Weather Balloon (Rawinsonde) Information

Availability:  Rawinsonde (pronounced ray-win-sond) weather balloons are NOT routinely launched at Edwards AFB.   They are only launched when officially scheduled in support of a test mission.   (Edwards AFB is not a part of the national rawinsonde network which is operated by the National Weather Service.)   Only the most recent rawinsonde launched at Edwards AFB is posted on this page.   Please check the date and time before using the data available on this page.

Scheduling: Rawinsondes MUST be scheduled via the Edwards AFB Center Scheduling Enterprise (CSE) process by test organization scheduling personnel.   A fully reimbursable Job Order Number (JON), not an overhead JON, MUST be provided on the schedule.   Commercial customers with a pre-established test program and a funded JON but no base scheduling personnel should contact the 412 OSS scheduling office or their Test Management Group POC to schedule a rawinsonde.   The Edwards AFB Weather Station cannot accept a rawinsonde launch request other than via CSE.   Launch requests must be scheduled at least 24 hours in advance.   Organizations that have access to CSE and can see a rawinsonde scheduled by another organization are encouraged to schedule their own launch to ensure required data is collected.   It is common for test missions to delay or cancel which also cancels the associated balloon.   Test programs not pre-established with the Edwards AFB Test Management Group must contact the 412 Test Wing Initial Point of Contact office.

Time Considerations:  Approximately one hour is required to prepare for a rawinsonde launch.   Weather personnel verify mission status via the Current Operations office prior to preparing for launch.   Once the mission is verified and the packaging seals on expendables are broken, the balloon will be launched and the customer charged even if the mission subsequently cancels.   Upon launch, the balloon typically ascends at 1,000 feet per minute.   Therefore, if a customer requires balloon data to 60,000 feet, it will take approximately one hour to reach that altitude.   Post-processing and data dissemination require approximately 15-20 minutes.   Data is posted to this web site and transferred to the Time Space Positioning Information office.   All rawinsondes are tracked until balloon burst no matter what altitude the customer requires, time permitting.   Intermediate processing and dissemination (e.g. Data to 10 KFT needed ASAP) is available and should be noted in the Remarks section of the CSE request.

Launch Limitations:  Balloons will not be launched when the sustained winds equal or exceed 20 knots or when lightning is within 25 nautical miles of the launch facility.   Weekend launches are difficult to support and require 72 hours prior coordination and a contact phone number to verify status prior to launch.   In the event that contact cannot be established, the balloon will be launched as scheduled and the customer charged.

Data Provided:  Rawinsonde balloons launched from Edwards AFB carry an instrument package called a radiosonde.   Due to the fact that the radiosonde is tracked and provides wind information, the combination is called a rawinsonde.  The radiosonde instrument transmits temperature, humidity and three-dimensional GPS postition information to the ground station once per second.  This is combined with a pre-launch surface weather observation (temperature, relative humidity, pressure and winds) and data from a ground-based GPS receiver.   The ground-based GPS receiver has been surveyed by the National Geospatial-Intelligence Agency thus allowing accurate differential GPS correction of the airborne GPS data.  By knowing the measured temperature and relative humidity plus the change in altitude every second, the pressure at each level is derived. These three (temperature, relative humidity and pressure) basic thermodynamic values are then used to derive the other parameters (dew point, density, absolute humidity, velocity of sound, index of refraction and vapor pressure) available from this service. The GPS position data is also used to compute the wind direction (referenced to true north) and speed.