Cooperative Institute for Research in Environmental Sciences

McMurdo Lidar Project: Introduction

An exciting award from NSF’s Office of Polar Programs funded the Chu Research Group to deploy an Fe Boltzmann lidar to McMurdo, Antarctica to measure the middle and upper atmosphere for three years. Dr. Xinzhao Chu and Dr. Chester S. Gardner, along with their colleagues, developed this lidar more than 10 years ago. With it, we made lidar observations from the North Pole to the South Pole.  In particular, we made lidar measurements at the South Pole (90°S) and Rothera (67.5°S) from 1999-2005. Our research group has upgraded this lidar and it has now been deployed to McMurdo (78°S) since November 2010, to complete an observational chain in Antarctica.

Background

The Earth's polar regions are more sensitive to global climate change than the equatorial areas. This makes the polar middle-atmosphere temperature an excellent candidate for monitoring climate change. Consider too that increases in CH₄ concentrations result in more water vapor content in the middle atmosphere. Combine CO₂ cooling and CH₄ chemistry, and the result is enhanced conditions for the formation of polar mesospheric clouds (PMC). Thus, these clouds may provide an early indication of climate change.

Though polar middle-atmosphere data are vital to better understanding global climate change, the remote and harsh environment makes collecting reliable data a signficant challenge. That's why we developed the Fe (iron) Boltzmann temperature lidar -- an advanced remote sensing instrument. This sophisticated lidar is capable of full-diurnal-cycle measurements of temperature from 30-110 km, and detection of both mesospheric and stratospheric clouds. It measures mesospheric Fe density for both day and night throughout an entire year. By analyzing temperature or density perturbations, we can derive gravity wave potential energy density with this lidar data.

Pole-to-Pole Journey of the Fe Boltzmann Lidar

The Amundsen-Scott South Pole Station from 1999 to 2001

We deployed this lidar several times in the past:

• to the North Pole and Arctic on board the NSF/NCAR Electra aircraft in 1999,
• to the Amundsen-Scott South Pole Station in 1999-2001,
• and to Rothera Station, Antarctica in 2002-2005.

Extensive datasets and significant scientific results on atmospheric temperatures, polar mesospheric clouds, mesospheric Fe density, and gravity waves have been obtained at the South Pole (90°S) and Rothera (67.5°S) with this lidar. Read more about the Past Deployments of this lidar.

Current Research Goals

LIDAR stations in Antarctica

Although the data gathered between 1999 and 2005 highlighted signficant scientific discoveries, there is a critical data gap in latitude between 90°S and 69°S, especially for range-resolved temperatures and polar mesospheric clouds. While the polar middle-atmosphere is sensitive to climate change, a long-term year-round temperature record has never been obtained in Antarctica – a contrast to the Arctic region. Information about gravity wave properties and large-scale dynamics is lacking in the Antarctic region.

We are at the McMurdo Station (78°S, 167°E), mid-way between the South Pole and Antarctic Circle, conducting multi-year lidar observations of polar middle atmosphere to address the following scientific problems:

1. Measure atmospheric temperature profiles from sea level to 110 km with year-round (0-110 km) and full-diurnal (30-110 km) coverage for both day and night. These data will be used for monitoring climate change and to validate general circulation models for better understanding of the Earth’s climate at high southern latitudes.
2. Measure polar mesospheric clouds (80-87 km) and mesospheric Fe layers (75-115 km) through the entire summer season to characterize PMC morphology, heterogeneous chemistry, and dynamic processes in the summer mesosphere and lower thermosphere.
3. Make year-round measurements of the mesospheric Fe layers for comparison with a sophisticated gas-phase Leeds mesospheric chemistry model.
4. By analyzing temperature and atmospheric density perturbations, we will characterize gravity wave potential energy density and investigate wave coupling from lower to middle atmosphere.
5. Through collaborations with polar researchers, we will help fill an important gap in the latitudinal coverage of year-round range-resolved measurements in Antarctica, clearly define the latitudinal trends in temperature and PMC, and quantify the inter-hemispheric differences in the climate of the MLT region.

Long-term project merits

Our long-term goal is to operate the lidar at McMurdo for a complete solar cycle (11 years) to characterize middle atmosphere responses to the solar cycle, annual and inter-annual variations and to extract long-term secular trends to assess climate change in the middle atmosphere.