remote sensing

Be There: The Kuo-Nan Liou Symposium

Highlighting Key Sessions at AMS 2024

The Kuo-Nan Liou Symposium at the 104th AMS Annual Meeting will celebrate Dr. Kuo-Nan Liou (1943-2021), a giant in the field of atmospheric physics who made crucial contributions in the areas of atmospheric radiation, remote sensing, and the greenhouse impacts of clouds and aerosols. Liou (pictured at right, image courtesy of Penny Jennings), received numerous accolades during his career, including the AMS’s Carl-Gustaf Rossby Research Medal and Charney Award, and he was part of the Intergovernmental Panel on Climate Change team who received the Nobel Peace Price in 2007.

We asked Symposium Co-Chair Ping Yang, University Distinguished Professor and David Bullock Harris Chair in Geosciences at Texas A&M University, about the Symposium and Dr. Liou’s impact. Here are some of his answers:

Dr. Kuo-Nan Liou (image credit: Penny Jennings)

Why are the areas of Dr. Liou’s research so important to understand right now?

As one of the most accomplished atmospheric scientists in the world, Dr. Liou made seminal contributions to atmospheric and climate sciences in many areas, particularly in atmospheric radiation. His radiative transfer model has been widely used in weather and climate models and satellite remote sensing implementations, and thus plays a central role in determining the radiation budget of the earth-atmosphere system and cloud-aerosol-radiation interactions and feedback in a changing world.

Radiative transfer is important because almost all the energy that drives the Earth’s atmosphere and ocean currents originates from the sun. Therefore, the climate of the Earth-atmosphere system is mainly determined by the radiation balance at the top of the atmosphere and the surface since radiation is the only mechanism by which the Earth-atmosphere system gains or loses energy.

What can attendees expect from the Symposium?

This symposium honors the legacy of Dr. Kuo-Nan Liou by bringing together researchers to share knowledge, foster collaborations and address current challenges in the fields where Dr. Kuo-Nan Liou left a lasting impact. Attendees, both in-person and virtual, can benefit from gaining insights into the latest research and advancements in these areas. Session topics include “Interactions Among Climate, Radiation, Clouds, Aerosols, and Surface”, “Radiative Transfer Theory & Spectroscopy,” “Remote Sensing of Clouds, Aerosols, and Surface Properties,” and “Light Scattering and Applications.” The Symposium will provide a platform for networking and engaging with experts and a forum for disseminating cutting-edge research findings.

The Symposium will delve into the forefront issues within these research areas. Noteworthy presentation topics include the lidar remote sensing of snow depth and density, sub-millimeter-wave remote sensing of ice clouds, Tibetan Plateau snowpack loss and its connection to extreme events, and more.

The first session aligns with the central focus of the 2024 AMS Annual Meeting, “Living in a Changing Environment.” It features invited speakers Drs. Ruby Leung, Dennis Hartmann, V. Ramaswamy, Zhanqing Li, Jonathan Jiang, and Yongkang Xue. 

How did Dr. Liou influence the fields of atmospheric and climate science?

Dr. Liou’s work left a profound mark on the atmospheric and climate sciences due to his seminal contributions to radiative transfer, atmospheric optics, cloud-aerosol-radiation-climate interactions, and remote sensing. He was a pioneering researcher who demonstrated that atmospheric radiation should no longer be consigned to the fringes of meteorology, but instead should take a central place in the new world of climate science.

His book, “An Introduction to Atmospheric Radiation,” now in its second edition (with the first edition published in 1980), has been an invaluable resource for students and researchers around the world studying atmospheric radiation and its applications in climate science and remote sensing. Accepting the Rossby Medal in 2018, Prof. Liou talked about how his own early-career exposure to books like Chandrasekhar’s “Radiative Transfer” and Born & Wolf’s “Principles of Optics” spurred his innovations. For example, his simplified solutions for understanding solar and heat energy transfer problems, and his application of geometric optics to understand the scattering, absorption, and polarization properties of soot aerosols and irregular ice crystals.

He also humbly thanked his graduate students at the University of Utah and UCLA, saying, “They deserve to share, in equal measure, any recognition I have received, including this great honor from AMS.” We, the organizers of the Symposium, in turn are grateful to Dr. Liou. Along with his exceptional impact on the atmospheric sciences, he was a true role model as a leader and educator.

Kuo-Nan Liou receiving the Carl-Gustaf Rossby Research Medal at the 2018 AMS Annual Meeting and celebrating with his family, students, and colleagues. Photos provided by Liou Symposium co-chairs.

The Kuo-Nan Liou Symposium will be held Tuesday, 30 January, 2024 at the AMS 104th Annual Meeting, in Baltimore and online; it will feature invited presentations and a poster session, along with a special luncheon. Learn more about the Symposium and view the program.

The Moore Tornado from Above

The July issue of BAMS includes a feature on the new and improved imaging capabilities of the Visible Infrared Imaging Radiometer Suite (VIIRS), one of the five instruments aboard the Suomi NPP satellite. The cover montage highlights VIIRS’s expanded spectral aptitude and microscale resolution by depicting july_bams_coverthree different perspectives on the tornado outbreak that swept across the Midwest on May 20, culminating in detailed nighttime evidence of the track of  devastation in Moore, Oklahoma, as detected on May 21.
That month, the instruments on Suomi NPP were being calibrated by aircraft that in many cases flew directly under the path of the satellite. On May 20, one of these planes–an ER-2 flying above the cloud cover at approximately 65,000 feet–used the MODIS/ASTER Airborne Simulator (MASTER) to capture images of the storm that brought the EF5 tornado to Moore. The image below shows the tornado system minutes before it reached the city, and is overlaid on a Google Earth map to show the tornado location.

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(Image credit: Google Earth/Ames Airborne Sensor Facility/Rose Dominguez)

Nowhere to Hide from Snow . . . Except Florida

It snowed throughout the Northeast on Wednesday, but very few are feeling sorry for everyone in that region who had to pull out their shovels. The odds are good that you or someone you know in your state has had to deal with snow lately, too–no matter where you live in the country. According to the NWS’s National Operational Hydrologic Remote Sensing Center, which collects snow cover and depth data from ground reports and satellite observations, 49 of the 50 states currently have some snow cover…even Hawaii (this video was taken last month)! Only Florida has avoided a recent visit from Jack Frost.

Cambridge, Massachusetts, or Anytown, USA?

This isn’t an unprecedented event–in fact, all 50 states had snow on the ground last February 12th, and University of Oklahoma meteorology student and AMS student member Patrick Marsh obtained pictures from every state of that day’s snow.
But “it’s not typical,” says James Peronto, public affairs officer for the NWS, who noted that recent snowfall throughout the Southeast has created the unusually white map.
“The Southern states don’t typically get significant snow amounts through the year,” Peronto said. “It takes a special kind of weather scenario to allow that to happen.”
(This quick history lesson on Southern snow illustrates how rarely such a scenario occurs.)
NWS observations show that 70.9% of the country was covered by snow as of yesterday, compared to an average of 35% snow cover in December.
A NOAA map of U.S. snow depth and cover yesterday.

Snow cover and depth analyses like these are not just for interstate precipitation bragging rights or cabin-fever consolation. At the AMS Annual Meeting in Seattle, a number of science presentations will show the value of snow cover observations.
For example, Patricia de Rosnay et al. will present recent “major changes implemented” in the operational surface analysis of the European Center for Medium-range Weather Forecasting’s Integrated Forecasting System,” including a method of combining satellite observations of snow cover for the land surface conditions for weather modeling. (Tuesday, 25 January, 1:45 p.m.; WSCC 611).
Sujay Kumar et al. (poster 42, 9:45 a.m.-11:15 a.m., Tuesday, 25 January), will discuss snow cover from active microwave remote sensing and look at the value of assimilating snow observations from multiple satellites for hydrological modeling. They point out that “Snow conditions on the land surface are … key components of the global hydrological cycle as they play a critical role in the determination of local and regional climate.”
One way in which this is true is in regions where melted snow dominates water supply. On Thursday 27 January (4:15 p.m., WSCC 611) Randal Koster et al. will “examine how knowledge of mid-winter snow accumulation and soil moisture contributes to our ability to predict streamflow months in advance.” In an experiment with multiple land surface models,  “snowpack information by itself contributes, as expected, to skill attained in streamflow prediction, particularly in the mountainous west.” (They go on to show the additional importance of soil moisture conditions to long-lead forecasts, particularly in winter.)
Meanwhile, as a basis for the observations used in such studies, Ding Liang et al. (Poster 595; 8:30 a.m-4 p.m., Wednesday, 26 January) will delve into improvements for modeling of microwave emissivity of snow—an important step toward constructed improved snow cover data retrieved from satellite remote sensing.