List of Variables Recorded During CHILL-TEX 2002 Project with their corresponding Tag number

Parameters recorded or computed within the T-28 dataset are indexed with a tag number. This tag number is used to select data for the display in some of the SDSMT data analysis software.

Tag	Variable	Remarks
100	Time	The T-28 data system is set to UTC, and recorded in a 24-hour format for CHILL-TEX 2002. 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 CHILL-TEX 2002.
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 6^th 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 CHILL-TEX 2002. [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]
193	Heading (added in May, 2002)	Magnetic heading in deg. [deg]
192	FSSP Reference Voltage	Reference voltage for FSSP opto-electronics.
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. [cm^2/3 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]