About

Marvin Geller is a professor at Stony Brook University with a research focus on atmospheric sciences. His research involves understanding various atmospheric phenomena through four distinct areas supported by grants from NSF and NASA. These areas include investigating the controls on upwelling through the tropical tropopause and its effect on stratospheric water vapor, characterizing atmospheric gravity wave activity using high-resolution radiosonde data, studying the nature of the extratropical tropopause with high vertical-resolution and conventional radiosonde data combined with modeling, and examining the influence of the quasi-biennial oscillation on deep tropical convection. Geller's work has contributed to understanding the dynamics of the atmosphere, including the stratosphere, troposphere, and related atmospheric turbulence, gravity waves, and climate interactions. He has supervised Ph.D. dissertations on topics such as mechanistic modeling of tropical upwelling, gravity waves in the troposphere and lower stratosphere, and constituent transport in data assimilation. His academic background includes a PhD from the Massachusetts Institute of Technology, and his research output encompasses numerous peer-reviewed articles, conference contributions, and collaborations, with a notable involvement in projects related to atmospheric climatology, turbulence, and climate modeling.

Research topics

• Computer Science
• Environmental science
• Physics
• Climatology
• Mechanics
• Geography
• Materials science
• Classical mechanics
• Geology
• Mathematics
• Meteorology
• Thermodynamics
• Atmospheric sciences

Selected publications

• Temperature Fluctuations of Different Vertical Scales in Raw and Processed U.S. High Vertical-Resolution Radiosonde Data

  Journal of Atmospheric and Oceanic Technology · 2025-03-01 · 1 citations

  articleOpen accessSenior author

  Abstract One-second U.S. high vertical-resolution radiosonde data (HVRRD) contain two different sets of temperature data—the raw data and the processed data. The processed data have been subject to radiation corrections, which have been well documented, and smoothing, the details of which are proprietary to the radiosonde manufacturers. We have tried to characterize this smoothing by computing the root-mean-square (rms) of normalized temperature perturbations derived from removing a second-degree polynomial fit for altitude segments (Δ z ) from 100 m to 5 km. We find that for Δ z = 100 m, rms values are larger at higher altitudes, are larger in the raw data than in the processed data, and are larger during daytime than during nighttime, for both the raw and processed data. The rms values and their daytime to nighttime differences are larger in the raw data than in the processed data. As Δ z increases toward 5 km, the geographical patterns of rms over the contiguous United States from both the raw and processed data start resembling previously published gravity wave total energy patterns obtained from the older 6-s U.S. radiosonde data. An example is shown of a discontinuity in the small-scale rms values when radiosonde instrumentation is changed, so it is concluded that small-scale temperature fluctuations will be different for different radiosonde instruments. Examples are shown of enhanced small-scale rms temperature values indicative of turbulence resulting from gravity wave critical levels and from enhanced gravity waves due to seasonal maxima in convection. Significance Statement We have characterized the variability of the raw and processed temperature profiles of the U.S. high vertical resolution radiosonde data for various vertical scales. We have argued that sources of small-scale fluctuations in the processed data include turbulence and the radiation effects which have not been accounted for in the current derivation of the processed data. Temperature fluctuations of larger scales correspond to those from gravity waves. We have shown an example of a discontinuity in small-scale fluctuations at a radiosonde station when the instrumentation was changed. These results suggest that temperature fluctuations resulting from varying amounts of solar radiation falling on the temperature sensor as the radiosonde instrumentation swings and rotates should be evaluated for each radiosonde system.

  PublisherOA PDFDOI

• Climatology of Atmospheric Unstable Layers Revisited: A Corrigendum

  Monthly Weather Review · 2024-10-01 · 1 citations

  erratum1st authorCorresponding

  Abstract We have published a recent paper on differences between temperature fluctuations of various vertical scales in raw and processed U.S. high vertical resolution radiosonde data (HVRRD). In that paper, we note that the small-scale temperature fluctuations in the raw U.S. HVRRD are significantly larger than those in the processed U.S. HVRRD and that those small-scale temperature fluctuations are much larger during daytime that during nighttime. We believe that this is due to the varying amount of solar radiation falling on the radiosonde temperature sensor as the radiosonde instrument swings and rotates. In light of these new results, we present revisions to some of our conclusions about the climatology of atmospheric unstable layers. When we repeat our calculations of atmospheric unstable layers using the processed U.S. HVRRD, we find the following. 1) The 0000/1200 UTC differences in unstable layer occurrences in the lower stratosphere that were noted in our earlier paper essentially disappear. 2) The “notch” in the deep tropics where there is a relative deficiency of thin unstable layers and a corresponding excess of thicker layers is still a feature when processed data are analyzed, but the daytime notch is less marked when the processed data were used. 3) The discontinuity in unstable layer occurrences, when there was a change in radiosonde instrumentation, is still present when processed data are analyzed, but is diminished from what it was when the raw data were analyzed. Significance Statement In a previous paper deriving the climatology of atmospheric unstable layers, we emphasized several findings. We reexamine three of the main points of that paper when processed U.S. high vertical resolution radiosonde data are analyzed instead of the raw data used in that previous paper. We find the 0000/1200 UTC differences virtually disappear in the new analysis. We find that the “notch” feature previously noted at Koror still exists, and we find that the discontinuity in unstable layers, when radiosonde instrumentation is changed, is diminished, but is still present in the new analysis.

  PublisherDOI

• The “Notch” in Unstable Layers and the Stability Minimum in the Tropics

  Journal of Climate · 2024-10-18

  article1st authorCorresponding

  Abstract In a previous paper, we identified a “notch” in unstable layers at Koror (7.3°N, 134.5°E), where there was a relative deficiency in thin unstable layers and a corresponding relative excess in thicker layers, at altitudes centered at 12 km. We hypothesized that this feature was associated with the previously identified stability minimum in the tropics at that same altitude. In this paper, we extend our studies of this notch and its association with the tropical stability minimum by examining other stations in the deep tropics and also some stations at higher latitudes within the tropics. We find that this notch feature is found at all the other radiosonde stations in the deep tropics that we examined. We also find that the annual variations in unstable layer occurrences at stations at higher latitudes within the tropics show variations consistent with our hypothesis that this notch is associated with the region of minimum stability in the tropics at altitudes centered around 12 km, in that the annual variation in this notch feature is consistent with the annual variation of minimum stability in this region. Two factors contribute to the notch feature. One is that the data quality control procedure of the analysis rejects many thin layers due to the small trend-to-noise ratio in the region of minimum stability. The other is that the cloud-top outflow, which was previously identified with the stability minimum, advects thicker unstable layers throughout the deep tropics at the altitudes of the notch. Significance Statement Previous papers have separately identified a stability minimum in the tropics and a “notch” feature in the thicknesses of unstable atmospheric layers where there are less thin unstable layers and a corresponding excess of thicker unstable layers, both at altitudes around 12 km. We previously hypothesized that these two features were associated with one another. In this paper, we examine this notch feature and the minimum in atmospheric stability at both deep tropical radiosonde stations and stations located at higher latitudes in the tropics, and we find that the annual variation of this notch feature is consistent with the latitudinal migration of the latitudes of the stability minimum. Turbulence associated with this notch feature might be significant for aircraft operations.

  PublisherDOI

• Global Distributions of Atmospheric Turbulence Estimated Using Operational High Vertical-Resolution Radiosonde Data

  Bulletin of the American Meteorological Society · 2024-12-01 · 4 citations

  article

  Abstract Atmospheric turbulence plays a key role in the mixing of trace gases and diffusion of heat and momentum, as well as in aircraft operations. Although numerous observational turbulence studies have been conducted using campaign experiments and operational data, understanding the turbulence characteristics particularly in the free atmosphere remains challenging due to its small-scale, intermittent, and sporadic nature, along with limited observational data. To address this, turbulence in the free atmosphere is estimated herein based on the Thorpe method by using operational high vertical-resolution radiosonde data (HVRRD) with vertical resolutions of about 5 or 10 m across near-global regions, provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) via the U.S. National Centers for Environmental Information (NCEI) for 6 years (October 2017–September 2023). Globally, turbulence is stronger in the troposphere than in the stratosphere, with maximum turbulence occurring about 6 km below the tropopause, followed by a sharp decrease above. Seasonal variations show strong tropospheric turbulence in summer and weak turbulence in winter for both hemispheres, while the stratosphere exhibits strong turbulence during spring. Regional analyses identify strong turbulence regions over the South Pacific and South Africa in the troposphere and over East Asia and South Africa in the stratosphere. Notably, turbulence information can be provided in regions and high altitudes that are not covered by commercial aircraft, suggesting its potential utility for both present and future high-altitude aircraft operations. Significance Statement The purpose of this study is to understand the characteristics of atmospheric turbulence in the free atmosphere, utilizing global high vertical-resolution radiosonde data (HVRRD) for recent 6 years (October 2017–September 2023). Our analysis shows that turbulence is stronger in the troposphere than in the stratosphere, with the maximum about 6 km below the tropopause. Regional analyses over 10 areas worldwide demonstrate the geographical characteristics in the troposphere and the stratosphere. This study will advance our understanding of atmospheric turbulence and help in development and validation of aviation turbulence forecasting systems for current and future high-altitude aircraft operations.

  PublisherDOI

• Kelvin–Helmholtz Instability “Tube” and “Knot” Dynamics. Part III: Extension of Elevated Turbulence and Energy Dissipation into Increasingly Viscous Flows

  Journal of the Atmospheric Sciences · 2024 · 7 citations

  Senior authorCorresponding
  • Computer Science
  • Mechanics
  • Physics

  Abstract A companion paper by Fritts et al. reviews extensive evidence for Kelvin–Helmholtz instability (KHI) “tube” and “knot” (T&K) dynamics at multiple altitudes in the atmosphere and in the oceans that reveal these dynamics to be widespread. A second companion paper by Fritts and Wang reveals KHI T&K events at larger and smaller scales to arise on multiple highly stratified sheets in a direct numerical simulation (DNS) of idealized, multiscale gravity wave–fine structure interactions. These studies reveal the diverse environments in which KHI T&K dynamics arise and suggest their potentially ubiquitous occurrence throughout the atmosphere and oceans. This paper describes a DNS of multiple KHI evolutions in wide and narrow domains enabling and excluding T&K dynamics. These DNSs employ common initial conditions but are performed for decreasing Reynolds numbers (Re) to explore whether T&K dynamics enable enhanced KHI-induced turbulence where it would be weaker or not otherwise occur. The major results are that KHI T&K dynamics extend elevated turbulence intensities and energy dissipation rates ε to smaller Re. We expect these results to have important implications for improving parameterizations of KHI-induced turbulence in the atmosphere and oceans. Significance Statement Turbulence due to small-scale shear flows plays important roles in the structure and variability of the atmosphere and oceans extending to large spatial and temporal scales. New modeling reveals that enhanced turbulence accompanies Kelvin–Helmholtz instabilities (KHIs) that arise on unstable shear layers and exhibit what were initially described as “tubes” and “knots” (T&K) when they were first observed in early laboratory experiments. We perform new modeling to explore two further aspects of these dynamics: 1) can KHI T&K dynamics increase turbulence intensities compared to KHI without T&K dynamics for the same initial fields and 2) can KHI T&K dynamics enable elevated turbulence and energy dissipation extending to more viscous flows? We show here that the answer to both questions is yes.

  PublisherDOI

• A Climatology of Unstable Layers in the Troposphere and Lower Stratosphere: Some Early Results

  Monthly Weather Review · 2021 · 9 citations

  1st authorCorresponding
  • Climatology
  • Atmospheric sciences
  • Environmental science

  Abstract The 1-s-resolution U.S. radiosonde data are analyzed for unstable layers, where the potential temperature decreases with increasing altitude, in the troposphere and lower stratosphere (LS). Care is taken to exclude spurious unstable layers arising from noise in the soundings and also to allow for the destabilizing influence of water vapor in saturated layers. Riverton, Wyoming, and Greensboro, North Carolina, in the extratropics, are analyzed in detail, where it is found that the annual and diurnal variations are largest, and the interannual variations are smallest in the LS. More unstable layer occurrences in the LS at Riverton are found at 0000 UTC, while at Greensboro, more unstable layer occurrences in the LS are at 1200 UTC, consistent with a geographical pattern where greater unstable layer occurrences in the LS are at 0000 UTC in the western United States, while greater unstable layer occurrences are at 1200 UTC in the eastern United States. The picture at Koror, Palau, in the tropics is different in that the diurnal and interannual variations in unstable layer occurrences in the LS are largest, with much smaller annual variations. At Koror, more frequent unstable layer occurrences in the LS occur at 0000 UTC. Also, a “notch” in the frequencies of occurrence of thin unstable layers at about 12 km is observed at Koror, with large frequencies of occurrence of thick layers at that altitude. Histograms are produced for the two midlatitude stations and one tropical station analyzed. The log–log slopes for troposphere histograms are in reasonable agreement with earlier results, but the LS histograms show a steeper log–log slope, consistent with more thin unstable layers and fewer thick unstable layers there. Some radiosonde stations are excluded from this analysis since a marked change in unstable layer occurrences was identified when a change in radiosonde instrumentation occurred.

  PublisherOA PDFDOI

• Characteristics of Atmospheric Turbulence Retrieved From High Vertical‐Resolution Radiosonde Data in the United States

  Journal of Geophysical Research Atmospheres · 2019-07-05 · 64 citations

  articleOpen accessSenior author

  Abstract In this study, we estimate atmospheric turbulence in the free atmosphere in terms of the Thorpe scale ( L T ) and eddy dissipation rate ( ε ) using U.S. high vertical‐resolution radiosonde data over 4 years (September 2012 to August 2016) at 68 operational stations. In addition, same calculations are conducted for 12 years (October 2005 to September 2017) at four stations among the 68 stations. These high vertical‐resolution radiosonde data have a vertical resolution of approximately 5 m and extend to an altitude of approximately 33 km, and thus, turbulence can be retrieved in the entire troposphere and lower stratosphere. There are thicker and stronger turbulent layers in the troposphere than in the stratosphere, with mean ε values of 1.84 × 10 −4 and 1.37 × 10 −4 m 2 /s 3 in the troposphere and stratosphere, respectively. The vertical structure of ε exhibits strong seasonal variations, especially in the upper troposphere and lower stratosphere, with the largest ε values in summer and the smallest in winter. In the horizontal distribution of ε , large ε is seen mainly above the mountainous region in the troposphere, but this pattern is not seen in the stratosphere. Although ε is estimated by the square of L T multiplied by the cube of the Brunt‐Väisälä frequency ( N ), the regions of large ε are matched with large L T regions where N is relatively small. For the time series of ε near the tropopause for 12 years at four stations, an annual variation is prominent at all stations without significant interannual variations. There is, however, a slightly increasing trend of ε at two stations.

  PublisherOA PDFDOI

• 100 Years of Progress in Understanding the Stratosphere and Mesosphere

  Meteorological Monographs · 2019-01-01 · 111 citations

  articleOpen access

  Abstract The stratosphere contains ~17% of Earth’s atmospheric mass, but its existence was unknown until 1902. In the following decades our knowledge grew gradually as more observations of the stratosphere were made. In 1913 the ozone layer, which protects life from harmful ultraviolet radiation, was discovered. From ozone and water vapor observations, a first basic idea of a stratospheric general circulation was put forward. Since the 1950s our knowledge of the stratosphere and mesosphere has expanded rapidly, and the importance of this region in the climate system has become clear. With more observations, several new stratospheric phenomena have been discovered: the quasi-biennial oscillation, sudden stratospheric warmings, the Southern Hemisphere ozone hole, and surface weather impacts of stratospheric variability. None of these phenomena were anticipated by theory. Advances in theory have more often than not been prompted by unexplained phenomena seen in new stratospheric observations. From the 1960s onward, the importance of dynamical processes and the coupled stratosphere–troposphere circulation was realized. Since approximately 2000, better representations of the stratosphere—and even the mesosphere—have been included in climate and weather forecasting models. We now know that in order to produce accurate seasonal weather forecasts, and to predict long-term changes in climate and the future evolution of the ozone layer, models with a well-resolved stratosphere with realistic dynamics and chemistry are necessary.

  PublisherOA PDFDOI

• Direct Numerical Simulation Guidance for Thorpe Analysis to Obtain Quantitatively Reliable Turbulence Parameters

  Journal of Atmospheric and Oceanic Technology · 2019-10-03 · 5 citations

  articleOpen access

  Abstract Thorpe analysis has been used to study turbulence in the atmosphere and ocean. It is clear that Thorpe analysis applied to individual soundings cannot be expected to give quantitatively reliable measurements of turbulence parameters because of the instantaneous nature of the measurement. A critical aspect of this analysis is the assumption of the linear relationship C = L O / L T between the Thorpe scale L T , derived from the sounding measurements, and the Ozmidov scale L O . It is the determination of L O that enables determination of the dissipation rate of turbulence kinetic energy ε . Single atmospheric and oceanic soundings cannot indicate either the source of turbulence or the stage of its evolution; different values of C are expected for different turbulence sources and stages of the turbulence evolution and thus cannot be expected to yield quantitatively reliable turbulence parameters from individual profiles. The variation of C with the stage of turbulence evolution is illustrated for direct numerical simulation (DNS) results for gravity wave breaking. Results from a DNS model of multiscale initiation and evolution of turbulence with a Reynolds number Re (which is defined using the vertical wavelength of the primary gravity wave and background buoyancy period as length and time scales, respectively) of 100 000 are sampled as in sounding of the atmosphere and ocean, and various averaging of the sounding results indicates a convergence to a well-defined value of C , indicating that applying Thorpe analysis to atmospheric or oceanic soundings and averaging over a number of profiles gives more reliable turbulence determinations. The same averaging study is also carried out when the DNS-modeled turbulence is dominated by turbulence growing from the initial instabilities, when the turbulence is fully developed, when the modeled turbulence is decaying, and when the turbulence is in a still-later decaying stage. These individual cases converge to well defined values of C , but these values of C show a large variation resulting from the different stages of turbulence evolution. This study gives guidance as to the accuracy of Thorpe analysis of turbulence as a function of the number of profiles being averaged. It also suggests that the values of C in different environments likely depend on the dominant turbulence initiation mechanisms and on the Reynolds number of the environment.

  PublisherOA PDFDOI

• The Stratosphere and Its Role in Tropical Teleconnections

  Eos · 2018-05-17 · 1 citations

  articleOpen access

  Joint SPARC Dynamics and Observations Workshop; Kyoto, Japan, 9–14 October 2017

  PublisherDOI

Recent grants

• United States High-Vertical Resolution Radiosonde Data Analysis for Gravity Waves and Tropopause Processes and Dissemination to the Science Community

  NSF · $812k · 2004–2010

• The Quasi-Biennial Oscillation (QBO) and Tropical Deep Convection

  NSF · $422k · 2008–2013

• High-Resolution Radiosonde Data, Gravity Waves, Turbulence, and the Extratropical Tropopause

  NSF · $703k · 2011–2016

Frequent coauthors

• V. A. Yudin

  32 shared

• Victor L. Dvortsov

  31 shared

• S. P. Smyshlyaev

  Russian State Hydrometeorological University

  27 shared

• V. Yudin

  Catholic University of America

  25 shared

• Ling Wang

  G & A Technical Software (United States)

  24 shared

• Minghua Zhang

  22 shared

• B. Khattatov

  Numerica Corporation (United States)

  20 shared

• Tiehan Zhou

  Goddard Institute for Space Studies

  16 shared

Education

• PhD, Meteorology

  Massachusetts Institute of Technology

  1969

Awards & honors

• Nobel Peace Prize (2007)