1. J. Vorrath OC3570 Presentations Summer 2003
Atmospheric Moisture Content Near the Sea Surface Using Vaisala Rawinsondes
J. Vorrath
OC3570 Presentations
Summer 2003

2. Purpose
To use Vaisala rawinsondes to closely examine the moisture content of the lowest levels of the atmosphere.

3. Fundamental Issues and Importance for Navy
Our interest in the answer to this question comes from a desire to know more about the structure of the lowest level of the atmospheric planetary boundary layer, specifically the moisture content. This could impact evaporation duct analysis and, depending on the performance of the sensor, impact the confidence level of Vaisala rawinsonde users.

4. Fundamental Issues and Importance for Navy

5. Method
High-tech adaptation of Vaisala rawinsonde for use with an extendable artificial appendage (a.k.a. the duct tape sensor to stick method).
Take measurements that alternate between approximately 3 meters in height and as near to the sea surface as possible.

6. Method

7. A. B.

9. A. B.

11. A. B.

13. B. A.

15. Results
Sensing the nearly saturated air above the sea surface is only possible beneath a height of 0.5 meters (preferably even lower).
Moisture content of the atmosphere does follow the theoretical profiles.
Don’t believe the hype, Vaisala pressure sensors may have some sort of lag time.

16. Recommendations Use the RHIB (no matter what the engineer says).
How about a “rawinsonde-on-small-styrofoam-float-method” (a.k.a. the Vorrath Low Level Moisture-O-Meter)?
Coordination of chronometers is key.
Use longer “up” and “down” intervals.

17. Referencess Frederickson, P., June 1998-September 2000. Matlab code.
Guest, P., August – September MATLAB code and topic discussion.
Jordan, M., October Matlab code.
Vaisala company home page.