My current work is on sudden stratospheric warmings, their interactions with other phenomena, their surface impacts, and their variability.
In the polar region, the stratosphere is the layer of the atmosphere from about 10 to 50 km above the surface. From roughly late August to mid-April, the winds in the mid-to-upper polar stratosphere are westerly (west to east), and they are particularly strong from about November to March. This region of westerly winds, low pressure, and cold temperatures is the stratospheric polar vortex. However, planetary waves originating below the stratosphere--due to land/sea contrast, heating anomalies, orography, etc.--can interact with and disrupt this vortex. When these disruptions are sufficiently strong, we call them sudden stratospheric warmings, due to the spike in temperature of the polar stratosphere of 20-30 Kelvin over a short period of time.
These events happen at about 30 km above the surface, but they can have important and long-lasting surface impacts. On average, in the two months following a sudden stratospheric warming, Northern Europe is colder and drier than average, and Southern Europe is warmer and wetter. There can also be effects on the east coast of the US, though these are more variable. Better understanding sudden stratospheric warmings and their surface impacts thus gives us better understanding and potentially better prediction of winter climate throughout the North Atlantic region.
Topics I have worked on include:
1. The effects of El Niño compared to neutral-ENSO on the North Atlantic region in the presence and absence of SSWs, and the impact of El Niño alone compared to that of SSWs alone. (Joint work with Gabriel Chiodo and Lorenzo Polvani)
2. The effects of ozone chemistry and transport on the mean state of the polar vortex and the frequency and surface impacts of SSWs and their particularly strong vortex counterparts. (Joint work with Gabriel Chiodo and Lorenzo Polvani)
3. Using bootstrappiing of observed events to understand variability in SSW composites, the sources of that variability, and how to evaluate models accordingly. (Joint work with Lorenzo Polvani and Clara Deser)
4. The relationship between El Niño-Southern Oscillation phase and final stratospheric warmings (the seasonal breakdown of the polar vortex), particularly their timing and surface impacts. (Joint work with Johanna Doyle and Lorenzo Polvani)
A full list of publications and presentations on this work is below. Note that authorship in atmospheric science is typically by contribution. All presenting authors on presentations are listed in italics.
Publications:
Oral Presentations:
Poster Presentations:
In the polar region, the stratosphere is the layer of the atmosphere from about 10 to 50 km above the surface. From roughly late August to mid-April, the winds in the mid-to-upper polar stratosphere are westerly (west to east), and they are particularly strong from about November to March. This region of westerly winds, low pressure, and cold temperatures is the stratospheric polar vortex. However, planetary waves originating below the stratosphere--due to land/sea contrast, heating anomalies, orography, etc.--can interact with and disrupt this vortex. When these disruptions are sufficiently strong, we call them sudden stratospheric warmings, due to the spike in temperature of the polar stratosphere of 20-30 Kelvin over a short period of time.
These events happen at about 30 km above the surface, but they can have important and long-lasting surface impacts. On average, in the two months following a sudden stratospheric warming, Northern Europe is colder and drier than average, and Southern Europe is warmer and wetter. There can also be effects on the east coast of the US, though these are more variable. Better understanding sudden stratospheric warmings and their surface impacts thus gives us better understanding and potentially better prediction of winter climate throughout the North Atlantic region.
Topics I have worked on include:
1. The effects of El Niño compared to neutral-ENSO on the North Atlantic region in the presence and absence of SSWs, and the impact of El Niño alone compared to that of SSWs alone. (Joint work with Gabriel Chiodo and Lorenzo Polvani)
2. The effects of ozone chemistry and transport on the mean state of the polar vortex and the frequency and surface impacts of SSWs and their particularly strong vortex counterparts. (Joint work with Gabriel Chiodo and Lorenzo Polvani)
3. Using bootstrappiing of observed events to understand variability in SSW composites, the sources of that variability, and how to evaluate models accordingly. (Joint work with Lorenzo Polvani and Clara Deser)
4. The relationship between El Niño-Southern Oscillation phase and final stratospheric warmings (the seasonal breakdown of the polar vortex), particularly their timing and surface impacts. (Joint work with Johanna Doyle and Lorenzo Polvani)
A full list of publications and presentations on this work is below. Note that authorship in atmospheric science is typically by contribution. All presenting authors on presentations are listed in italics.
Publications:
- J. Oehrlein, L.M. Polvani, L. Sun, C. Deser. How well do we know the surface impact of sudden stratospheric warmings? Geophys. Res. Lett., 48, 22, e2021GL095493 (2021).
- J. Oehrlein, G. Chiodo, and L.M. Polvani: The effect of interactive ozone chemistry on weak and strong polar vortex events, Atmos. Chem. & Phys., 20, 10531–10544 (2020).
- J. Oehrlein, G. Chiodo and L.M. Polvani: Separating and quantifying the distinct impacts of El Nino and stratospheric sudden warmings on North Atlantic and Eurasian wintertime climate, Atmos. Sci. Lett., 20, 7, e923 (2019).
Oral Presentations:
- J. Oehrlein: Math in the Sky: From Winter Weather to Future Climate, Olin College Research Seminar, December 2022.
- J. Oehrlein: Understanding the Atmosphere: From Winter Weather to Future Climate, Olin College Alumni Speaker Series, October 2022.
- J. Oehrlein: Math in the Sky: Studying the Stratospheric Polar Vortex, Hofstra Mathematics & Geology, Environment, and Sustainability Joint Seminar, October 2021.
- J. Oehrlein, L.M. Polvani, and C. Deser: Characterizing the Surface Impact of Sudden Stratospheric Warmings in the Context of Internal Variability, American Geophysical Union Fall Meeting, December 2020.
- J. Oehrlein: Using Climate Models to Understand Stratosphere-Troposphere Interaction (slides, video), Talk Math With Your Friends colloquium, September 2020.
- J. Oehrlein: The Other Polar Vortex: Stratospheric Impacts on North Atlantic Winter, SURF@DAWN Summer Lunch Talk, August 2020.
- J. Oehrlein, L.M. Polvani, and C. Deser: Bootstrap-Based Identification of the Surface Impact of Sudden Stratospheric Warmings, Joint Statistical Meetings, August 2020.
- J. Oehrlein, G. Chiodo, and L.M. Polvani: The Effects of Ozone Chemistry on Winter Climate, Columbia APAM Research Conference, February 2020.
- J. Oehrlein, G. Chiodo, and L.M. Polvani: Distinct impacts of El Nino and stratospheric sudden warmings on wintertime climate, Columbia APAM Research Conference, March 2019.
- J. Oehrlein, G. Chiodo, and L.M. Polvani: Separating and quantifying the distinct impacts of El Nino and stratospheric sudden warmings on North Atlantic and Eurasian wintertime climate, American Meteorological Society 99th Annual Meeting, January 2019, Phoenix, AZ.
Poster Presentations:
- J. Oehrlein, G. Chiodo, and L.M. Polvani: Separating and quantifying the distinct impacts of El Nino and stratospheric sudden warmings on North Atlantic and Eurasian wintertime climate, American Geophysical Union Fall Meeting, December 2018, Washington D.C.