Department of Civil & Environmental Engineering

Laboratory for Atmospheric Research

Remote Sensing

Since the late 1990s, LAR has been engaged in several projects related to remote sensing. These projects cover a wide range of remote-sensing applications such as ground-based validation of satellite instruments and retrievals of atmospheric trace gases and cloud properties. Remote sensing fieldwork has been conducted around the globe, from the Pacific Northwest to the polar regions. LAR personnel are also developing remote sensing instrumentation across various spectral bands, including the ultra-violet, visible and infrared.

ICECAPS

ICECAPS

An accurate assessment of clouds and the energy budget over Greenland are important factors for consideration in climate modeling and for increasing understanding of the region's changing climate. In 2010, the Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit (ICECAPS) experiment began at at the top of the Greenland Ice Sheet. ICECAPS has deployed a comprehensive suite of cloud-atmosphere observing instruments, including microwave and infrared spectrometers, cloud radar, depolarization lidar, ceilometer, precipitation sensor, sodar, and a twice-daily radiosonde program. Measurements from this instrument suite are being used to derive critical baseline atmospheric data, including atmospheric state (tropospheric temperature, moisture, and wind profiles), macrophysical and microphysical properties of clouds (occurrence, vertical boundaries, temperature, phase, water content, and characteristic particle size), and precipitation (type and rate). When combined with ongoing measurements at Summit, these data can be used to study processes that impact the surface energy budget and precipitation over Greenland, as well as to address questions related to atmospheric stability, cloud phase composition, the persistence of stratiform clouds, and aerosol-cloud interactions.



Arctic observation site
Arctic Observation Site

MF-DOAS

MF-DOAS

A MultiFunction Differential Optical Absorption Spectroscopy (MF-DOAS) instrument was developed by LAR researchers for ground-based validation of the Aura Satellite/Ozone Monitoring Instrument (OMI) and for measurement of urban air pollution. The MF-DOAS instrument is unique in its ability to take both scattered sky measurements and direct sun measurements. This combination allows measurement of air pollution with simple stratospheric air mass factors from the direct sun and also makes use of the MAX-DOAS azimuth/elevation technique coupled with a spherical radiative transfer code to derive spatial and full day temporal dependence of urban pollutants. The tropospheric NO2 pollution trends are captured by the MF-DOAS instrument as confirmed by in-situ measurements. Overall, the tropospheric spatial variation of NO2 from MF-DOAS and OMI correlate well.

MF-DOAS
MF-DOAS instrument

AAIRO

AAIRO

To fully understand the Arctic system, it is imperative that atmospheric measurements of the lower atmosphere be made across the Arctic, including over the Arctic Ocean. Currently, high-quality observations are being made at three Intensive Observing Sites (Barrow, Eureka, and Summit), which are all on land. Automated weather stations are frequently deployed on ocean and ice buoys, but they only sample surface conditions. In many cases, passive satellite instruments are only able to measure down to the tops of clouds, but are unable to profile the atmospheric conditions between the surface and the cloud base. Thus, LAR is developing new instruments platforms to fill this gap in the Arctic Observing Network so that pressing questions about rapid Arctic change can be addressed.

Cloud cover over Greenland

Polar Clouds

Polar Clouds

This research is focused on characterizing the interactions between the atmospheric state, cloud properties, radiation, and precipitation at Summit, Greenland. The objective is to investigate a number of important cloud-related processes, how these interact with the Arctic climate system, and their impact on the surface energy and mass budgets. These include:

  1. Low-cloud persistence mechanisms that lead to long-lived Arctic stratiform clouds, which interact strongly with the atmospheric structure and surface energy budget;
  2. Cloud-phase partitioning, which determines the cloud microphysical composition and, ultimately, the effects that clouds have on atmospheric radiation and the hydrologic cycle; and
  3. Precipitation partitioning, in order to understand the different modes of precipitation at Summit and how these impact the total surface accumulation.

To address these important topics, this project utilizes detailed observations from an advanced suite of ground-based remote sensors deployed at Summit as part of the ICECAPS project in combination with data from satellite-borne active remote sensors. High-resolution numerical modeling is being used to investigate many of the fine-scale cloud processes and their mesoscale influences. These studies are also considering how similar measurements and model studies made at other Arctic locations compare to those made at Summit, Greenland.

Polar temperature modeling
Civil & Environmental Engineering, PO Box 642910, Washington State University, Pullman WA 99164-2910, 509-335-2576