SGP/MERGESONDE/C1 - Inconsistencies at day boundaries.

Please be aware that there are often inconsistencies at the boundaries between UTC days. 
The severity is dependent on the data variable and the number of sonde launches per day. 
Relative humidity, dew point, wind speed and wind direction are most affected. 

The contribution from sonde data is highest near the sonde times, then decreasing 
strongly. (Example of sonde 
contribution to value at 1 km height: )

Relative humidity at NSA can have large discontinuities at the UTC date boundaries due to 
only having two sonde launches per day. When weather or instrument malfunction reduce the 
number of launches the discontinuity can increase. (Example  at SGP at 1 km and Example at NSA at 1km )

Wind speed Example  at 1 km 
height: 

Temperature values are not affected as severely as other variables (Example  at NSA and Example at SGP 1 km height.)

A new version of mergesonde is in progress. The interpolatedsonde VAP, which produces 

a daily file of thermodynamic variables from radiosonde soundings only (without merging 
with ECMWF data) may be an option, depending upon application.

• rh
• precip
• vapor_source
• wspd
• sh
• rh_scaled
• height
• v_wind
• sonde_fraction_rh
• sonde_fraction
• temp
• bar_pres
• vap_pres
• potential_temp
• u_wind
• wdir
• dp