Tag
Variable
Remarks
100
Time
The T-28 data system is set to UTC, and recorded in a 24-hour format for STEPS. It is set daily within a second of WWV, but suffers loss of a second or two each time system is booted.
101
Dynamic Pressure 1
102
Dynamic Pressure 2
Both dynamic pressures are read from the same pitot tube line (with the inlet out on the right wing) using two different but nearly identical sensors. [hPa]
103
Static Pressure 1
104
Static Pressure 2
Both static pressures are read from the same static pressure line (inlet on the rear fuselage) using two different but nearly identical sensors. [hPa]
105
Rate of Climb
Not usable during STEPS.
106
Rosemount Temperature
Computed from the reading of a standard, deiced, Rosemount aircraft total air temperature probe. It commonly suffers from wetting and reads low in clouds. [°C]
107
Reverse Flow Temperature
This is static temperature is computed from the reading of a platinum resistance element placed inside a custom-design "reverse-flow" housing. It normally does not get wet in clouds or in regions of high precipitation water concentration. Ice may sometimes build up to such an extent on the housing that airflow is changed and temperature readings are affected even though the sensor is not wetted. Its response to changes in angle of attack is greater than that of the Rosemount probe. [°C]
108
Manifold Pressure
Pressure inside the engine manifold (an indicator of power being developed by the engine) is recorded from a standard aircraft engine pressure sensor. [inches of mercury]
109
Acceleration
Vertical acceleration is determined by a Humphrey gyro-stabilized accelerometer. [g's]
110
Pitch
The accelerometer also gives angle of the fuselage relative to horizontal (positive for nose up). [deg]
111
Roll
The accelerometer also gives angle of the wings relative to horizontal. Angle is positive for a left bank (left wing down). [deg]
116
Voltage Regulator
Voltage of power source for some instruments. [volts]
118
NCAR True Airspeed
Airspeed computed by an analog circuit; can be used to clock PMS OAP-2D probes. Less accurate than "Calculated TAS", Tag 211
119
PMS End Element 1
Voltage readings of PMS OAP-2D probe end diodes. Used to monitor for fogging and icing of probe.
120
PMS End Element 2
121
Interior Temperature
Temperature inside the data acquisition system computer in the baggage bay. [°C]
123
High Voltage Current
High Voltage Current from the tail area of the plane.
124
Heater Current
Total current consumed by de-icing circuits (A).
130
Event Bits
Bits corresponding to various events recognized by the data system, including indications that the system is running, that the in-cloud switch is activated by the pilot (when visually entering cloud), and that the foil impactor is running.
131
GPS Warning Codes
Bits corresponding to various status messages from the GPS system.
140
FSSP size counts
This tag contains information concerning the number of counts in each of the 15 available FSSP size channels. [number per channel per second]
141
FSSP total counts
The total number of droplets counted by the FSSP during a second.
142
FSSP average diameter
The arithmetic average diameter of all droplets recorded during a second. [mm]
143
FSSP concentration
The number of droplets computed from FSSP counts divided by the volume sampled in 1 s. A rudimentary correction for probe activity is made. [# cm-3]
144
FSSP Water
The liquid water concentration computed from the FSSP data for a second. [g m-3]
145
FSSP Activity
The fraction of time the FSSP is logging particles during the current second.
147
2DC Total Shadow Or
Used to acquire the total shadow-or count for the 2DC probe. The total shadow-or count is the number of times the shadow-or output of the probe went active from the last time this data was acquired. [# s-1] The probe samples ~5 liters/s, so shadow-or count divided by 5 liters yields a rough estimate of small precipitation particle concentration.
148
FSSP Equivalent Diameter
deq = 
Also known in the radiation community as effective diameter.
149
Variance in FSSP Equivalent Diameter
Variance around the equivalent diameter, computed as
150
Hail size counts
This tag contains information of the number of particles in each of the 14 hail spectrometer size
Channels. This tag is used by the DISPLAY program only. [number per channel per second]
151
Slow Particle
The number of particles rejected by the hail spectrometer counting circuitry because they
passed through the spectrometer too slowly (indicating they were probably water or ice shed from the probe structure rather than airborne hydrometeors). [number per second]
152
Hail total counts of (150)
Total number of particles accepted by the hail spectrometer. [number per second]
153
Hail average diameter
The average diameter of all particles accepted by the hail spectrometer in the last second. [cm]
154
Hail concentration
The computed concentration corresponding to all particles accepted by the hail spectrometer in the last second. [number per cubic meter]
155
Hail Water
The mass concentration computed from the observed particle spectrum assuming spherical particles and a bulk particle density of 0.9 grams per cubic centimeter. [grams per cubic meter]
160
Top Field Mill
The electric field indicated by the low sensitivity channel on the field mill mounted in the aircraft canopy looking up. Field mill data are recorded at 20 Hz. [kV m-1]
161
Bottom Field Mill
The electric field indicated by the low sensitivity channel on the field mill located in the baggage bay door looking down. [kV m-1]
162
Left Field Mill
The electric field indicated by the low sensitivity channel on the field mill mounted in the left wing tip facing outward. [kV m-1]
163
Right Field Mill
The electric field indicated by the low sensitivity channel on the field mill mounted in the right wing tip facing outward. [kV m-1]
168
Fifth Field Mill
The electric field indicated by the low sensitivity channel on the fifth field mill, located forward in one of the hail spectrometer pylons under the left wing. [kV m-1]
169
Sixth Field Mill
The electric field indicated by the low sensitivity channel on the 6th field mill, located aft in the same hail spectrometer pylon under the left wing (kV m-1)
170
HVPS Total Shadow Or
Did not work as expected during STEPS. [counts]
171
HVPS Housekeeping Data
Stores the counts of the 8 housekeeping channels, which then can be converted in five window temperatures, two video voltages, and laser power readings, all being indicators of the probes proper functionality. This tag is used and displayed by the IDL program called READ_RAW.
172
Latitude
Computed internally in the GPS receiver. [deg]
173
Longitude
Also computed internally in the GPS receiver. [deg]
174
Groundspeed
Computed internally in the GPS receiver (by differentiating position data with respect to time). [m/s]
175
Ground Track Angle
The direction towards which the aircraft is moving relative to the ground, with respect to magnetic north. [deg]
176
Magnetic Deviation
The difference between magnetic north and true north as indicated automatically by the GPS receiver based on the current position. [deg]
177
Time Since Solution
The time since the GPS was last able to compute an accurate position solution based on a sufficient number of satellites. The GPS updates position based on dead reckoning if it does not have a sufficient number of satellites in view. [s]
178
GPS Altitude
Geometric aircraft altitude. [m MSL]]
179
GPS Time
Time recorded from T-28 GPS receiver (UT)
185
GPS Rate Of Climb
Convert Rate of Climb from tenths of feet per minute to m/s.
186
DMT Liquid Water
DMT liquid water [g m-3].
187
DMT Slave
This tag is an indicator of the instrument performance. A voltage level of about 0 volts indicates that current is flowing through the slave coil. A + 5V level indicates that the slave coil has failed.
190
FSSP Gated Strobes
Number of accepted droplet counts. [# s-1]
191
FSSP Total Strobes
Total number of droplet counts. [# s-1]
192
FSSP Reference Voltage
Reference voltage for FSSP opto-electronics.
193
Heading (added in May, 2002)
Magnetic heading in deg. [deg]
205
Altitude
The altitude in a standard atmosphere corresponding to the recorded static pressure. [m]
206
qe
The equivalent potential temperature corresponding to the recorded temperature and assuming saturation with respect to liquid water (should be valid in-cloud). [K]
207
Saturation Mixing Ratio
The mixing ratio of water vapor corresponding to saturation with respect to liquid water at the recorded temperature. [g kg-1]
208
Point dz/dt
The rate of change of altitude of the aircraft computed by differentiating the pressure altitude with respect to time.
209
Indicated Air Speed
What the true airspeed would be if the aircraft were flying at sea level and indicating the observed dynamic pressure. [m s-1]
210
Updraft (uncorrected)
The estimated upward speed of the air relative to the ground computed from changes in the aircraft altitude and other factors, but not corrected for horizontal aircraft acceleration. [m s-1]
211
Calculated TAS
The true speed of the aircraft relative to the air computed from the observed dynamic and static pressures, and temperature. [m s-1]
212
Updraft Correction Factor
A correction to tag 210, the simple (uncorrected) updraft calculation, that accounts for horizontal accelerations of the aircraft. [m s-1]
213
Cooper Updraft
The sum of the uncorrected updraft (210) and the correction factor (211). [m s-1]
214
Kopp Updraft
A more reliable updraft estimate calculated using methods discussed in Kopp, 1985. In most situations, it yields a less noisy and more physically plausible updraft result for the T-28 than the Cooper method. [m s-1]
216
Turbulence
The turbulent energy dissipation rate estimated from the spectrum of observed fluctuations in true airspeed following a method developed by MacCready. [cm2/3 s-1]
217
Air Density
Computed from the recorded temperature and static pressure.
[kg m-3]
219
FSSP Mixing Ratio
The mixing ratio of cloud water per unit mass of dry air calculated from the FSSP water concentration. [g kg-1]
220
Hail Mixing Ratio
The mixing ratio of hail mass per unit mass of dry air based on the computed hail water and air density. [g kg-1]
221
RFT uncorrected
Stores the Reverse Flow Temperature uncorrected value.
244
FSSP equivalent J-W Liquid Water
An estimate of the liquid water concentration a J-W probe should record, based on the observed FSSP droplet spectrum and the assumption that a J-W probe responds incompletely to droplets larger than 30 mm diameter. This tag is provided only in the reduced data file. [g m-3]
260
Ambient Vert Electric Field
The component of the ambient electric field that is vertical in the aircraft frame of reference. Positive means a positive test charge would drift upward relative to the aircraft in the field. [kV m-1]
261
Vert Electric Field due to aircraft charge
The field due to charge on the aircraft, computed by summing the readings of the top and bottom mill and normalizing based on self-charging tests. Positive means a positive test charge would be repelled away from the aircraft due to its charge. [kV m-1]
262
Ambient Hor Electric Field
The ambient field oriented perpendicular to the aircraft along the wings, positive meaning a positive test charge would drift to the left in the field. [kV m-1]
263
Hor Electric Field due to aircraft charge
The field due to charge on the aircraft, computed by summing the wingtip mill readings and normalizing. Positive means a positive charge would be repelled away from the aircraft due to its charge. [kV m-1]
264
Ambient Vert Field (roll cor)
The component of the ambient field that is truly vertical with respect to earth coordinates. [kV m-1]
265
Ambient Hor Field (roll cor)
The component of the ambient field perpendicular to the aircraft path and truly horizontal with respect to earth coordinates. [kV m-1]
266
Ex
X-component of ambient horizontal electric field, relative to the earth system, based on Mo et al (1999). Positive means a positive test charge would drift in the direction of the aircraft motion under the influence of the field.
[kV m-1]
267
Ey
Y-component of ambient horizontal electric field, relative to the earth system, based on Mo et al (1999). Positive means a positive test charge would drift to the left of the direction of the aircraft under the influence of the field. [kV m-1]
268
Ez
Z-component of ambient electric filed, relative to the earth system, based on Mo et al (1999). Positive means a positive test charge would drift upward under the influence of the field. [kV m-1]
269
Ey difference
Difference between tags 267 and 265.
270
Ez difference
Difference between tags 268 and 264.
272
Latitude (deg)
GPS coordinates broken into separate degree and minute components.
273
Latitude (min)
GPS coordinates broken into separate degree and minute components.
274
Longitude (deg)
GPS coordinates broken into separate degree and minute components.
275
Longitude (min)
GPS coordinates broken into separate degree and minute components.
276
Ground Track Angle (True N)
The direction of motion relative to the ground with respect to true north, derived from the GPS ground track angle with respect to magnetic north. [deg]
290
X-acceleration
Acceleration in the direction of aircraft motion. Acceleration backward (deceleration) yields a positive value. [g's]
291
Y-acceleration
Acceleration perpendicular to the direction of aircraft motion, along the direction of the wings. Acceleration toward the left yields a positive value. [g's]
292
Z-acceleration
Vertical acceleration. Upward acceleration produces a positive value. [g's]