Juan M. Lora
· Associate Professor of Earth & Planetary SciencesVerifiedYale University · Department of Earth and Planetary Sciences
Active 1976–2026
About
Juan Lora is an Assistant Professor of Earth and Planetary Sciences who leads the research group associated with the Titan Atmospheric Model (TAM). He has overseen the development and application of TAM since its creation in 2014. His research primarily focuses on Titan, Saturn's largest moon, with particular attention to its methane cycle, atmospheric circulation, surface–atmosphere interactions, and paleoclimate. Through his leadership and expertise, Lora has contributed to advancing the understanding of Titan's complex atmospheric processes and climate dynamics.
Research topics
- Environmental science
- Geology
- Geography
- Meteorology
- Computer Science
- Political Science
- Oceanography
- Atmospheric sciences
- Physics
- Waste management
- Earth science
- Engineering
- Law
- Library science
- Climatology
- Geomorphology
- Astrobiology
Selected publications
Open MIND · 2026-01-01
datasetPlease cite as: Charlene Detelich, Una Schneck, Alexander Hayes, Milan Curcic, Rose Palermo, Andrew Ashton, J. Taylor Perron, Juan Lora, Jordan Steckloff. (2026) Data and scripts from Modeling the Seasonality of Wind-Driven Hydrocarbon Waves in Titan's Polar Lakes. [dataset] Cornell University Library eCommons Repository. https://doi.org/10.7298/pz39-p920
Open MIND · 2026-02-15
datasetSenior authorHere is archived the Titan Atmospheric Model (TAM) data analyzed in "Interaction of trace species and three-dimensional circulation in Titan's middle atmosphere" (Lombardo & Lora, 2026). Questions should be directed to --- nicholas.lombardo@yale.edu, Updated Feb 15 2026 This archive includes arrays for:: jgr_C2H6 -- simulated C2H6-like molecule jgr_C2H4 --- simulated C2H4-like molecule jgr_HCN -- simulated HCN-like molecule jgr_HC3N --- simulated HC3N-like molecule jgr_TEMP --- simulated temperature jgr_U --- simulated zonal wind jgr_PV --- simulated Ertel scaled potential vorticity The shape of each file is (672, 50, 32), corresponding to time, pressure, and latitude. The values of the dimensions are in the respective jgr_ls (degrees of solar longitude), jgr_p (Pascal), and jgr_lat (degrees North) array files.
Atmospheric rivers and energy transport in a hierarchy of idealized models
2026-03-14
articleOpen accessSenior authorCorrespondingAtmospheric rivers (ARs) play a major role in both global moisture and energy transport. There has been substantial research exploring the sources and pathways of moisture in these features, which often cooccur with extratropical cyclone systems and spatially overlap with the cyclone’s warm conveyor belt. However, how these features contribute to the convergence and transport of energy at a local and global scale is less well understood. Our new work uses Isca, an idealized modeling framework, to construct a hierarchy of models with varying complexity. By varying the radiation scheme from a simple, gray radiation scheme, to a scheme including water vapor feedbacks, to a full radiative transfer scheme, this model hierarchy allows us to use mechanism denial to better understand the physical processes that govern the AR size, frequency, and their role in energy convergence and transport. We examine how moisture and energy transport change throughout the AR lifecycle, and with varying levels of CO2 forcing. We also present a new, threshold-free AR identification method that performs equally well across a variety of warming and cooling experiments, without arbitrary adjustments of thresholds, allowing us to accurately assess changes to AR frequency, size, and energy and moisture transport in a variety of climate states. This work provides new insight into the nature of ARs, their internal structure and lifecycles, and their role in the global energy budget.
Zenodo (CERN European Organization for Nuclear Research) · 2026-02-15
datasetOpen accessSenior authorHere is archived the Titan Atmospheric Model (TAM) data analyzed in "Interaction of trace species and three-dimensional circulation in Titan's middle atmosphere" (Lombardo & Lora, 2026). Questions should be directed to --- nicholas.lombardo@yale.edu, Updated Feb 15 2026 This archive includes arrays for:: jgr_C2H6 -- simulated C2H6-like molecule jgr_C2H4 --- simulated C2H4-like molecule jgr_HCN -- simulated HCN-like molecule jgr_HC3N --- simulated HC3N-like molecule jgr_TEMP --- simulated temperature jgr_U --- simulated zonal wind jgr_PV --- simulated Ertel scaled potential vorticity The shape of each file is (672, 50, 32), corresponding to time, pressure, and latitude. The values of the dimensions are in the respective jgr_ls (degrees of solar longitude), jgr_p (Pascal), and jgr_lat (degrees North) array files.
Propagation and Periodicity of Mars's Northern Annular Mode Modulates the Dust Cycle
Geophysical Research Letters · 2025-03-18
articleOpen accessAbstract We document the propagation of annular modes—zonally symmetric patterns of variability—in Mars's atmosphere using a reanalysis dataset. Mars's Northern Annular Mode (MNAM) sees anomalies of zonal‐mean zonal wind emerge near the subtropics and migrate poleward with a period of 150 days, similarly to Earth's Southern Annular Mode. The mechanism of propagation involves the interaction of the two leading empirical orthogonal functions that define the MNAM. Moreover, the propagation encourages alternating bands of surface wind stress to migrate polewards with a 150‐day period. In addition, a 150‐day periodicity in anomalous column dust optical depth most likely emerges in response to extrema of the MNAM. The combination of the impact of the MNAM's internally forced periodicity on the surface wind stress and the seasonal cycle may contribute to the inter‐annual variability of global dust events, as suggested by a Monte Carlo estimate that correctly approximates the observed incidence of global dust events.
Past aquifer responses to climate recorded by fossil groundwater
Science Advances · 2025-06-11 · 1 citations
articleOpen accessBillions of people rely upon groundwater for drinking water and agriculture, yet predicting how climate change may affect aquifer storage remains challenging. To gain insight beyond the short historical record, we reconstruct changes in groundwater levels in western North America during the last glacial termination (LGT, ~20 to 11 thousand years ago) using noble gas isotopes. Our reconstructions indicate remarkable stability of water table depth in a Pacific Northwest aquifer throughout the LGT despite increasing precipitation, closely matching independent Earth system model (ESM) simulations. In the American Southwest, ESM simulations and noble gas isotopes both suggest a pronounced LGT decline in water table depth in in response to decreasing precipitation, indicating distinct regional groundwater responses to climate. Despite the hydrologic simplicity of ESMs, their agreement with proxy reconstructions of past water table depth suggests that these models hold value in understanding groundwater dynamics and projecting large-scale aquifer responses to climate forcing.
Journal of Geophysical Research Atmospheres · 2025-01-02 · 3 citations
articleOpen accessAbstract Atmospheric rivers (ARs) are filamentary structures within the atmosphere that account for a substantial portion of poleward moisture transport and play an important role in Earth's hydroclimate. However, there is no one quantitative definition for what constitutes an atmospheric river, leading to uncertainty in quantifying how these systems respond to global change. This study seeks to better understand how different AR detection tools (ARDTs) respond to changes in climate states utilizing single‐forcing climate model experiments under the aegis of the Atmospheric River Tracking Method Intercomparison Project (ARTMIP). We compare a simulation with an early Holocene orbital configuration and another with CO 2 levels of the Last Glacial Maximum to a preindustrial control simulation to test how the ARDTs respond to changes in seasonality and mean climate state, respectively. We find good agreement among the algorithms in the AR response to the changing orbital configuration, with a poleward shift in AR frequency that tracks seasonal poleward shifts in atmospheric water vapor and zonal winds. In the low CO 2 simulation, the algorithms generally agree on the sign of AR changes, but there is substantial spread in their magnitude, indicating that mean‐state changes lead to larger uncertainty. This disagreement likely arises primarily from differences between algorithms in their thresholds for water vapor and its transport used for identifying ARs. These findings warrant caution in ARDT selection for paleoclimate and climate change studies in which there is a change to the mean climate state, as ARDT selection contributes substantial uncertainty in such cases.
The Titan Middle Atmosphere Intercomparison Project
2025-07-09
preprintOpen accessCorrespondingThe atmosphere of Titan, the largest moon of Saturn, is unique in the Solar System. Like Earth, its atmosphere is mostly composed of molecular nitrogen, though unlike Earth, there is no molecular oxygen and instead the second most abundant molecule is methane. The interactions between the products of the photodissociation of these two dominant molecules give rise to a complex suite of hydrocarbons (molecules of the form CxHy) and nitriles (CxHyNz) [1]. Continued reactions (through their collision and agglomeration) between these species ultimately lead to Titan’s characteristic orange haze, which shields Titan’s surface from most shortwave sunlight. Akin to the absorption of ultraviolet light by Earth’s stratospheric ozone, shortwave radiative heating by Titan’s haze and methane leads to the formation of Titan’s stratopause, the local thermal maximum that separates the stratosphere (about 40 to 250 km above the surface) and mesosphere (about 250 to 600 km above the surface).Across all latitudes, the zonal winds in Titan’s middle atmosphere are westerly, exclusively blowing from the west towards the east, and have been inferred to reach speeds up to ~280 m/s [2,3,4]. This is in stark contrast to the zonal winds of Earth’s stratosphere, which include both westerly and easterly blowing winds. The maintenance of Titan’s stratospheric superrotation is thought to be by the Gierasch-Rossow-Williams mechanisms [5,6]: Zonal angular momentum is delivered to the stratosphere from ascending motion from the surface and then transported to the high latitude by the meridional circulation; this transport is then balanced by the transport of zonal momentum equatorward by atmospheric eddies, likely made up of Rossby-Kelvin waves [7,8,9].Trace molecules (e.g., C2H6, C2H4, C2H2, HCN) in Titan’s stratosphere are enriched above the winter pole, in some cases by several orders of magnitude [10,11]. The enrichment is generally thought to be driven by the descending branch of Titan’s meridional overturning circulation delivering molecules from their high-altitude source region into the lower stratosphere. Once delivered to the high-latitude stratosphere, the molecules are thought to be trapped by the strong stratospheric jet. Some molecules (e.g., C2H6) exhibit ‘tongues’ extending away from the high latitude, suggestive of mixing processes transporting high latitude air into the mid latitudes [12]. This, however, has yet to be confirmed.In this presentation, we directly compare three Titan general circulation models (GCM) to determine the characteristics of Titan’s middle atmosphere that are robustly present across different model assumptions and parameterizations. Included in this intercomparison are the Titan Atmospheric Model (TAM, [13]), Titan Planetary Climate Model (Titan PCM, [14]), and TitanWRF [9]. This intercomparison of fully three-dimensional GCMs aims to provide the first multi-model resource to explain the observed seasonal-scale changes in Titan’s middle atmospheric thermal, dynamical, and compositional structure.References[1] Vuitton et al., Icarus, 2019[2] Sharkey et al., Icarus, 2021[3] Achterberg, PSJ, 2023[4] Vinatier et al., A&A, 2020[5] Gierash, JAS, 1975[6] Rossow & Williams, JAS, 1979[7] Lombardo & Lora, JGR: Planets, 2023[8] Lewis et al., PSJ, 2023[9] Lian et al., Icarus, 2025[10] Teanby et al., GRL, 2019[11] Mathe et al., Icarus, 2020[12] Shultis et al., PSJ, 2022[13] Lombardo & Lora, Icarus, 2023[14] de Batz de Trenquelléon, et al., PSJ, 2025
2025-07-09
preprintOpen accessSenior authorCorrespondingUranus is a unique world in the solar system, with its extreme obliquity and low apparent internal heat flux raising compelling atmospheric and climate dynamics questions. Observations reveal an altogether different circulation regime from the gas giants, with a single mid-latitude prograde jet in each hemisphere and a weak subrotating equatorial jet. Indications of a warm equator and poles with cool mid-latitudes, as well as density gradients associated with nonuniform abundance of methane and hydrogen sulfide, can be linked to vertical motion in the upper atmosphere and vertical structure in the jets (Fletcher et al., 2021). Multiple haze and aerosol layers are likely present as well, which are a major component of the atmosphere’s radiation budget (Irwin et al., 2022). All these observations suggest a complex climate system and global circulation, but they do not provide an especially clear or self-consistent model. This motivates greater observational efforts which are ongoing, particularly with the development of the Uranus Orbiter and Probe mission. However, such efforts will take a long time to get off the ground, and long-term variability in the Uranus climate system cannot be studied directly with observations due to the long orbital period and radiative timescales. Thus, global climate modeling is necessary to fully understand the dynamics of the Uranian climate.Here we present progress on the development of a comprehensive general circulation model (GCM) for Uranus to investigate climatic processes. The GCM is built on the GFDL Finite-Volume Cubed-Sphere (FV3) dynamical core, which solves the nonhydrostatic Euler equations for a shallow atmosphere on a highly parallelizable finite-volume grid (Harris et al., 2021). We have made modifications to incorporate Uranus’s planetary constants, extend the model bottom to higher pressures, and introduce parameterizations of unresolved physical processes relevant for Uranus. These include several options, of varying complexity, to parameterize radiative heating and cooling: Newtonian cooling; a two-stream gray radiation scheme based on Liu & Schneider (2010); and a correlated-k radiative transfer scheme modified from Lora et al. (2015), including full opacity contributions from molecular and collision-induced absorption, Rayleigh scattering, and scattering and absorption by aerosol layers as described by Irwin et al. (2022).Our work focuses on understanding jet formation and overturning circulations driven by baroclinic eddies and momentum transport in Uranus's atmosphere. The connection between this global circulation and chemical tracer gradients—particularly methane and hydrogen sulfide—is another area of interest, as is the influence of Uranus’s extreme seasonal forcing, which remains poorly understood. The hierarchy of simulation complexity enabled by our various model configurations will enable us to diagnose the dominant mechanisms controlling Uranus's climate. The temperature and wind structures simulated with a simple Newtonian cooling case, which show the development of mid-latitude prograde jets and an equatorial retrograde jet, are consistent with observations (Figure 1). The prograde jets are eddy-driven as indicated by the distribution of eddy angular momentum flux divergence, which reveals deposition of prograde angular momentum into the mid-latitudes by baroclinic Rossby waves. Prograde angular momentum is fluxed out of low latitudes in the process, resulting in a weak subrotating jet centered on the equator. Associated with these jets are three meridional overturning cells. Separately, the correlated-k radiative transfer scheme, including all opacity contributions, an enthalpy-conservative dry convective adjustment scheme, and a thermosphere heat conduction scheme (Milcareck et al., 2024) produces a Uranus-like vertical temperature profile (Figure 2) between 10 bar and the lower stratosphere, with a too-cold upper stratosphere, consistent with previous modeling challenges. We will show progress in integrating this correlated-k radiative transfer scheme with the GCM dynamics, with simulations including full seasonally varying radiation, a weak intrinsic heat flux, and a parameterization of interior drag.Figure 1: Zonal and time mean temperature (top) and zonal wind (bottom) for Newtonian cooling simulation over one Uranus year.Figure 2: Radiative-convective equilibrium temperature profiles from correlated-k radiative transfer scheme. Blue curve shows global mean simulation, green shows equatorial profile, red shows Orton et al. (2014) observations. References Fletcher, L. N., de Pater, I., Orton, G. S., Hofstadter, M. D., Irwin, P. G. J., Roman, M. T., & Toledo, D. (2020). Ice Giant Circulation Patterns: Implications for Atmospheric Probes. Space Science Reviews, 216(2), 21. https://doi.org/10.1007/s11214-020-00646-1Irwin, P. G. J., Teanby, N. A., Fletcher, L. N., Toledo, D., Orton, G. S., Wong, M. H., Roman, M. T., Pérez-Hoyos, S., James, A., & Dobinson, J. (2022). Hazy Blue Worlds: A Holistic Aerosol Model for Uranus and Neptune, Including Dark Spots. Journal of Geophysical Research: Planets, 127(6), e2022JE007189. https://doi.org/10.1029/2022JE007189Harris, L., Chen, X., Putman, W., Zhou, L., & Chen, J.-H. (2021). A Scientific Description of the GFDL Finite-Volume Cubed-Sphere Dynamical Core. Geophysical Fluid Dynamics Laboratory. https://repository.library.noaa.gov/view/noaa/30725Liu, J., & Schneider, T. (2010). Mechanisms of jet formation on the giant planets. Journal of the Atmospheric Sciences, 67(11), 3652–3672. https://doi.org/10.1175/2010JAS3492.1Lora, J. M., Lunine, J. I., & Russell, J. L. (2015). GCM simulations of Titan’s middle and lower atmosphere and comparison to observations. Icarus, 250, 516–528. https://doi.org/10.1016/j.icarus.2014.12.030Milcareck, G., Guerlet, S., Montmessin, F., Spiga, A., Leconte, J., Millour, E., Clément, N., Fletcher, L. N., Roman, M. T., Lellouch, E., Moreno, R., Cavalié, T., & Carrión-González, Ó. (2024). Radiative-convective models of the atmospheres of Uranus and Neptune: Heating sources and seasonal effects. Astronomy & Astrophysics. http://arxiv.org/abs/2403.13399Orton, G. S., Moses, J. I., Fletcher, L. N., Mainzer, A. K., Hines, D., Hammel, H. B., Martin-Torres, J., Burgdorf, M., Merlet, C., & Line, M. R. (2014). Mid-infrared spectroscopy of Uranus from the Spitzer infrared spectrometer: 2. Determination of the mean composition of the upper troposphere and stratosphere. Icarus, 243, 471–493. https://doi.org/10.1016/j.icarus.2014.07.012
Journal of Climate · 2025-06-27
articleSenior authorAbstract The poleward extent of Earth’s zonal-mean Hadley cells varies across seasons and years, which would be nice to capture in a simple theory. A plausible, albeit diagnostic, candidate from Hill et al. combines the conventional two-layer, quasigeostrophic, baroclinic instability-based framework with a less conventional assumption that each cell’s upper-branch zonal winds are suitably captured by a single, cell-wide Rossby number, with meridional variations in the local Rossby number neglected. We test this theory against ERA5 reanalysis data, finding that it captures both seasonal and interannual variations in the Hadley cell zonal winds and poleward extent fairly well. For the seasonal cycle of the Northern Hemisphere (NH) cell poleward edge only, this requires empirically lagging the prediction by 1 month, for reasons unclear to us. In all cases, the bulk Rossby number value that yields the most accurate zonal wind fields is approximately equal to the actual, diagnosed cell-mean value. Variations in these cell-mean Rossby numbers, in turn, predominantly drive variations in each cell’s poleward extent. All other terms matter much less—including the subtropical static stability, which, by increasing under global warming, is generally considered the predominant driver of future Hadley cell expansion. These results argue for developing a predictive theory for the cell-mean Rossby number and for diagnosing its role in climate model projections of future Hadley cell expansion.
Recent grants
NSF · $172k · 2015–2017
NSF · $241k · 2019–2023
NSF · $41k · 2021–2024
Frequent coauthors
- 229 shared
P. Corlies
Spectral Sciences (United States)
- 214 shared
Sarah M. Hörst
Johns Hopkins University
- 207 shared
Anezina Solomonidou
- 201 shared
Jordan K. Steckloff
The University of Texas at Austin
- 198 shared
Jani Radebaugh
- 196 shared
S. Birch
University of Baltimore
- 190 shared
S. Rodríguez
- 173 shared
E. P. Turtle
Johns Hopkins University Applied Physics Laboratory
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