Engineering topics
Publications and source records attributed to Wheeler, Mark M..
This paper describes the new wet microburst forecasting and detection efforts developed to support ground and launch operations at Kennedy Space Center (KSC) and the Cape Canaveral Air Station (CCAS).
This report documents fog precursors and fog climatology at Kennedy Space Center (KSC) Florida from 1986 to 1990. The major emphasis of this report focuses on rapidly developing fog events that would affect the less than 7-statute mile visibility rule for End-Of-Mission (EOM) Shuttle landing at KSC (Rule 4-64(A)). The Applied Meteorology Unit's (AMU's) work is to: develop a data base for study of fog associated weather conditions relating to violations of this landing constraint; develop forecast techniques or rules-of-thumb to determine whether or not current conditions are likely to result in an acceptable condition at landing; validate the forecast techniques; and transition techniques to operational use. As part of the analysis the fog events were categorized as either advection, pre-frontal or radiation. As a result of these analyses, the AMU developed a fog climatological data base, identified fog precursors and developed forecaster tools and decision trees. The fog climatological analysis indicates that during the fog season (October to April) there is a higher risk for a visibility violation at KSC during the early morning hours (0700 to 1200 UTC), while 95 percent of all fog events have dissipated by 1600 UTC. A high number of fog events are characterized by a westerly component to the surface wind at KSC (92 percent) and 83 percent of the fog events had fog develop west of KSC first (up to 2 hours). The AMU developed fog decision trees and forecaster tools that would help the forecaster identify fog precursors up to 12 hours in advance. Using the decision trees as process tools ensures the important meteorological data are not overlooked in the forecast process. With these tools and a better understanding of fog formation in the local KSC area, the Shuttle weather support forecaster should be able to give the Launch and Flight Directors a better KSC fog forecast with more confidence.
The purpose of this report is to document the Applied Meteorology Unit's implementation and evaluation of the wind algorithm developed by Marshall Space Flight Center (MSFC) on the data analysis processor (DAP) of NASA's 50 MHz doppler radar wind profiler (DRWP). The report also includes a summary of the 50 MHz DRWP characteristics and performance and a proposed concept of operations for the DRWP.
Space Shuttle landings at Kennedy Space Center (KSC) are of special concern to NASA's landing community because of Florida's rapidly changing weather conditions. Since a large number of Shuttle landing attempts occur in the morning hours (just after sunrise) fog and stratus development are a problem. The deorbit burn decision for a landing at KSC is typically made 90 minutes before Shuttle touchdown. In that 90 minutes weather conditions can change very rapidly. Fog to the west of KSC an advect in and reduce visibility to less than 7 miles. The most important difference between Shuttle and normal aircraft landings is that the Shuttle has no go-around capability requiring a forecast with little room for error. To help guard against rapidly changing weather conditions, flight rules have been developed as guidelines for all landings. This paper concerns fog development that would affect less than 7-statue mile visibility rule which is in effect for End-Of-Mission (EOM) Shuttle landings at KSC (Rule 4-64(A)). Data used for this analysis included hourly surface observations at the X68 Shuttle Landing Facility (SLF) and upper-air observations form the CCAFS (Cape Canaveral Air Force Station-72794) rawinsonde site for the five year period, 1986 to 1990. This investigation focused on rapidly developing fog or stratus that developed between decision time and landing.
Weather conditions are documented prior to and during the STS-48 attempted landing at the Shuttle Landing Facility at KSC on 18 Sep. 1991. Trends in meteorological data during 17 and 18 Sep. are examined along with their relationship to the overall weather pattern observed over the KSC region. The primary weather problems during the landing were the formation of showers within 10 nautical miles of the SLF and any ceiling less than 10,000 ft. The controlling factor of the weather was a high pressure ridge that was gradually weakening and moving off the northeast. As this occurred, the low level flow was switching from a easterly to a southeasterly direction. This change in wind direction was reflected by shower movement on the McGill radar and by trends in rawinsondes launched from the Cape. These rawinsondes also indicated that the boundary layers was becoming slightly more unstable several hours prior to the attempted landing which may have aided in the development of clouds and small isolated showers. Also, analyses of Doppler wind profiler and rawinsondes indicated a possible midlevel disturbance in the easterly flow pattern near 700 mb. This weak disturbance may have made the atmosphere a little more unstable early on 18 Sep. Finally, embedded within the southeasterly flow were several bands of low clouds. These clouds were rather difficult to see in unenhanced IR satellite imagery available to forecasters in real time. However, post analyses using several different enhancement curves, adapted from NESDIS, clearly reveals the presence of these clouds.