All of the aerosol data submitted has been corrected to Standard Temperature and Pressure (STP),
with the exception of absorption,  scattering, FSSP and liquid water content (LWC).  See table 1) below
for a complete list of submitted variables and whether they have been STP corrected or not.
This correction to STP was done for two main reasons:
(1) Most gas phase measurements have been submitted as mixing ratios (similar to STP correction)
(2) Our instruments are measuring at pressures and temperatures different from ambient conditions
(due to RAM pressure increase and sampling at aircraft cabin temperature).

The correction was applied using the formula:
             STP data = instrument data*(Standard P/Sample P)*(Sample T/Standard T)
                        with Standard P=1013 mb and Standard T=298.15 K

This data can then be corrected to ambient conditions using the ambient P and T and the following
formula:
             Ambient data = STP data*(Ambient P/Standard P)*(Standard T/Ambient T)
                        with Ambient P and T found in the aircraft data files and merged data sets

The optical data (absorption and scattering) have not been corrected to STP for historical reasons.
Most uses of aerosol optical data (visibility, radiative forcing, and comparison to remotely
measured aerosol properties for example) have required ambient aerosol optical properties,
not STP corrected data.  The optical data submitted is not truly at ambient conditions (see (2)
above). To retrieve true ambient optical properties, data must be corrected to ambient P, T and
Relative Humidity (RH) conditions. We have included  P, T and RH columns in our submitted data.

The liquid water content (LWC) of the air and FSSP-300 data are also not corrected to STP.
LWC is provided by the Gerber Probe (PVM) for significant cloud and for all droplet sizes in gm/m3.
LWC can also be determined from integral FSSP-300 for sizes up to 20um [units of um3/cm3] (multiply 
          by 10^-6 to get gm/m3).  Low values in the FSSP-300 generally reflect aerosol volume while higher
          values (at high relative humidity) are generally cloud LWC. Because the FSSP-300 has an upper 
          limit of 20um these LWC values will often be less than Gerber probe (PVM) LWC.

Table 1):

Measurement:                                 STP correction:              Submitted data found in:

----------------------------------------------------------------------------------------
CN @ 300 C                                             Yes                    tcaerp##.trp
CN @ 30 C                                              Yes                    tcaerp##.trp
LWC                                                    No                     tcaerp##.trp
----------------------------------------------------------------------------------------
Combined DMA and OPC integral number @ 50 C
 (particle diameter range 0.007 um<=Dp<=20.0 um)       Yes                    tcszap##.trp
Total DMA number @ 50 C (0.007 um<=Dp<=0.1 um)         Yes                    tcszap##.trp
Total OPC number @ 50 C (0.1 um<=Dp<=20.0 um)          Yes                    tcszap##.trp
OPC integral number @ 50 C (0.1 um<=Dp<=0.75 um)       Yes                    tcszap##.trp
OPC integral number @ 50 C (0.75 um<=Dp<=20.0 um)      Yes                    tcszap##.trp
Same as above for integral surface area concentration  Yes                    tcszap##.trp
Same as above for particles integral volume            Yes                    tcszap##.trp
-----------------------------------------------------------------------------------------
Total scattering @450nm, 550nm and 700nm               No                     tcoptp##.trp
Backscattering @450nm, 550nm and 700nm                 No                     tcoptp##.trp
Submicron scattering @450nm, 550nm and 700nm           No                     tcoptp##.trp
Submicron backscattering @450nm, 550nm and 700nm       No                     tcoptp##.trp
Angstrom coefficient using 450-700 wavelengths         No                     tcoptp##.trp
Angstrom coefficient using 450-550 wavelengths         No                     tcoptp##.trp
Absorption @565nm total                                No                     tcoptp##.trp
Absorption @565nm submicron                            No                     tcoptp##.trp
------------------------------------------------------------------------------------------
FSSP integral number, 0.3 um <=Dp<= 1.0 um             No                     tcfssp##.trp
FSSP integral number, 1.0 um <=Dp<= 20.0 um            No                     tcfssp##.trp
FSSP integral number, 0.3 um <=Dp<= 20.0 um            No                     tcfssp##.trp
Same as above for FSSP integral surface area           No                     tcfssp##.trp
Same as above for FSSP integral volume                 No                     tcfssp##.trp
-------------------------------------------------------------------------------------------
APS integral number, 0.7 um <=Dp<= 20.0 um             Yes                    tcapsp##.trp
APS integral surface area, 0.7 um <=Dp<= 20.0 um       Yes                    tcapsp##.trp
APS integral volume, 0.7 um <=Dp<= 20.0 um             Yes                    tcapsp##.trp
-------------------------------------------------------------------------------------------
CN = Condensation nuclei concentrations
LWC = Liquid water content
DMA = Differential mobility analyzer (size distribution measurement with 0.007 um<=diameter<=0.1 um)
OPC = Optical particle counter (size distribution measurement with 0.1 um<=diam<=0.75 um
      and 0.75 um<=diam<=20.0 um cut sizes)
FSSP = Forward Scattering Spectrometer Probe FSSP-300
APS = Aerosol Particle Sizer, TSI Inc., measures aerodynamic diameters using a density of 1.0 g/cc