Interagency Field Campaigns Converge at the Southern Great Plains Site

Published: 18 April 2011

Once again joining forces with colleagues from NASA, several field campaigns are converging at the ARM Southern Great Plains (SGP) site in Oklahoma this spring. These campaigns involve intensive efforts to obtain measurements about cloud properties that will help scientists improve computer models that forecast weather and climate. Compared to previous campaigns of a similar nature, these data sets will be significantly more detailed due the addition of new and upgraded instruments installed at the SGP site in the past year through funding from the American Recovery and Reinvestment Act of 2009.

This simplified graphic illustrates the measurement strategy for MC3E, involving both aircraft and comprehensive surface measurements throughout the study domain.
Midlatitude Continental Convective Clouds Experiment (MC3E). Beginning on Earth Day, April 22, this campaign will obtain comprehensive measurements of storm clouds from the ground and sky. As described in this Brookhaven National Laboratory news release, it takes full advantage of new ARM instrumentation—particularly new precipitation radars—installed throughout the SGP site, supplemented by additional radars, precipitation instrumentation, a weather balloon network, and aircraft measurements provided by NASA. Their goal is to provide the most complete characterization data set for convective cloud systems, precipitation, and their environment that has ever been obtained, providing details about cumulus clouds that have never before been available for weather and climate models.

Five additional campaigns are being conducted in conjunction with this month-long campaign; to find out more, visit the MC3E web page.

Middle Latitude Airborne Cirrus Properties Experiment or (MACPEX). In the MACPEX campaign, which began in March, a heavily instrumented NASA WB-57 research aircraft is flying high over the SGP site in coordination with A-Train satellite overpasses to obtain measurements of cirrus cloud properties, like ice crystal sizes and shapes. Scientists will use the combined measurements to study the impact of cirrus clouds on energy entering and leaving the Earth, as well as to validate satellite data acquisition techniques.

In conjunction with MACPEX, a Learjet research aircraft from Stratton Park Engineering Inc., is obtaining measurements in the cirrus clouds and thunderstorm anvil outflow. These flights, lasting through the end of April, will add significantly to the Small Particles in Cirrus (SPARTICUS) campaign data set, collected a year ago.

The Learjet research payload includes new versions of two probes used during the original campaign—a fast forward scattering probe and fast cloud droplet probe. The “fast” versions of these probes, provided through the ARM Aerial Facility, incorporate an upgraded design and electronics to minimize the effects of “forwarded scattering,” or shattering of ice crystals, that scientists believe may be causing erroneous measurements.

Key ground-based measurements from the SGP site will come from cloud radars, cloud and aerosol lidars, an atmospheric emitted radiance interferometer, and infrared thermometers. Measurements obtained during MACPEX and SPARTICUS will help scientists resolve discrepancies and improve the methodology for acquiring cirrus data, leading to overall improvements in climate model accuracy.