Instruments:akl

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Last Revised 06/25/2011 by emery@ucar.edu

Arecibo Potassium Lidar

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Contents


Contact Persons

Web Sites

Acknowledgments

The Arecibo Observatory potassium lidar is operated by the National Astronomy and Ionosphere Center (NAIC), which is operated by Cornell University under a cooperative agreement with the National Science Foundation.

To offer co-authorship (part of the CEDAR DB Rules of the Road) or acknowledgment in your publications using results from the Arecibo K lidar, we ask that you contact the head of the Space and Atmospheric Sciences Department at Arecibo (Sixto Gonzalez at sixto@naic.edu) or the Arecibo scientist responsible for the data (Jonathan Friedman at jonathan@naic.edu or at jsf16@cornell.edu).

Processing Code

  • KLidarPhotons2Density IDL code to convert photons at 3 filters to potassium density [K] written by Jonathan Friedman of the Arecibo Observatory about his potassium lidar. (A CEDAR DB login is needed to access this code.)

Data Description

The Arecibo potassium [K] lidar is located at Arecibo, Puerto Rico at (18.35N, 66.75W or 293.25E), 360 m above sea level. It was developed with CEDAR and NASA support and has been in operation since 1999. The meteoric metallic layers, which include potassium, are located between about 80 and 105 km altitude, with a peak near 91 km. At the end of 2001 at 92 km, the apex magnetic lat,lon coordinates were (28.53, 10.16), where the magnetic inclination and declination angles were 45.41 deg and -12.26 deg. The magnetic local time at 0 UT is 1933 MLT. The solar local time (SLT, code 44) is UT + -66.75/15 or UT-4.45h. The data are currently only available at night. The instrument looks in the vertical direction (azimuth code 130 = 0 default and elevation code 140 = 9000).

The 3-frequency lidar system uses an acousto-optic modulator, which was invented by the CSU lidar group, to shift the laser between 3 frequencies on the K spectrum for temperature measurements. The center frequency Sf0 is -180 MHz from the centroid frequency of the K spectrum, and the off center frequencies are shifted by the acousto-optic modulators. The centroid potassium wavelength in air is at 769.898 nm (code 2400) and is 770.1093 nm in a vacuum. The centroid frequency (=c/wavelength) is at 389.42e+12Hz. For data prior to February 2006, the modulated frequencies are -657.6 MHz from the centroid frequency at Sfl (-477.6 MHz from Sf0) and +297.6 MHz at Sfh (+477.6 MHz from Sf0). Starting in 06092, these off center frequencies changed to -421.0 MHz and +498.0 MHz from the centroid (or -241.0 and +678.0 MHz from Sf0). The signal Sf0 at the central line is taken first, followed by the frequencies lower than (Sfl) and higher than (Sfh) the central line at Sf0 (and the centroid measured by code 2405).

The receiver system employs a GaAs photomultiplier tube in photon counting mode. It is protected from strong light scattering from low altitudes by a rotating wheel shutter, which is phase locked to the laser firing. This shutter became a permanent part of the lidar in March 2005. Prior to that time, electronic gating of the detector was used, but the PMT was susceptable to saturation in hazy conditions, which required us to restrict some data sets (these are not included in the CDB). All light below 10 km is blocked, and the shutter is fully open at altitudes slightly above 20 km.

The central signal Sf0 is then coupled with the off-center frequencies, Sfl and Sfh, in the following ratios: (Sfh + Sfl)/Sf0 and Sfh/Sfl. The former is primarly sensitive to temperature and the latter to the offset of the spectrum from the true K spectrum. This offset can be caused by Doppler shift, thus allowing for wind measurements, but for the Arecibo K lidar the offset is dominated by nonlinear frequency chirp in the laser, and this ratio is used to compensate for the chirp and correct the resulting temperature measurement.

Integrations modes are of two types. Prior to April 2006, we were able to pulse-to-pulse switch between laser frequencies, and thus the profiles for all three were obtained simultaneously. At that time, 2000 laser shots were accumulated for a data cycle, 1000 at the center frequency and 500 at each wing frequency. The laser typically operated at 30 Hz, which meant that it took approximately 2000/30 = 66.7 seconds to record a profile. After changing AOMs in March 2006, we were required to use a different integration method. A single integration for those data consists of three separate integrations, one at each AOM state. Each integration typically accumulates data from 600 laser pulses sent out at 31 Hz (or 31 pulses per second), the laser rep rate having changed around that time as well. Thus, it takes 600/31Hz = 19.355 sec to record a signal or profile. Before the end of 2009, it took 0.5-1.5 sec to go from one frequency to another, so the whole sequence takes a little over 60 sec or 1 minute. However, due to characteristics of the laser (it does not fire if the cavity is out of resonance with its seed source), the time to take a single profile is usually longer than the ideal time of 66.7 sec (pre-April 2006) or 19.355 sec (post-April 2006).

The raw photon counts are stored from the ground to 300 km with a normal range bin of 150 m. The error bar in the counts is not given but can be calculated, as photon counting obeys Poisson statistics, to be the square root of the counts per range bin. The height range for the raw counts is usually 2000 bins of width 0.15 km between 0.30 to 300.15 km, while there are 400 bins for the [K] values from 70.05 to 129.90 km, which is a subset from bins #466-865 of the 2000 raw photon count range bins. The potassium density [K] is only sampled in the first (or central) frequency, and so has the same time as the raw photon counts when that frequency is sampled, approximately every minute. The beginning of each frequency profile of the raw photon counts were saved originally in Atlantic Standard Time (AST) which is UT-4h. The Tn values were saved in SLT, which is UT-4.45h, at the mean of all the start times of the 3 frequencies, averaged over approximately 30 minutes (~23 frequency sets) and usually 450 m range resolution (~3 height bins). The UT (code 34) and SLT (code 44) times for the raw counts (and [K]) and Tn are approximate midpoint times.

The temperature analysis and binning can be altered by the analysis code, which will soon be available from the CEDAR Database. Temperatures >500 K and negative values of the temperature and density were set to missing (-32767), but it is advisable to delete Tn where the error bar exceeds 30 K, or when the temperature is below 140 K or above 300 K. Raw counts were set to missing for cirrus clouds around 10 km, and for bogus periods.

Daytime observations are in the process of being implemented, and two data sets, from June 2009, have some daytime temperatures. This is done by adding a Faraday Anomalous Dispersion Optical Filter (FADOF) to the receiver chain. Daytime observations are not a standard data product.

Revision

All data from 2003-2010 were revised using consistent methods of removing the background noise and reviewing data quality in May 2011.

Key references for the technology of and the science derived from the Arecibo potassium [K] lidar

  1. Friedman, J.S., S.C. Collins, R. Delgado, and P.A. Castleberg (2002), Mesospheric potassium layer over the Arecibo Observatory, N, W, Geophys. Res. Lett., 29(5), 1071, 10.1029/2001GL013542.
  2. Friedman, J.S., C.A. Tepley, S. Raizada, Q.H. Zhou, J. Hedin, and R. Delgado (2003), Potassium Doppler-resonance lidar for the study of the mesosphere and lower thermosphere at the Arecibo Observatory, J. Atmos. Sol. Terr. Phys., 65(16-18), 1411-1424, 10.1016/S1364-6826(03)00205-0.
  3. Friedman, J.S. (2003), Tropical mesopause climatology over the Arecibo Observatory, Geophys. Res. Letters, 30(12), 1642, 10.1029/2003GL016966.
  4. Friedman, J.S. (2006), The Arecibo potassium lidar daylight receiver, in 23rd International Laser Radar Conference, edited by C. Nagasawa and N. Sugimoto, pp. 557-560, ILRC.
  5. Friedman, J.S., and X. Chu (2007), Nocturnal temperature structure in the mesopause region over the Arecibo Observatory : Seasonal variations, J. Geophys. Res., 112, D14,107, 10.1029/2006JD008220.
  6. Friedman, J.S., I. Gonzalez, and W. Huang (2008), Faraday filter: A comparison between hot and cold cell design, in Proceedings of the 24 International Laser Radar Conference, vol. II, edited by Organizing Committee of the 24 International Laser Radar Conference, p. 835, International Laser Radar Conference, ILRC.
  7. Friedman, J.S., X. Zhang, X. Chu, and J.M. Forbes (2009), Longitudinal variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space, J. Geophys. Res., 114, D11,114, 10.1029/2009JD011763.
  8. Friedman, J.S., X. Zhang, X. Chu, and J.M. Forbes (2010), Low-latitude thermal semidiurnal tide: longitudinal and seasonal variations based on ground-based measurements from Arecibo and Maui, space-based measurements by SABER, and modeling with GSWM-02, in Remote Sensing of Clouds and the Atmosphere XV, vol. 7827, edited by R.H. Picard, K. Schaefer, A. Comeron, and M. van Weele, SPIE, 10.1117/12.865057.
  9. Hoeffner, J., and J.S. Friedman (2004), The mesospheric metal layer topside: a possible connection to meteoroids, Atmos. Chem. Phys., 4, 801-808.
  10. Hoeffner, J., and J.S. Friedman (2005), The mesospheric metal layer topside: Examples of simultaneous metal observations, J. Atmos. Sol. Terr. Phys., 67, 1226-1237, 10.1016/j.jastp.2005.06.010
  11. Raizada, S., C.A. Tepley, D. Janches, J.S. Friedman, Q. Zhou, and J.D. Mathews (2004), Lidar observations of Ca and K metallic layers from Arecibo and comparison with micrometeor sporadic activity, J. Atmos. Sol. Terr. Phys., 66, 595-606, 10.1016/j.jastp.2004.01.030.
  12. Zhou, Q., J. Friedman, S. Raizada, C. Tepley, and Y.T. Morton (2005), Morphology of nighttime ion, potassium and sodium layers in the meteor zone above Arecibo, J. Atmos. Sol. Terr. Phys., 67, 1245-1257, 10.1016/j.jastp.2005.06.013.

Summary Plots for Arecibo Potassium Lidar

These plots are of the neutral temperature only, which is usually provided in 30 min time and 450 m height bins. The potassium density is available but not plotted in bins which are usually 1 min in time and 150 m in height between 70-130 km. The raw counts are also available but not plotted at 3 different frequencies at the same binning as [K] except extended from 0-300km. The code to analyze the raw counts is available at the CEDAR database, with a link above.

2003

  1. 2003 days 352-353 or moda 1218-1219 All data for this period
  2. 2003 days 353-354 or moda 1219-1220 All data for this period
  3. 2003 days 354-355 or moda 1220-1221 All data for this period

2004

  1. 2004 days 019-020 or moda 0119-0120 All data for this period
  2. 2004 days 021-022 or moda 0121-0122 All data for this period
  3. 2004 days 022-023 or moda 0122-0123 All data for this period
  4. 2004 days 023-024 or moda 0123-0124 All data for this period
  5. 2004 days 082-083 or moda 0322-0323 All data for this period
  6. 2004 days 083-084 or moda 0323-0324 All data for this period
  7. 2004 days 108-109 or moda 0417-0418 All data for this period
  8. 2004 days 135-136 or moda 0514-0515 All data for this period
  9. 2004 days 139-140 or moda 0518-0519 All data for this period
  10. 2004 days 166-167 or moda 0614-0615 All data for this period
  11. 2004 days 167-168 or moda 0615-0616 All data for this period
  12. 2004 days 168-169 or moda 0616-0617 All data for this period
  13. 2004 days 196-197 or moda 0714-0715 All data for this period
  14. 2004 days 197-198 or moda 0715-0716 All data for this period
  15. 2004 days 198-199 or moda 0716-0717 All data for this period
  16. 2004 days 199-200 or moda 0717-0718 All data for this period
  17. 2004 days 200-201 or moda 0718-0719 All data for this period
  18. 2004 days 212-213 or moda 0730-0731 All data for this period
  19. 2004 days 223-224 or moda 0810-0811 All data for this period
  20. 2004 days 224-225 or moda 0811-0812 All data for this period
  21. 2004 days 225-226 or moda 0812-0813 All data for this period
  22. 2004 days 226-227 or moda 0813-0814 All data for this period
  23. 2004 days 229-230 or moda 0816-0817 All data for this period
  24. 2004 days 230-231 or moda 0817-0818 All data for this period
  25. 2004 days 231-232 or moda 0818-0819 All data for this period
  26. 2004 days 232-233 or moda 0819-0820 All data for this period
  27. 2004 days 285-286 or moda 1011-1012 All data for this period
  28. 2004 days 310-311 or moda 1105-1106 All data for this period
  29. 2004 days 345-346 or moda 1210-1211 All data for this period

2005

  1. 2005 days 038-039 or moda 0207-0208 All data for this period
  2. 2005 days 039-040 or moda 0208-0209 All data for this period
  3. 2005 days 040-041 or moda 0209-0210 All data for this period
  4. 2005 days 041-042 or moda 0210-0211 All data for this period
  5. 2005 days 042-043 or moda 0211-0212 All data for this period
  6. 2005 days 064-065 or moda 0305-0306 All data for this period
  7. 2005 days 069-070 or moda 0310-0311 All data for this period
  8. 2005 days 070-071 or moda 0311-0312 All data for this period
  9. 2005 days 071-072 or moda 0312-0313 All data for this period
  10. 2005 days 072-073 or moda 0313-0314 All data for this period
  11. 2005 days 073-074 or moda 0314-0315 All data for this period
  12. 2005 days 076-077 or moda 0317-0318 All data for this period
  13. 2005 days 077-078 or moda 0318-0319 All data for this period
  14. 2005 days 078-079 or moda 0319-0320 All data for this period
  15. 2005 days 081-082 or moda 0322-0323 All data for this period
  16. 2005 days 098-099 or moda 0408-0409 All data for this period
  17. 2005 days 099-100 or moda 0409-0410 All data for this period
  18. 2005 days 100-101 or moda 0410-0411 All data for this period
  19. 2005 days 101-102 or moda 0411-0412 All data for this period
  20. 2005 days 102-103 or moda 0412-0413 All data for this period
  21. 2005 days 103-104 or moda 0413-0414 All data for this period
  22. 2005 days 104-105 or moda 0414-0415 All data for this period
  23. 2005 days 105-106 or moda 0415-0416 All data for this period
  24. 2005 days 111-112 or moda 0421-0422 All data for this period
  25. 2005 days 113-114 or moda 0423-0424 All data for this period
  26. 2005 days 114-115 or moda 0424-0425 All data for this period
  27. 2005 days 115-116 or moda 0425-0426 All data for this period
  28. 2005 days 117-118 or moda 0427-0428 All data for this period
  29. 2005 days 118-119 or moda 0428-0429 All data for this period
  30. 2005 days 141-142 or moda 0521-0522 All data for this period
  31. 2005 days 146-147 or moda 0526-0527 All data for this period
  32. 2005 days 157-158 or moda 0606-0607 All data for this period
  33. 2005 days 165-166 or moda 0614-0615 All data for this period
  34. 2005 days 166-167 or moda 0615-0616 All data for this period
  35. 2005 days 189-190 or moda 0708-0709 All data for this period
  36. 2005 days 213-214 or moda 0801-0802 All data for this period
  37. 2005 days 215-216 or moda 0803-0804 All data for this period
  38. 2005 days 216-217 or moda 0804-0805 All data for this period
  39. 2005 days 217-218 or moda 0805-0806 All data for this period
  40. 2005 days 221-222 or moda 0809-0810 All data for this period
  41. 2005 days 251-252 or moda 0908-0909 All data for this period
  42. 2005 days 253-254 or moda 0910-0911 All data for this period
  43. 2005 days 254-255 or moda 0911-0912 All data for this period
  44. 2005 days 258-259 or moda 0915-0916 All data for this period
  45. 2005 days 264-265 or moda 0921-0922 All data for this period
  46. 2005 days 265-266 or moda 0922-0923 All data for this period
  47. 2005 days 278-279 or moda 1005-1006 All data for this period
  48. 2005 days 279-280 or moda 1006-1007 All data for this period
  49. 2005 days 280-281 or moda 1007-1008 All data for this period
  50. 2005 days 299-300 or moda 1026-1027 All data for this period
  51. 2005 days 310-311 or moda 1106-1107 All data for this period
  52. 2005 days 311-312 or moda 1107-1108 All data for this period
  53. 2005 days 312-313 or moda 1108-1109 All data for this period
  54. 2005 days 313-314 or moda 1109-1110 All data for this period
  55. 2005 days 314-315 or moda 1110-1111 All data for this period
  56. 2005 days 353-354 or moda 1219-1220 All data for this period
  57. 2005 days 354-355 or moda 1220-1221 All data for this period
  58. 2005 days 355-356 or moda 1221-1222 All data for this period
  59. 2005 days 356-357 or moda 1222-1223 All data for this period

2006

  1. 2006 days 011-012 or moda 0111-0112 All data for this period
  2. 2006 days 023-024 or moda 0123-0124 All data for this period
  3. 2006 days 024-025 or moda 0124-0125 All data for this period
  4. 2006 days 025-026 or moda 0125-0126 All data for this period
  5. 2006 days 030-031 or moda 0130-0131 All data for this period
  6. 2006 days 092-093 or moda 0402-0403 All data for this period
  7. 2006 days 109-110 or moda 0419-0420 All data for this period
  8. 2006 days 115-116 or moda 0425-0426 All data for this period
  9. 2006 days 149-150 or moda 0529-0530 All data for this period
  10. 2006 days 150-151 or moda 0530-0531 All data for this period
  11. 2006 days 183-184 or moda 0702-0703 All data for this period
  12. 2006 days 240-241 or moda 0828-0829 All data for this period
  13. 2006 days 241-242 or moda 0829-0830 All data for this period
  14. 2006 days 263-264 or moda 0920-0921 All data for this period
  15. 2006 days 264-265 or moda 0921-0922 All data for this period
  16. 2006 days 265-266 or moda 0922-0923 All data for this period
  17. 2006 days 266-267 or moda 0923-0924 All data for this period
  18. 2006 days 320-321 or moda 1116-1117 All data for this period
  19. 2006 days 321-322 or moda 1117-1118 All data for this period
  20. 2006 days 322-323 or moda 1118-1119 All data for this period
  21. 2006 days 323-324 or moda 1119-1120 All data for this period
  22. 2006 days 349-350 or moda 1215-1216 All data for this period
  23. 2006 days 350-351 or moda 1216-1217 All data for this period

2007

  1. 2007 days 022-023 or moda 0122-0123 All data for this period
  2. 2007 days 023-024 or moda 0123-0124 All data for this period
  3. 2007 days 075-076 or moda 0316-0317 All data for this period
  4. 2007 days 076-077 or moda 0317-0318 All data for this period
  5. 2007 days 077-078 or moda 0318-0319 All data for this period
  6. 2007 days 078-079 or moda 0319-0320 All data for this period
  7. 2007 days 227-228 or moda 0815-0816 All data for this period

2008

  1. 2008 days 018-019 or moda 0118-0119 All data for this period
  2. 2008 days 019-020 or moda 0119-0120 All data for this period
  3. 2008 days 020-021 or moda 0120-0121 All data for this period
  4. 2008 days 022-023 or moda 0122-0123 All data for this period
  5. 2008 days 023-024 or moda 0123-0124 All data for this period
  6. 2008 days 024-025 or moda 0124-0125 All data for this period
  7. 2008 days 062-063 or moda 0302-0303 All data for this period
  8. 2008 days 099-100 or moda 0408-0409 All data for this period
  9. 2008 days 183-184 or moda 0701-0702 All data for this period
  10. 2008 days 184-185 or moda 0702-0703 All data for this period
  11. 2008 days 190-191 or moda 0708-0709 All data for this period
  12. 2008 days 192-193 or moda 0710-0711 All data for this period
  13. 2008 days 210-211 or moda 0728-0729 All data for this period
  14. 2008 days 242-243 or moda 0829-0830 All data for this period
  15. 2008 days 243-244 or moda 0830-0831 All data for this period
  16. 2008 days 244-245 or moda 0831-0901 All data for this period
  17. 2008 days 273-274 or moda 0929-0930 All data for this period

2009

  1. 2009 days 054-055 or moda 0223-0224 All data for this period
  2. 2009 days 106-107 or moda 0416-0417 All data for this period
  3. 2009 days 168-169 or moda 0617-0618 All data for this period
  4. 2009 days 198-199 or moda 0717-0718 All data for this period
  5. 2009 days 201-202 or moda 0720-0721 All data for this period
  6. 2009 days 203-204 or moda 0722-0723 All data for this period
  7. 2009 days 204-205 or moda 0723-0724 All data for this period
  8. 2009 days 205-206 or moda 0724-0725 All data for this period
  9. 2009 days 318-319 or moda 1114-1115 All data for this period
  10. 2009 days 341-342 or moda 1207-1208 All data for this period
  11. 2009 days 342-343 or moda 1208-1209 All data for this period
  12. 2009 days 343-344 or moda 1209-1210 All data for this period
  13. 2009 days 344-345 or moda 1210-1211 All data for this period
  14. 2009 days 346-347 or moda 1212-1213 All data for this period
  15. 2009 days 348-349 or moda 1214-1215 All data for this period

2010

  1. 2010 days 021-022 or moda 0121-0122 All data for this period
  2. 2010 days 022-023 or moda 0122-0123 All data for this period
  3. 2010 days 024-025 or moda 0124-0125 All data for this period


New Plots May11 vs Old Plots Mar11

These are plots from the re-analysis done in May 2011 with some comparisons for older analyses.

Much Improved New Plots, but still some questions

There are some days where some columns of temperatures seem to be relatively cool such as starting daynumbers in 2005 (64,70,72,73,115,141), 2006 (150,240,321,350), 2007 (22,75), 2008 (22,99,243,244,273), 2009 (203,205,318). Be careful and contact Jonathan Friedman before use to check on quality.

  1. OLD 2005 days 115-116 or moda 0425-0426 All data for this period
  2. NEW 2005 days 115-116 or moda 0425-0426 All data for this period
  3. OLD 2006 days 240-241 or moda 0828-0829 All data for this period
  4. NEW 2006 days 240-241 or moda 0828-0829 All data for this period
  5. OLD 2006 days 321-322 or moda 1117-1118 All data for this period
  6. NEW 2006 days 321-322 or moda 1117-1118 All data for this period
  7. OLD 2008 days 022-023 or moda 0122-0123 All data for this period
  8. NEW 2008 days 022-023 or moda 0122-0123 All data for this period
  9. OLD 2008 days 099-100 or moda 0408-0409 All data for this period
  10. NEW 2008 days 099-100 or moda 0408-0409 All data for this period
  11. OLD 2008 days 243-244 or moda 0830-0831 All data for this period
  12. NEW 2008 days 243-244 or moda 0830-0831 All data for this period
  13. OLD 2008 days 244-245 or moda 0831-0901 All data for this period
  14. NEW 2008 days 244-245 or moda 0831-0901 All data for this period
  15. OLD 2009 days 318-319 or moda 1114-1115 All data for this period
  16. NEW 2009 days 318-319 or moda 1114-1115 All data for this period

Nights Missing - Can they be rescued?

  1. 2004 days 225-226 or moda 0812-0813 All data for this period
  2. 2006 days 109-110 or moda 0419-0420 All data for this period
  3. 2006 days 350-351 or moda 1216-1217 All data for this period
  4. 2007 days 227-228 or moda 0815-0816 All data for this period
  5. 2008 days 020-021 or moda 0120-0121 All data for this period
  6. 2008 days 242-243 or moda 0829-0830 All data for this period
  7. 2009 days 198-199 or moda 0717-0718 All data for this period
  8. 2009 days 201-202 or moda 0720-0721 All data for this period
  9. 2009 days 203-204 or moda 0722-0723 All data for this period
  10. 2009 days 204-205 or moda 0723-0724 All data for this period
  11. 2009 days 205-206 or moda 0724-0725 All data for this period