Joey Knisely

Department of Atmospheric and Oceanic Sciences

University of Maryland

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About Me

I'm Joey Knisely, a PhD candidate at the Department of Atmospheric and Oceanic Sciences at the University of Maryland, College Park. I currently work with Dr. Jon Poterjoy in the Weather-Chaos Research Group. I am also a recipient of the Weather Program Office (WPO) Innovation for Next Generation Scientists (WINGS) Dissertation Fellowship, supported by NOAA WPO and administered by UCAR's Cooperative Programs for the Advancement of Earth System Science. My research seeks to advance the science of tropical cyclone prediction through more accurate treatment and assimilation of satellite radiance measurements in the Hurricane Analysis and Forecast System (HAFS), NOAA's operational numerical weather model for tropical cyclones.

I have a B.S. in Physics with a minor in Mathematics from Pennsylvania State University . After my undergrad, I spent several years working odd jobs, including in high-end kitchens and environmental chemical testing labs, before joining my PhD program in 2019.

On the weekends, you can find me hiking, biking, trail running, or otherwise enjoying the outdoors. I have a passion for cooking, and wish to travel and taste cuisines from all around the world. I love electronic music, hip hop, and jazz fusion, and enjoy craft beers and dry red wines. The next time you're in a virtual meeting with me, look out for my cats Maya and Maggi, who love interrupting their papa's work.

Download CV (coming soon)
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Research

Tropical cyclones are particularly difficult to model due to a number of factors, including the complex physical processes between ocean and atmosphere, which are not wholly understood and therefore difficult to model; the scale of these storm systems; as well as the unpredictable nature of rapid intensification.

These challenges are compounded by the nature of tropical cyclone formation and evolution over remote areas of the Atlantic and Pacific oceans, for which we have very few in-situ measurements. As a result, numerical weather models rely heavily on high resolution microwave and infrared radiance measurements, which are collected via satellite instruments, such as the advanced microwave sounding unit aboard NOAA polar-orbiting satellites.

However, a significant challenge remains: observation error. Satellite instruments do not directly observe atmospheric variables, instead collecting data on electromagnetic energy emitted from Earth's surface and atmosphere from which useful variables such as temperature and humidity are derived from.This derivation requires a radiative transfer model, and is highly complex and can introduce complicated observation errors. Furthermore, observation errors can arise from other sources, such as improper calibration of the instrument itself.

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Track Error Verification, Control (a) vs Online Bias Correction (b), for AL20, Hurricane Teddy. The blue lines represent forecasts generated early in the model time span, transitioning to red as forecast time progresses. Black represents the best track estimate.

As a result, radiance measurements must be corrected of biases prior to assimilation into numerical weather models. Since these biases depend on specific weather conditions, we can produce statistical models that are constructed based on our physical knowledge of these bias sources. In this way, we are able to leverage our imperfect knowledge of atmospheric conditions to form a relatively accurate estimate of bias.

That being said, Knisely and Poterjoy (2023) show that the effectiveness of these bias correction methods varies widely depending on the weather model they are trained on. It also highlights the importance of uninterrupted basin-wide data assimilation methodologies, as opposed to more limited, ad-hoc model initialization steps common in operational hurricane models.

This work serves as both a proof of concept and a motivation for ongoing research exploring continuous basin-wide data assimilation with high resolution ensembles with HAFS. With this research, we investigate new ensemble data assimilation techniques that aim to transition HAFS into a fully probabilistic prediction system. Ultimately, we seek to understand how these methods can improve tropical cyclone forecasting, as well as how they may synergize with the bias correction methodology outlined by Knisely and Poterjoy (2023).

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Teaching

I have been a TA for AOSC 200 (Weather and Climate) for Dr. Tim Canty and taught AOSC 201 (Weather and Climate Lab) for three semesters (Fall 2019, Spring 2020, Fall 2020).

I also helped organise our weekly AOSC departmental seminars and lead the "Meet the Speaker" sessions.

 

 

 

 

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