Research in Atmospheric Sciences at the Institute for Terrestrial and Planetary Atmospheres is centered around the following themes: (1) Climate Change and Impact, (2) Mesoscale Ensemble Forecasting, (3) Data Assimilation and Integration, (4) Model Analysis and Improvement, (5) Atmospheric Chemistry and Aerosol, (6) Atmospheric Dynamics, (7) Interaction Between Climate and Marine Biology.
Atmospheric chemistry encompasses the interaction of gases and aerosol particles with each other and with the environment. The sum of these interactions determines, in large part, the composition of Earth’s atmosphere, which therefore also changes over time. Furthermore, aerosol particles govern cloud formation with subsequent important implications for the radiative budget of the atmosphere, water vapor distribution, and the hydrological cycle. Our faculty study i) the origin of certain trace gases, with special emphasis on the large scale (hemispheric, or global) contribution from human activities, and how those contributions vary over time; ii) the potential of natural and anthropogenic aerosol particles to form ice clouds and how these particles interact with atmospheric trace gas species impacting atmospheric composition; iii) the global rate of removal of several reactive species and how this is affected by human or natural changes over time.
To address these important questions ITPA maintains two well equipped atmospheric chemistry laboratories to conduct fundamental studies pertaining to the role of gases and particles in Earth’s atmosphere. These investigations require state-of-the-art analytical tools such as gas chromatography (for concentration measurements of trace gases), isotope ratio mass spectrometry (for isotopic analysis of trace gases), conventional mass spectrometry (for compound identification), chemical ionization mass spectrometer (for chemical kinetics study), high-resolution proton-transfer time-of-flight mass spectrometer (for detection of volatile organic compounds), ice nucleation cells (for aerosol phase transition observations for temperatures as low as 180 K), and other analytical approaches. Our faculty and students also use three-dimensional computer modeling of atmospheric chemistry to interpret the observations. In addition to these laboratory and modeling based approaches, investigators from ITPA have conducted field studies in various regions, including Antarctica, Rocky Mountains, Gobi Desert, French Guiana, and South Korea.
The time evolution of the atmosphere can be described by a set of geophysical fluid dynamical laws. Atmospheric dynamics deals with the analysis of these laws to understand the mechanism of various types of atmospheric variations. The knowledge and insights gained from dynamical analyses often provide important guidance for interpreting observations and for improving numerical models. Faculty members in our Institute are studying the excitation and propagation processes of atmospheric waves in the stratosphere and the troposphere, and are developing methods to characterize these waves in observations. A better understanding of these processes can lead to their better treatments in the global general circulation models, which are known to suffer from deficiencies in these processes.
The Earth’s climate shows a great deal of natural variability as a consequence of such factors as sporadic volcanic eruptions, atmosphere-ocean variability such as El Nino, and the chaotic variability of the atmosphere. ITPA scientists are engaged in studying atmospheric data and paleo-climatic data from ice cores, as well as numerical general circulation models, to characterize and understand the nature of this variability.
Understanding natural climate variability is important for several reasons. For one, it can cause great economic losses as well as loss of human life, such as has been the case in recent hurricanes and flooding events would help in mitigating losses. Second, we will be able to identify anthropogenic effects on climate more readily if we understand natural variations in the climate record.
Global general circulation models are the standard tool used to diagnose climate processes and interactions and to project future climate changes. ITPA faculty members are pursuing research to understand and improve these models. A major limitations of the models is that the grid size is large compared to the distance-scales important to processes related to topography, clouds and vegetation. A major challenge in climate modeling is to find simple but realistic parameterizations of sub-grid scale processes, and this is one of the components of research being pursued in ITPA. Another is to gauge the significance of climate change impacts in the 21st century as simulated by global climate models. A particular focus is on storms, the changes taking place in winter storm tracks and their impact on regional climate on the east coast of North America, as well changes in the number and intensity of tropical storm and hurricanes. New York City and Long Island are vulnerable to coastal flooding. Our faculty has combined regional atmospheric models and ocean models to estimate wave heights and storm surges in these areas expected from storms of varying intensities.
Clouds Climate Interaction
A leading source of uncertainty in predicting future climate is the effect of clouds. This uncertainty arises not only because the dynamic and thermodynamic processes involved in cloud formation occur at scales smaller than climate model grid size, but also from the need to parameterize microphysical processes involved in condensation. Availability of the Stony Brook supercomputer makes it possible for our faculty to develop cloud resolving models in which the grid size is made so small that clouds can be calculated from first principles.
Synoptic and Mesoscale Meteorology
Synoptic-mesoscale research in the department focuses on improving our understanding of the meteorology around the coastal margins of North America and the atmospheric predictability in these regions. Many near-shore phenomena such as coastal fronts, land/sea breeze circulations, marine clouds/fog, and cyclonic storms interacting with coastal terrain are frequently difficult to forecast. This difficulty arises because of inadequate understanding of the physical mechanisms, deficiencies in model physics, relatively coarse resolution in operational model ensembles, and relatively sparse observations over the oceans. Using conventional data, field observations, and mesoscale models (Penn State-NCAR MM5 and Weather Research and Forecasting model), this research has explored many types of coastal atmospheric circulations and precipitation structures over both the West and East coasts of the U.S.