Upper atmosphere studies Superpressure balloon measurements of ...
Upper atmosphere studies Superpressure balloon measurements of stratospheric electric fields ROBERT H. HOLzwORTH Geophysics Program, AK-50 University of Washington Seattle, Washington 98195
The first prototype flights of a National Science Foundation and National Aeronautics and Space Administration jointly sponsored superpressure balloon experiment were launched from Christchurch, New Zealand in March 1983. The microprocessor-controlled payloads aboard the balloons were designed to obtain long-duration measurements in the stratosphere of the vector electric field and a variety of other electric parameters. The two balloon launches were the first test flights of the payload configuration that will be used for several months beginning in December 1983 to obtain multiple simultaneous stratospheric electric field measurements. The objectives of this experiment include a variety of studies concerned with the interaction and coupling between global electric current systems. This report will summarize the instrumentation and the preliminary results of these test flights. The primary sensors are orthogonal, double-Langmuir probes operated in a high impedance (z > 10 14 (1) mode to measure direct-current electric fields with millivolt-per-meter sensitivity (see Mozer and Serlin 1969). To aid in data interpretation as well as to address other independent scientific questions, the payloads included instruments which measured: (1) very-low-frequency electric power at 1.5, 3, and 6 kilohertz, (2) magnetospheric hiss near 4.5 kilohertz due to wave particle dynamics, (3) positive and negative electric conductivity (Holzworth 1981), (4) background ionization rates (Neher 1953), (5) vector magnetic field, and (6) the optical lightning stroke rate. All sensors were controlled and/or sampled by a dual microprocessor data system using COSMAC 1802 processors. The payload was rotated twice a minute to eliminate direct-current electronic offset effects, and the data were averaged and transmitted to the ARGOS polar-orbiting data-collection platform. Further details on the instrumentation are found in Schroeder and others (1981) and Holzworth (1983). Both prototype flights were successful. All electric field sensors worked flawlessly, and ultraviolet probe degradation did not appear to be a problem even several weeks into each flight. Figure 1 shows the known (as of this writing) trajectories at 26 kilometers altitude. Figure 2 shows a sample of the raw 1983 REVIEW
double-probe electric-field data from payload EMA 1 (for electrodynamics of the middle atmosphere). The two panels show totally independent data sets from the two perpendicular pair of horizontal probes. These probes are rotated about a vertical axis resulting in a quasi-sinusoidal output. One can see from figure 2 that both probes recorded the same basic envelope of electricfield variations even though turbulence on a time scale of a few minutes was often observed. The raw data is sampled once every 5 seconds resulting in six points per rotation and probe output V43 leads V21 by 90°. As an example of the analyzed (i.e., despun) electric-field data, figure 3 shows 10-minute average data from a thunderstorm. The vertical electric field becomes inverted in polarity, and the horizontal field obtains a similar magnitude with slowly varying direction as the storm is passed over or dissipates. This signature is very similar to storms seen in the Northern Hemisphere (cf. Holzworth 1981). With the successful test flight of the prototype payloads, the main experiment goals can be addressed on schedule with a series of flights to begin in December 1983. The main scientific objectives of these flights are studies of magnetospheric/at-
çç1 0° E4s
90
90°
Figure 1. Trajectories of two superpressure balloon flights at 26kilometer altitude launched from Christchurch, New Zealand in March and April 1983.
255
+ 67
EMA I
I-
90 60 CONDUCTIVITY
(mvm)
ANEGAT IVE
VCONDUCTIVITY
LLJ
-67
+ 67
20
- 2.0
(mvn) 0
-67 0
30
MINUTES AFTER 0517 UT 9 MARCH 1983
60 83
Figure 2. Raw electric-field data from two independent sensors on one payload indicating a large degree of turbulence in the midlatitude stratospheric electric field. ("UT" denotes universal time; "mv/rn" denotes millivolts per meter.)
mospheric electrical coupling, global response to a solar flare or major magnetic storm, and spatial and temporal electric turbulence. The instruments for this international collaboration were designed and built by personnel at the University of Washington, Cornell University, Utah State University, Stanford University, the University of Otago (New Zealand), the Aerospace Corporation, and the National Center for Atmospheric Research. The co-investigators and principal staff at these institutions were M. Kelley, P. Kintner, S. Powell*, A. Shaw, R. Williamson, R. Dowden*, B. Edgar, T. Onsager* , D. Boulter* , V. Lally*, N. Carlson*, J. Smalley*, and E. Lichtfield* . This research was jointly sponsored by the National Science Foundation and the National Aeronautics and Space Administration under grant ATM 82-12283. *
At the launch site in March and April 1983.
256
20 E 10 00
U VERTICAL E FIELD
-f
^FF
7
.
-
he
HORIZONTAL E MAGNITUDE
HOR IZ ONTAL DIRECTION
II 12 13 14 15 16 17 UT March 24, 1983 EMA I (44.5S, I30*W)
Figure 3. Typical thunderstorm signature in the stratospheric electric field as seen in the 10-minute average data from EMA 1.
References Holzworth, R. H. 1981. High latitude stratospheric electrical measurements in fair and foul weather under various solar conditions. Journal of Atmospheric and Terrestrial Physics, 43, 1115. Holzworth, R. H. 1983. Electrodynamics of the stratosphere using 5000 m3 superpressure balloons. In W. Reidler and M. Friedrich (Eds.), Scientific ballooning III. Oxford: Pergamon Press. Mozer, F. S., and R. Serlin. 1969. Magnetospheric electric field measurements with balloons. Journal of Geophysical Research, 74, 4739. Neher, H. V. 1953. An automatic ionization chamber. Reviews of Scientific Instruments, 24(2), 99. Schroeder, K., P. Kintner, C. Cornish, R. Green, and R. Holzworth. 1981. in-situ data analysis on high altitude balloons using microprocessors. Transactions of the Institute of Electrical and Electronic Engineers, on Geoscience and Remote Sensing, Vol. GE-19, 129.
ANTARCTIC JOURNAL
The first prototype flights of a National Science Foundation and National Aeronautics and Space Administration jointly sponsored superpressure balloon experiment were launched from Christchurch, New Zealand in March 1983. The microprocessor-controlled payloads aboard the balloons were designed to obtain long-duration measurements in the stratosphere of the vector electric field and a variety of other electric parameters. The two balloon launches were the first test flights of the payload configuration that will be used for several months beginning in December 1983 to obtain multiple simultaneous stratospheric electric field measurements. The objectives of this experiment include a variety of studies concerned with the interaction and coupling between global electric current systems. This report will summarize the instrumentation and the preliminary results of these test flights. The primary sensors are orthogonal, double-Langmuir probes operated in a high impedance (z > 10 14 (1) mode to measure direct-current electric fields with millivolt-per-meter sensitivity (see Mozer and Serlin 1969). To aid in data interpretation as well as to address other independent scientific questions, the payloads included instruments which measured: (1) very-low-frequency electric power at 1.5, 3, and 6 kilohertz, (2) magnetospheric hiss near 4.5 kilohertz due to wave particle dynamics, (3) positive and negative electric conductivity (Holzworth 1981), (4) background ionization rates (Neher 1953), (5) vector magnetic field, and (6) the optical lightning stroke rate. All sensors were controlled and/or sampled by a dual microprocessor data system using COSMAC 1802 processors. The payload was rotated twice a minute to eliminate direct-current electronic offset effects, and the data were averaged and transmitted to the ARGOS polar-orbiting data-collection platform. Further details on the instrumentation are found in Schroeder and others (1981) and Holzworth (1983). Both prototype flights were successful. All electric field sensors worked flawlessly, and ultraviolet probe degradation did not appear to be a problem even several weeks into each flight. Figure 1 shows the known (as of this writing) trajectories at 26 kilometers altitude. Figure 2 shows a sample of the raw 1983 REVIEW
double-probe electric-field data from payload EMA 1 (for electrodynamics of the middle atmosphere). The two panels show totally independent data sets from the two perpendicular pair of horizontal probes. These probes are rotated about a vertical axis resulting in a quasi-sinusoidal output. One can see from figure 2 that both probes recorded the same basic envelope of electricfield variations even though turbulence on a time scale of a few minutes was often observed. The raw data is sampled once every 5 seconds resulting in six points per rotation and probe output V43 leads V21 by 90°. As an example of the analyzed (i.e., despun) electric-field data, figure 3 shows 10-minute average data from a thunderstorm. The vertical electric field becomes inverted in polarity, and the horizontal field obtains a similar magnitude with slowly varying direction as the storm is passed over or dissipates. This signature is very similar to storms seen in the Northern Hemisphere (cf. Holzworth 1981). With the successful test flight of the prototype payloads, the main experiment goals can be addressed on schedule with a series of flights to begin in December 1983. The main scientific objectives of these flights are studies of magnetospheric/at-
çç1 0° E4s
90
90°
Figure 1. Trajectories of two superpressure balloon flights at 26kilometer altitude launched from Christchurch, New Zealand in March and April 1983.
255
+ 67
EMA I
I-
90 60 CONDUCTIVITY
(mvm)
ANEGAT IVE
VCONDUCTIVITY
LLJ
-67
+ 67
20
- 2.0
(mvn) 0
-67 0
30
MINUTES AFTER 0517 UT 9 MARCH 1983
60 83
Figure 2. Raw electric-field data from two independent sensors on one payload indicating a large degree of turbulence in the midlatitude stratospheric electric field. ("UT" denotes universal time; "mv/rn" denotes millivolts per meter.)
mospheric electrical coupling, global response to a solar flare or major magnetic storm, and spatial and temporal electric turbulence. The instruments for this international collaboration were designed and built by personnel at the University of Washington, Cornell University, Utah State University, Stanford University, the University of Otago (New Zealand), the Aerospace Corporation, and the National Center for Atmospheric Research. The co-investigators and principal staff at these institutions were M. Kelley, P. Kintner, S. Powell*, A. Shaw, R. Williamson, R. Dowden*, B. Edgar, T. Onsager* , D. Boulter* , V. Lally*, N. Carlson*, J. Smalley*, and E. Lichtfield* . This research was jointly sponsored by the National Science Foundation and the National Aeronautics and Space Administration under grant ATM 82-12283. *
At the launch site in March and April 1983.
256
20 E 10 00
U VERTICAL E FIELD
-f
^FF
7
.
-
he
HORIZONTAL E MAGNITUDE
HOR IZ ONTAL DIRECTION
II 12 13 14 15 16 17 UT March 24, 1983 EMA I (44.5S, I30*W)
Figure 3. Typical thunderstorm signature in the stratospheric electric field as seen in the 10-minute average data from EMA 1.
References Holzworth, R. H. 1981. High latitude stratospheric electrical measurements in fair and foul weather under various solar conditions. Journal of Atmospheric and Terrestrial Physics, 43, 1115. Holzworth, R. H. 1983. Electrodynamics of the stratosphere using 5000 m3 superpressure balloons. In W. Reidler and M. Friedrich (Eds.), Scientific ballooning III. Oxford: Pergamon Press. Mozer, F. S., and R. Serlin. 1969. Magnetospheric electric field measurements with balloons. Journal of Geophysical Research, 74, 4739. Neher, H. V. 1953. An automatic ionization chamber. Reviews of Scientific Instruments, 24(2), 99. Schroeder, K., P. Kintner, C. Cornish, R. Green, and R. Holzworth. 1981. in-situ data analysis on high altitude balloons using microprocessors. Transactions of the Institute of Electrical and Electronic Engineers, on Geoscience and Remote Sensing, Vol. GE-19, 129.
ANTARCTIC JOURNAL
