Weather forecast models have long struggled to integrate satellite observations of infrared radiation in cloudy regions of the sky. But in recent years, some satellite data providers have developed new techniques to integrate such data. A group of researchers from China, Japan, the US and the UK have performed a survey of best practice for the observation and use of this data, demonstrating significant improvement in the forecasting of high-impact weather events such as hurricanes and typhoons.

The review concluded that a method using what are called cloud cleared radiances has proved to be the effective and efficient method for use of infrared data assimilation in partially cloudy skies. This involves essentially cutting out the cloud effect in infrared 'sounder' measurements to obtain a clear-sky infrared radiation equivalent.

Sounder instruments aboard satellites 'sound the depths' of the atmosphere to take measurements that represent a 3D structure of atmospheric moisture and temperature (as opposed to satellite 'imager' instruments that produce 2D images or maps, often of the temperature of the sea, or land surface, or a thick layer of atmosphere).

Over the last decade or so, some satellite users have begun to perform data assimilation from both clear and cloudy skies, so-called all-sky assessments. But even here, this has depended mainly on the measurement of microwave but not infrared radiation. Infrared radiation measurements for weather forecasting are mostly limited to clear skies and to above-cloud situations.

This is because atop the existing problems with cloudy regions, satellite measurements of infrared radiation are strongly affected by the very layout of clouds. Complex multi-layer and overlapping clouds are difficult to assess.

Nevertheless, progress in use of the infrared in cloudy skies is critical to better represent thermodynamic and cloud microphysical information from satellites in order to improve weather forecasts.0

"Thankfully, in recent years, a great deal of experimentation on all-sky infrared data assimilation has taken place," said Wei Han, of the National Meteorological Center of the China Meteorological Administration and one of the researchers involved with the survey, "and we wanted to assess what the best practice is."

So the researchers reviewed development of satellite infrared data assimilation by various practitioners and the solutions they have deployed to better use such data in forecasts.

They found that use of these cloud-cleared radiances in data assimilation improves the forecasting of high-impact weather events such as tropical cyclones (known as hurricanes or typhoons, depending on the region of the world), and is now being applied in numerical models to improve daily forecasts.

The study also found in terms of technique that placing a high-spatial-resolution imager and a hyperspectral infrared sounder on the same platform was crucial for enhancing the effectiveness of infrared data assimilation under cloudy skies.

Research Report: "Satellite All-sky Infrared Radiance Assimilation: Recent Progress and Future Perspectives"

Related Links
Institute of Atmospheric Physics, Chinese Academy of Sciences
Bringing Order To A World Of Disasters
When the Earth Quakes
A world of storm and tempest

Thanks for being here; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor $5 Billed Once credit card or paypal		SpaceDaily Monthly Supporter $5 Billed Monthly paypal only

Sicily braces for second cyclone this week
Rome (AFP) Oct 28, 2021
Sicily braced for the arrival of a cyclone Thursday, the second this week after a deadly storm hammered the southern Italian island, killing three people. The Mediterranean cyclone known as a "medicane" was set to reach Sicily's eastern coast and the tip of mainland Calabria between Thursday evening and Friday morning, Italian public research institute ISPRA said. The civil protection unit placed eastern Sicily under an orange alert in anticipation of the storm's arrival. "Heavy rainfall a ... read more

Read more from original source...