Troposphere 

There are a few instruments that measure tropospheric conditions.

Early in the record, there are instruments on kites.

Rocket sondes were used from a limited number of sites in 1960's to 1970's
  https://www.aparc-climate.org/data-centre/data-access/rocketsonde/

Pibal is a pilot balloon that may have a light for night-time tracking.  Tracking
is done optically by a theodolite to determine wind speeds as a function of height.
Thermal wind gives temperature information.

Atmospheric Motion Vectors (AMV): AMV are considered to be low quality observations
because clouds don't travel with the the ambiant flow, and there is lack of precision in 
the height of hte cloud.  So the AMV are given relatively low weight by the DA.

Sondes are a major source of tropospheric temperature, winds and humidity. Modern
radiosondes can reach 3 hPa.  

Aircraft data is currently the largest source of tropospheric observations (by size).
Most aircraft only make wind and temperature measurements and not humidity measurements.
Aircraft data can have high resoluiton along the flight path.


                                    Not Used

VADWND: Doppler Radar gets wind speed from clear air reflections off dust, insects and 
even birds. Assuming a constant descent rate, a velocity can be determined.  Used in 
the operational GFS but not in CORe.

Vertical Profilers.

Radar doppler winds

Satellite data for surface wind speeds, atmospheric temperatures, humidity and winds.

Cloud information aside from AMV.

Dust, ozone or other chemical obsevations.