SGP/EBBR/E4 - Reprocess: Soil Moisture Probe Low at Times

On 18 June 1996, soil moisture probe 5 data reduced to a very low level.  
At 0000 GMT on 19 June 1996 the soil moisture indicated below zero, which 
is not physically possible.  Over the next few months the soil dried to a 
low enough moisture level that the output again went too low.  The qc 
minimum limit of 0 will indicate these times.  The output recovered to 
reasonable values on 1 July at 2100 GMT.  It again went low on 4 
July at 0100 and remained that way until at least 8 July.  No data is 
available from 9 July to 24 July to allow us to see the behavior during 
that period.  On 27 July, at 0330 GMT, the output was very high (113.8) for 
some unknown reason.  The output also went offscale at 0000 on 3 August, 
for an unknown reason.  The output again went low at 0800-1530 GMT on 10 
September and 0000 GMT on 11 September through 0900 GMT on 15 September.  No 
incorrect values have occurred since.  However, it is clear that at very 
low soil moisture, probe 5 indicates lower than normal.  It will be replaced 
when a spare is available.  

Affected data are:

15 minute: r_sm5

30 minute: sm5, c_shf5, g5, cs5, ces5, ave_shf, e, h

Recalculation of soil heat flux, and latent and sensible heat fluxes may 
be performed using the other four sets of soil probes, as below:

ave_shf = (g1 + g2 + g3 + g4)/4

e = -(q + ave_shf)/(1 + bowen)

h = -(e + ave_shf + q)

• Soil heat capacity 5(soil_heat_capacity_5)
• Soil heat flow 5, corrected for soil moisture(corr_soil_heat_flow_5)
• Change in energy storage 5, 0-5 cm soil layer(energy_storage_change_5)
• Soil moisture 5, gravimetric(soil_moisture_5)
• Surface latent heat flux(latent_heat_flux)
• Surface soil heat flux, average of fluxes 1-5(surface_soil_heat_flux_avg)
• Surface soil heat flux 5(surface_soil_heat_flux_5)
• Surface sensible heat flux(sensible_heat_flux)

• Soil moisture 5 (resistance)(soil_moisture_5_r)