Page 6 - CEGE Magazine Fall 2024

GRADUATE STUDENT RESEARCH CONT...
Monitoring global vegetation water
content and soil moisture is crucial for
understanding the intricate impacts
of climate change on ecosystems.
Specifically, it is important to comprehend
the dynamic changes in global forests,
such as the loss and gain of forested
areas, which affect the rate at which
land and atmosphere exchange radiative
energy, water, and greenhouse gasses.
This ultimately influences global climate
systems and the carbon cycle.
My research aims to improve the global
monitoring of vegetation and soil moisture
in the Northern Hemisphere during
the cold and dark periods of winter on
snow-covered surfaces. Currently, such
observations are unavailable for almost six
months.
Monitoring during snow seasons is
accomplished by developing a radiative
transfer model to simulate emissions from
snow-covered landscapes. Our model can
help satellites operating in the L-band (1.4
GHz) frequency, such as the European
Space Agency’s Soil Moisture and Ocean
Salinity satellite and NASA’s Soil Moisture
Active Passive satellite.
In Ardeshir Ebtehaj’s lab, we used our
developed model and observations
from these satellites to generate a global
dataset of vegetation and soil moisture
during winter. Validations have shown good
accuracy with other vegetation and soil
moisture proxy variables. Time series and
spatial analysis have shown the potential
of using these datasets to expand our
knowledge about the global carbon cycle
and the freeze-thaw state of the ground.
This knowledge is critical in understanding
permafrost melting due to global warming.
With this improved understanding, using
the developed physical model called the
TO-snow model, we have created a novel
deep learning framework to probabilistically
estimate the freeze-thaw state of the
landscape. These algorithms and the
generated datasets expand the potential
of the signal observed by NASA’s SMAP
satellites and improve the understanding
of landscapes to which we have limited
access.
  Last year, I served as leader and facilitator in the Institute on the
Environment’s (IonE) Graduate Leader Program. I led a group of 12 graduate
students as we conducted research focused on sustainability initiatives in the
Ecosystem and Planetary Health Cohort. Our cohort consisted of members
from social sciences, law, anthropology, mathematics, and engineering, to
name a few. In our biweekly sessions, we explored ecosystem health related
to water from a multidisciplinary perspective. 
I was born and raised in Dongying,
Shandong, China; a large part of
the city’s economy revolves around
petroleum and the nearby Shengli Oil
Field. I received my BS and MS degrees
in petroleum engineering at China
University of Petroleum (East China).
Witnessing the pollution caused by oil
extraction led me to reconsider my
professional trajectory and shift toward
addressing ecological challenges. I joined
Judy Yang’s group in 2021. Currently, I
am working on an environmental issue,
harmful algal blooms (HABs). In Yang’s
lab, we study the flocculation process
between clay particles and algal cells
  Minnesota’s numerous lakes can host smelly and dangerous algal
blooms each summer. My research focuses on using clay to remove
these harmful algal cells from water bodies. We discovered that a
synthetic clay called laponite is very efficient at removing harmful algae
like Microcystis aeruginosa, as it requires much smaller amounts be
added compared to traditional natural clays like bentonite and kaolinite.
Laponite is biodegradable, more cost-effective, and environmentally
friendly. By using laponite, we can better protect aquatic ecosystems
and reduce the health risks associated with algal toxins. 
Yuan Li, Water Resources
Advised by Judy Yang
Received the Frank Y. and
Julie C. Tsai Travel Award
Divya Kumawat, Hydrology and
Remote Sensing
Advised by Ardeshir Ebtehaj
Received the Edward Silberman Fellowship
and the Sommerfeld Fellowship
6 CEGE | CSE.UMN.EDU/CEGE