not to be occurring on the ground, but simply passing through the air.
Is it safe to hang my laundry out to dry tomorrow?
Since the Japan Meteorological Agency forecasts DSS for the following day, please look at the Japan Meteorological Agency's announcement on their "Aeolian Dust Information page". On the CFORS page, which is provided by the National Institute for Environmental Studies and Kyushu University as part of their joint research using LIDAR data, simulation results for up to the day after next are available for reference.
Where did the DSS over Japan today originate from?
DSS originates from source areas such as the Takla Makan Desert, Gobi Desert, and Ocher Plateau in inland China to Japan through various transport processes. It is possible to retroactively view the paths of DSS from its source area to Japan in the past by using animated DSS distribution diagrams based on model calculations on the CFORS page. Please use the CFORS page as a reference.
|Operating Body||Location||Longitude, latitude|
|Japan||Sapporo||Hokkaido University||Sapporo City,Hokkaido Prefecture
|Sendai||Tohoku University||Sendai City, Miyagi Prefecture||140.85E, 38.25N|
|Tsukuba||National Institute for Environmental Studies||Tsukuba City, Ibaraki Prefecture
(National Institute for Environmental Studies)
|Tokyo||Ministry of the Environment||Shinjuku-ku, Tokyo
|Chiba||Chiba University and National
Institute for Environmental Studies
|Chiba City, Chiba Prefecture
|Niigata||Ministry of the Environment||Niigata City, Niigata Prefecture
(Asia Center for Air Pollution Research)
|Toyama||Ministry of the Environment||Imizu City, Toyama Prefecture
(Toyama Prefectural Environmental Science Research Center)
|Osaka||Kinki University and National
Institute for Environmental Studies
|Higashiosaka City, Osaka Prefecture
|Matsue||Ministry of the Environment||Matsue City, Shimane Prefecture
(Shimane Prefectural Institute of Public Health and Environmental Science)
|Nagasaki||Ministry of the Environment||Omura City, Nagasaki Prefecture
(Nagasaki Prefectural Institute for Environmental Research and Public Health)
|Fukue Is.||Research Institute for Humanity and Nature||Goto City, Nagasaki Prefecture
(Research Institute for Humanity and Nature)
|Okinawa||National Institute for Environmental Studies||Kunigami Village, Okinawa Prefecture
(Cape Hedo Aerosol and Atmosphere Monitoring Station)
|Korea||Seoul||Seoul National University and
National Institute for Environmental Studies
(Seoul National University)
|Jeju Is.||Seoul National University/NIES||Gosan, Jeju, Korea||126.16E,33.29N|
|Mongolia||Ulaan baatar||National Agency for Meteorology,
Hydrology and Environmental
|UlaanbaatarNational Agency for
Meteorology, Hydrology and
|Sayn Shand||National Agency for Meteorology,
Hydrology and Environmental
(Sayn Shand Meteorological Station)
|Zamyn-Uud||National Agency for Meteorology,
Hydrology and Environmental
(Zamyn-Uud Meteorological Station)
|China||Beijing||The Sino-Japan Friendship Centre for Environmental Protection and National Institude for Environmental Studies||Beijing
（The Sino-Japan Friendship Centre for Environmental Protection）
Menu for Related MOEJ DSS
- DSS Top Page (Japanese text only)
- What is DSS? (Japanese text only)
- Past records of DSS (Japanese text only)
- Reports of Special Committee on DSS Issues
- Measures against DSS by MOEJ (Japanese text only)
- Other DSS Links (Japanese text only)
- DSS Pamphlet
- DSS Information Website by MOEJ and JMA (Japanese text only)