The TC4 mission was supported by the Atmospheric Composition research area of NASA's Earth Science Division. We thank the aircraft managers, engineers, and ground crews of all the aircraft that participated in TC4. We particularly thank the pilots of the ER-2, David Wright, Denis Steele, and DeLewis Porter, and Mobile Pilot Jan Nystrom, the WB-57F pilots Rob Rivers, Scott Reagan, and William Rieke, and Backseaters, John Bain, Dominic Del Russo, and Joseph Gerky, and the DC-8 pilots William Brocket, Mike Fuller, Manny Puerta, and the late Edwin Lewis. The ER-2 aircraft and pilots were very well supported by the personnel of NASA's Dryden Flight Research Center Airborne Science Directorate, the WB-57F by NASA's Johnson Space Center High Altitude Research Program, and the DC-8 by the University of North Dakota's National Science Education Research Center. We thank the ER-2 Aircraft Program Director, Robert Curry, the DC-8 Program Director, Rick Shetter, and the WB-57F Program Manager, Ken Cockrell. We also thank the ER-2 aircraft coordinators Jacques Vachon and Mike Kapitzke, the DC-8 Aircraft Manager Steve Davis and the DC-8 Mission Manager Dave Easmunt, and the WB-57F Program Engineers Shelly Baccus and Frank Caldeiro, the Mission Manager William (Bud) Meins, and the Integration Manager Marty Ross, as well as all of the aircraft crews. The NASA Ames Earth Science Project Office made tremendous contributions to the operations and overall success of TC4. Our special thanks go to Kent Schiffer, Mike Gaunce, Sue Tolley, Quincy Allison, Dan Chirica, and the late Steve Gaines. We also appreciate the support of the NPOL radar, NATIVE trailer, and Sat Com groups in Panama and the SMART mobile radar in Costa Rica. We thank the RTMM and REVEAL teams from NASA Marshall Earth Science Office and NASA Dryden Test Systems Directorate, respectively, for enabling the collection and display of airborne and ground-based data sets, which supported mission planning and enabled critical real-time decision making. The shipment of the tons of science hardware to San Jose, Costa Rica, could not have been accomplished without the tremendous efforts of the U.S. Air Force Material Command. We would also like to thank the pilots and staff of the NASA C-9, NASA G-3, and Beale Air force Base KC-135 for all their support. We would like to record our special appreciation of and thanks to Kathy Thompson for her dedication and effort throughout the planning, operation, and postmission analysis of TC4. Kathy was ably assisted by Rose Kendall, to whom we also send our thanks. Tommy Thompson's myriad skills were critical to the successful operation of the mission in the field. We thank him for being there to make sure, once again, that it all worked. The airport personnel at Juan Santamaria airport were very helpful to the mission. The various Costa Rican government, academic, and commercial organizations we worked with, including CeNAT, DGAC, Alterra, ICE, IMN, ADS, and the Servicio de Vigilancia Aerea, were invaluable. The same can be said for the Panamanian government and academic organizations. The Costa Rican National Center for Advanced Technology (CENAT), and especially Oliver Gómez, were instrumental in logistical support, both before and during the mission. The meteorological forecasting team in Costa Rica was critical to the success of TC4. This was a joint effort of the Instituto Meteorológico Nacional (IMN), the Centro de Investigaciones Geofisicas (CIGEFI) at the University of Costa Rica, and the Instituto Costarricense de Electricidad (ICE). IMN team members were Evelyn Quirós Badilla, Gustavo Murillo Zumbado, and Eladio Solano León; the CIGEFI group, under the direction of Jorge Amador, included Erick Rivera Fernández, Marcela Ulate Medrano, Ana María Duran Quesada, and Blanca Calderón Solera, and Berny Fallas López represented ICE. NASA Headquarters management and program managers supported this mission in many meaningful ways. The U.S. Embassies in Costa Rica and Panama were especially helpful in coordinating this effort. We appreciate the hospitality of Costa Rican Ambassador Mark Langdale. We appreciate the help of the people of Panama who facilitated the use of the NATIVE trailer and the NPOL radar, and the people of the Galapagos who helped with balloon launching. We especially thank the President and people of Costa Rica, who reconstructed the hangar used by the WB-57F, loaned us the President's hangar for the ER-2, and were very friendly, helpful, and hospitable.