Atmospheric Science

Atmospheric scientists at JPL conduct fundamental research, employing end-to-end expertise in observations from multiple vantage points to better characterize Earth’s atmosphere and improve models of regional and global climate to reduce uncertainties in projections of future change.  We provide scientific leadership in conceiving, developing, implementing, and operating JPL’s climate and atmosphere observing experiments.

Cross-cutting themes in atmospheric research at JPL include:

  • Tropospheric chemistry – Remote sensing measurements to investigate local air quality and the impacts of long-range transport of pollution, especially from large cities and biomass burning, on global chemistry and climate
  • Stratospheric chemistry – Remote sensing measurements to enhance understanding of Earth atmospheric chemistry and dynamics from the upper troposphere to the mesosphere, including the stratospheric ozone layer and its links to climate
  • Aerosols and clouds – Advanced techniques for remote sensing of aerosols and clouds, critical components of the climate system
  • Satellite data analysis and retrieval algorithms – Extraction of geophysical information from raw satellite observations
  • Ground-based, aircraft, and balloon-borne atmospheric composition measurements –International field campaigns for science and validation of remote sensing measurements, development and demonstration of new measurement capabilities, and long term climate data records
  • Laboratory kinetics and spectroscopy – Critical laboratory measurements of reaction rates and details of gas absorption features that support a broad range of activities in Earth and planetary science and astrophysics
  • Climate forcing and feedback – Space- and ground-based measurements of atmospheric CO2; analysis of how water vapor, clouds, and aerosols interact
  • Improving the reliability of climate model projections – Theory, simulation and the utilization of multi-platform satellite remote sensing data to address critical questions related to modeling regional and global climate and reducing uncertainty in climate models 

 


Spaceborne Remote Sensing

 

JPL is responsible for ensuring the quality of and analyzing the data collected from various instruments on NASA’s Earth-observing spacecraft. Scientists at JPL use satellite observations of the climate system to address critical questions related to modeling regional and global climate, understanding climate feedbacks, predicting climate change, reducing uncertainties in climate models and their projections, and developing new observing system strategies to measure climate forcing and response as well as poorly characterized processes to improve climate prediction.

 

Tropospheric Emission Spectrometry

TES mesaurements
Ozone and Carbon Monoxide measurements from the Tropospheric Emission Spectrometer (TES) instrument.
 

Work performed in this area centers on the data returned from the Tropospheric Emission Spectrometer (TES) experiment on the EOS-Aura satellite. TES is an infrared Fourier Transform Spectrometer designed to make global measurements of tropospheric ozone and its chemical precursors.

Air pollution species that TES measures include ozone and carbon monoxide, as well as ammonia, and methanol, formic acid and peroxyacetyl nitrate. Global mid-tropospheric carbon dioxide measurements have been derived from TES, as well as the instantaneous radiative forcing of ozone, and global methane fields. Measurements of the isotope of water vapor, HDO, are used to study the water cycle and atmospheric dynamics.

 

Microwave Atmospheric Science

MLS measurements
Microwave Limb Sounder measurements of stratospheric ozone and chlorine monoxide, the primary agent of ozone destruction in the stratosphere, during the Arctic winter of 2010/2011, when an unprecedented degree of chemical ozone loss occurred.
 

The Microwave Limb Sounder (MLS) experiments measure naturally occurring microwave thermal emission from the limb (edge) of Earth's atmosphere to remotely sense vertical profiles of a large suite of atmospheric trace gases from the upper troposphere, through the stratosphere, and into the mesosphere, as well as temperature and cloud ice water content.  The first MLS satellite experiment was on the Upper Atmosphere Research Satellite (UARS), launched in 1991 to assess the chlorine threat to stratospheric ozone. The second, EOS MLS, is on the Aura satellite, launched on July 15, 2004.  The overall objective of these experiments is to provide information that will help improve our understanding of Earth's atmosphere and global change.

Specific scientific goals of Aura MLS are to:

  1. Track whether the stratospheric ozone layer is recovering as expected
  2. Quantify aspects of how atmospheric composition affects climate
  3. Provide information on pollution in the upper troposphere

 

Aerosol and Cloud Science

MISR measurements
Multi-angle Imaging SpectroRadiometer measurements of aerosols over Africa, showing large amounts of airborne Saharan desert dust.
 

The Multi-angle Imaging SpectroRadiometer (MISR) instrument onboard the Terra spacecraft collects multi-angle images at visible and near-infrared wavelengths, enabling it to measure the heights of clouds and smoke, dust, and volcanic ash plumes, retrieve height-resolved tropospheric wind vectors, and determine the abundance and types of airborne particles known as aerosols. MISR’s nine cameras, observing the Earth at nine different angles of view, have been collecting global data since 2000.

A new generation of satellite instrument, known as the Multiangle SpectroPolarimetric Imager (MSPI) is currently being developed. An airborne prototype, Airborne Multi-angle Spectro Polarimetric Imager (AirMSPI), has been flying aboard NASA’s ER-2 high-altitude research aircraft since 2010. This instrument extends the spectral range of the multi-angle observations into the ultraviolet and also measures the polarization of light scattered by aerosols and clouds. These new capabilities provide additional details about the sizes and shapes of these airborne particles, which is important for determining their climatic and environmental impacts.

 

The Hydrologic Cycle in the Atmosphere

AIRS measurements
Atomospheric Infrared Sounder total precipitable water vapor (mm), May 2009.
 

Work in the Atmospheric Physics and Weather group is focused on “moist thermodynamics” and the water cycle in the atmosphere as measured by sounders and related sensors, such as the Atmospheric Infrared Sounder (AIRS) and the Advanced Microwave Sounding Unit (AMSU), both operating on the Aqua satellite. Key parameters in this research include the vertical distribution of temperature and water vapor, cloud top temperature and height, and sea surface temperature. Related observations from the Moderate Resolution Imaging Spectrometer (MODIS), also on Aqua, and CloudSat are used to complement the cloud picture. The group also uses observations from the Global Precipitation Measurement mission (GPM) and similar sensors for another key element of the atmospheric water cycle. These observations are used to analyze and understand atmospheric weather and climate processes and assess the performance of forecast models. They are also used to develop applications in areas such as “meteorological drought”, air quality related to temperature inversions, and aviation hazards related to very cold conditions and volcanic eruptions. The latter is made possible because infrared sounders also detect trace gases, such as SO2, as well as dust and ash.

 

Carbon Cycle Science from Space

Orbiting Carbon Observatory (OCO)-2 is NASA’s first dedicated Earth remote sensing satellite to study atmospheric carbon dioxide from space. By measuring reflected sunlight, OCO-2 collects space-based global measurements of atmospheric CO2 with the precision, resolution, and coverage needed to characterize its sources and sinks on regional scales. OCO-2 is also able to quantify CO2 variability over the seasonal cycle year after year. OCO-2 collects a million high-resolution measurements per day, and these measurements are combined with data from the ground-based network to provide scientists with the information that they need to better understand the processes that regulate atmospheric CO2 and its role in the carbon cycle.

Though OCO-2 launched in July 2014 as a standalone mission, preparations are underway to use a spare OCO-2 instrument to create the OCO-3 mission on the International Space Station (ISS). OCO-3 is planned for installation on the ISS in late 2016, to continue NASA's remote measurements of CO2 with reflected sunlight.

 


Suborbital Atmospheric Measurements

 

Researchers at JPL perform many suborbital remote and in situ measurements of the atmosphere and routinely support field campaigns.

 

Mark IV Interferometer

The Mark IV interferometer team uses a mid-infrared Fourier transform interferometer to measure the atmosphere using the Sun as a source. The interferometer can be deployed in a stratospheric balloon gondola, on aircraft, or on the ground to measure  over 30 different atmospheric gases simultaneously.

 

Submillimeter Limb Sounder (SLS) instrument

Balloon measurement
Figure above shows high-resolution limb emission spectra of HCl, O3 and other gases near 630 GHz at five limb tangent heights taken during a balloon flight in September 2011.
 

The Submillimeterwave Limb Sounder (SLS) measures spectrally resolved thermal emission from Earth's atmosphere to determine abundance profiles of several trace gases including BrO, HO2, O3, HCl and ClO. The SLS is a passive receiver fitted with a cryogenic superconductor-insulator-superconductor (SIS) mixer and a state-of-the-art high spectral resolution (375 MHz) broad bandwidth (3 GHz) digital spectrometer.

 

CARVE

CARVE measurements
Left: Seasonal variations in atmospheric carbon dioxide (CO2) concentrations observed during all 2012 CARVE flights. Photosynthetic uptake decreases concentrations in June, July and August, while respiration (decay) increases signals in May and September.
Right: Seasonal variations in atmospheric methane (CH4) concentrations observed during all 2012 CARVE flights. Concentrations increase throughout the growing season as the soils warm, peaking in August and September (note the significant increase in values > 1950 ppb in these months).
 

The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE) is a NASA Earth Ventures (EV-1) investigation designed to quantify correlations between atmospheric and surface state variables for the Alaskan terrestrial ecosystems through intensive seasonal aircraft campaigns, ground-based observations, and analysis sustained over a 5-year mission. CARVE bridges critical gaps in our knowledge and understanding of Arctic ecosystems, linkages between the Arctic hydrologic and terrestrial carbon cycles, and the feedback from fires and thawing permafrost. CARVE’s objectives are to:

  1. Directly test hypotheses attributing the mobilization of vulnerable Arctic carbon reservoirs to climate warming
  2. Deliver the first direct measurements and detailed maps of CO2 and CH4 sources on regional scales in the Alaskan Arctic
  3. Demonstrate new remote sensing and modeling capabilities to quantify feedbacks between carbon fluxes and carbon cycle-climate processes in the Arctic

The CARVE team flew 32 sorties and over 200 science flight hours in 2012. These flights revealed regional-scale methane concentration enhancements over 200 ppb covering more than 10,000 km2 on the North Slope of Alaska as well as the monthly behavior of carbon dioxide and methane across the Alaskan Arctic.

 

Lidar

LIDAR measurements
During tropopause folding events, the origin of the air masses is inferred from the anticorrelation relation between measured ozone (left) and water vapor (right), obtained from lidar sounding. Dry, ozone-rich air comes from middle or high latitudes (north of the subtropical jet), while moist and ozone-poor air comes from the tropical upper troposphere (south of the subtropical jet). Regions where the anticorrelation breaks down (e.g. 12 km near 12:00 UT) suggest mixing within the jetstream.
 

Lidar (for LIght Detection and Ranging) is an active remote sensing technique that uses the properties of light scattering by atmospheric molecules and particles. The JPL Table Mountain Facility (TMF) Lidar Group uses it to measure high-resolution profiles of stratospheric ozone and aerosols (15-50 km), tropospheric ozone (3-25 km), temperature (15-90 km), and water vapor (3-20 km). The group’s four lidars deployed at TMF and Mauna Loa Observatory, HI (MLO) have been operating for three decades, and contribute to the long-term records of the international Network for the Detection of Atmospheric Composition Change (NDACC). The tropospheric ozone lidar also provides measurements for the new US-based Tropospheric Ozone Lidar Network (TOLNet), and the water vapor Raman lidar is expected to contribute to the new World Meteorological Organization climate-monitoring network GRUAN (GCOS Reference Upper Air Network). As part of the networks’ activities, several large validation campaigns such as MOHAVE-2009 have taken place at TMF and MLO.

In addition to providing long-term time-series, the lidar instruments provide reference observations for validation of the satellite and airborne measurements such as MLS and TES onboard Aura, and more recently OMPS onboard NPP.

 

In Situ Measurements

JPL has several instruments that perform in situ measurements of atmospheric CO2, H2O, CO, CH4 using Tunable Diode Laser Spectrometers from balloons and aircraft such as Global Hawk, ER-2, WB-47 and small UAVs.

 

Radiosondes, Ozonesondes and Frost-Point Hygrometer Sondes

Measurements from MOHAVE campaign
Average of all water vapor profiles measured by CFH and lidar during the Measurements of Humidity in the
Atmosphere and Validation Experiments 2009 campaign.
 

As part of the JPL-TMF Lidar Group observation Program, three different types of balloon-borne instruments are launched from TMF. Vaisala RS92 Pressure-Temperature-Humidity (PTU) radiosondes have been systematically launched since 2005 in support of the water vapor Raman lidar calibration, providing hundreds of temperature and humidity profiles in the lower and middle troposphere. Electro-Chemical Cell (ECC) ozonesondes are also regularly launched for the validation of satellite and airborne measurements and for profile comparison with the lidar measurements. Frost-Point hygrometers (CFH and NOAA-FPH) are also launched during campaigns to validate the lidar measurements in the upper troposphere/lower stratosphere.

 


Laboratory Studies and Modeling

 

Laboratory Studies

Laboratory activities involve the use of state-of-the-art experimental techniques to measure kinetic, photochemical and spectroscopic parameters related to elementary atmospheric processes. Rate coefficients, cross sections and quantum yields are measured using methods such as laser photolysis, discharge-flow and steady-state photolysis combined with high-sensitivity detection methods such as molecular beam mass spectrometry, long-path UV-visible-NIR absorption, diode laser wavelength modulation spectroscopy and laser-induced fluorescence.

Particular importance is placed on processes that play important roles in polar ozone depletion, long-term trends in stratospheric ozone at mid-latitudes, the oxidizing potential of the troposphere, and the formation of oxidants in urban and regional environments.

Quantitative spectroscopy is another key focus of the laboratory studies program. JPL’s Molecular Spectroscopy Team takes measurements of molecules from the microwave through the ultraviolet spectral regions to measure spectroscopic parameters of atmospheric molecules with extremely high precision and accuracy. NASA remote sensing instruments require these parameters for the measurement of atmospheric composition and structure, important for Earth and planetary sciences, astrobiology and astrophysics investigations.

 

Modeling

In this area, computer models of atmospheric processes are developed and used to interpret data from satellite and field measurements, as prognostic tools to help understand long-term changes in climate and composition, and to diagnose elementary processes in atmospheric transport and chemistry.

For tropospheric studies, researchers use three-dimensional chemical transport models that incorporate information about winds derived from weather models. In combination with detailed emission inventories of trace gases, these models have been used to study long-range pollution transport, to determine the effects of biomass burning on global air quality, and to derive budgets of the production and loss of trace gases and estimate their dependence on natural and anthropogenic sources. Many of these studies use global measurements of trace gases from space to constrain model calculations. These models are also used in satellite validation studies, where they provide a platform for comparing ground-based, aircraft, and satellite measurements. Stratospheric modeling efforts use many of the same tools and techniques to understand the dynamical and chemical processes that lead to stratospheric ozone depletion, and to study the budgets of ozone and other trace gases in the important transition region between the troposphere and stratosphere.

At regional and cloud-resolving scales, a fully coupled aerosol-chemistry-meteorology model (WRF-Chem) has been used to simulate the emission, transport, mixing, and chemical transformation of trace gases and aerosol-cloud interactions. Both direct and indirect effects of aerosols are included in the model and are shown to have significant impacts on clouds and precipitation. The model results are compared closely with satellite observations, and researchers at JPL are exploring ways to establish a framework for the application of satellite data to the evaluation and improvement of model parameterizations.