Convection and Precipitation /Electrification (CaPE) experiment

The CaPE experiment was conducted over east central Florida near Cape Canaveral in 1991. NASA provided aircraft remote sensing instrumentation to observe convection and related parameters (e.g., water vapor, precipitation, lightning). One of the NASA instruments participating was the Multispectral Atmospheric Mapping Sensor (MAMS). A primary objective for MAMS was measuring moisture variations associated with the sea-breeze front and to do this, if possible, in conjunction with the King Air aircraft from the National Center for Atmospheric Research (NCAR) and the University of Wyoming. These aircraft provide high temporal and spatial resolution in situ measurements of moisture, temperature, winds, etc., which can be used as ground truth for the remote sensing instrumentation. In addition to the King Air aircraft, ground truth data is available from CLASS (Cross-chain Loran Atmospheric Sounding System) rawinsondes launched during the experiment. Conventional surface observations are available from numerous Portable Automated Mesonet (PAM) sites located within the experiment domain. In addition to wind observations from the PAM stations, wind measurements are also available from the Kennedy Space Center (KSC) wind tower network.

On 6 August MAMS, along with other sensors, was flown aboard a NASA high-altitude (~20 km) ER-2 aircraft. The instrument provides imagery in 12 channels in the visible, near-infrared and infrared region of the electromagnetic spectrum at 100 m nadir resolution. The so-called split-window channels (11 and 12 µm) of MAMS can be used to derive precipitable water (PW) with high precision using an approach called the physical split window (PSW) technique. By using MAMS split-window data from the 6 August 1991 case, insight into meso-gamma scale water vapor features associated with the sea breeze can be gained. The moisture patterns of a moderate sea breeze, which occurred on 6 August 1991 over east central Florida, was examined using multispectral infrared data, King Air aircraft in situ data, and surface PAM site data. The PSW technique was successfully applied to the multispectral data available from MAMS. The MAMS PW retrievals were able to delineate the sea breeze front was well as a modest gradient behind it.

A composite of MAMS visible images (about 1700-1730 UTC) with PW (mm) contours superimposed for 6 August 1991 over the Cape Canaveral region of east central Florida is shown in the Figure on the right.The sea-breeze front is marked by the northwest to southeast oriented line of cumulus clouds. The sea-breeze developed along the Florida coastline and propagated inland throughout the day. Isolated thunderstorms developed in late afternoon along the cloud line at the leading edge of the front. PW retrievals were made with data from the MAMS infrared channels using the Physical Split Window (PSW) technique. The analysis depicts a moisture maximum of ~40-44 mm along the front, with a somewhat drier region behind it and a relatively moist environment ahead of it. The southernmost flight leg is perpendicular to the coast shows a subtle but significant gradient (~4 mm/10 km) just behind the front. A weaker gradient is present over the Merritt Island/Indian river region. Confirmation of many of the PW features shown by MAMS was provided by the University of Wyoming King Air aircraft flying along the lowest MAMS flight leg approximately one hour after the MAMS data were collected.

MAMS Flights during CaPE

The date links refer to data quality for that date.

|| Back to Aircraft Page || Back to Infrared Group Homepage || Back to GHCC Homepage ||

Responsible Official: Dr. James L. Smoot (James.L.Smoot@nasa.gov)
Page Curator: Paul J. Meyer (paul.meyer@msfc.nasa.gov)

Last updated on: May 30, 1997