Abstract

An analysis is presented on the passive standoff detection and identification of Bacillus subtilis (BG) clouds with the Compact ATmospheric Sounding Interferometer (CATSI) sensor. This research is based on recent spectral measurements obtained during the Technology Readiness Evaluation trial held July 2002 at Dugway Proving Ground, Utah. Results obtained from three trial BG cloud episodes are used to explain and demonstrate the detection capability of the CATSI sensor. The BG clouds were measured at a distance of 3 km from the sensor in a near-horizontal path scenario. It was found that the low thermal contrast of approximately 0.2 K between the BG cloud and the background yielded weak but observable spectral signatures. The processing of the spectral signatures with the GASeous Emission Monitoring (GASEM) algorithm has provided a rough estimate of BG cloud column densities. The results of a series of simulations with the FASCOD3 transmission model have shown that the detection sensitivity for BG can be greatly improved for both slant path uplooking and downlooking scenarios.

© 2003 Optical Society of America

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References

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  1. G. Laufer, A. Ben-David, “Optimized differential absorption radiometer for remote sensing of chemical effluents,” Appl. Opt. 41, 2263–2273 (2002).
    [CrossRef] [PubMed]
  2. C. T. Chaffin, T. L. Marshall, N. C. Chaffin, “Passive FT-IR remote sensing of smokestack emissions,” Field Anal. Chem. Technol. 3, 111–115 (1999).
    [CrossRef]
  3. D. F. Flanigan, “Hazardous cloud imaging: a new way of using passive infrared,” Appl. Opt. 36, 7027–7036 (1997).
    [CrossRef]
  4. D. A. Ligon, A. E. Wetmore, P. S. Gillespie, “Simulation of the passive infrared spectral signatures of bioaerosol and natural fog clouds immersed in the background atmosphere,” Opt. Express 10, 909–919 (2002), http://www.opticsexpress.org .
    [CrossRef] [PubMed]
  5. S. Luo, D. O. Anderson, A. J. Mohr, Abbreviated Test Plan for Technology Readiness Evaluation for Biological Standoff Detection System, Dugway Proving Ground Document WDTC-TP-02-026 (West Desert Test Center, U.S. Army Dugway Proving Ground, Dugway, Utah, June 2002).
  6. S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.
  7. J.-M. Thériault, “Modeling the responsivity and self-emission of a double-beam Fourier-transform infrared interferometer,” Appl. Opt. 38, 505–515 (1999).
    [CrossRef]
  8. J.-M. Thériault, Passive Standoff Detection of Chemical Vapors by Differential FTIR Radiometry, Defence Research Establishment Valcartier Technical Report TR-2000-156 (Defence Research and Development Canada—Valcartier, Val-Belair, Quebec, Canada, 2001).
  9. D. F. Flanigan, R. W. Doherty, A. C. Samuels, Infrared Absorptivity of Bacillus Subtilis (BG) and Several Battlefield Aerosols, Rep. ECBC-TR-118 (Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Md., 2000).

2002

1999

C. T. Chaffin, T. L. Marshall, N. C. Chaffin, “Passive FT-IR remote sensing of smokestack emissions,” Field Anal. Chem. Technol. 3, 111–115 (1999).
[CrossRef]

J.-M. Thériault, “Modeling the responsivity and self-emission of a double-beam Fourier-transform infrared interferometer,” Appl. Opt. 38, 505–515 (1999).
[CrossRef]

1997

Abreu, L. W.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Anderson, D. O.

S. Luo, D. O. Anderson, A. J. Mohr, Abbreviated Test Plan for Technology Readiness Evaluation for Biological Standoff Detection System, Dugway Proving Ground Document WDTC-TP-02-026 (West Desert Test Center, U.S. Army Dugway Proving Ground, Dugway, Utah, June 2002).

Anderson, G. P.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Ben-David, A.

Chaffin, C. T.

C. T. Chaffin, T. L. Marshall, N. C. Chaffin, “Passive FT-IR remote sensing of smokestack emissions,” Field Anal. Chem. Technol. 3, 111–115 (1999).
[CrossRef]

Chaffin, N. C.

C. T. Chaffin, T. L. Marshall, N. C. Chaffin, “Passive FT-IR remote sensing of smokestack emissions,” Field Anal. Chem. Technol. 3, 111–115 (1999).
[CrossRef]

Chetwynd, J. H.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Clough, S. A.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Doherty, R. W.

D. F. Flanigan, R. W. Doherty, A. C. Samuels, Infrared Absorptivity of Bacillus Subtilis (BG) and Several Battlefield Aerosols, Rep. ECBC-TR-118 (Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Md., 2000).

Flanigan, D. F.

D. F. Flanigan, “Hazardous cloud imaging: a new way of using passive infrared,” Appl. Opt. 36, 7027–7036 (1997).
[CrossRef]

D. F. Flanigan, R. W. Doherty, A. C. Samuels, Infrared Absorptivity of Bacillus Subtilis (BG) and Several Battlefield Aerosols, Rep. ECBC-TR-118 (Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Md., 2000).

Gillespie, P. S.

Hall, L. A.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Kneizys, F. X.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Laufer, G.

Ligon, D. A.

Luo, S.

S. Luo, D. O. Anderson, A. J. Mohr, Abbreviated Test Plan for Technology Readiness Evaluation for Biological Standoff Detection System, Dugway Proving Ground Document WDTC-TP-02-026 (West Desert Test Center, U.S. Army Dugway Proving Ground, Dugway, Utah, June 2002).

Marshall, T. L.

C. T. Chaffin, T. L. Marshall, N. C. Chaffin, “Passive FT-IR remote sensing of smokestack emissions,” Field Anal. Chem. Technol. 3, 111–115 (1999).
[CrossRef]

Mohr, A. J.

S. Luo, D. O. Anderson, A. J. Mohr, Abbreviated Test Plan for Technology Readiness Evaluation for Biological Standoff Detection System, Dugway Proving Ground Document WDTC-TP-02-026 (West Desert Test Center, U.S. Army Dugway Proving Ground, Dugway, Utah, June 2002).

Samuels, A. C.

D. F. Flanigan, R. W. Doherty, A. C. Samuels, Infrared Absorptivity of Bacillus Subtilis (BG) and Several Battlefield Aerosols, Rep. ECBC-TR-118 (Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Md., 2000).

Shettle, E. P.

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

Thériault, J.-M.

J.-M. Thériault, “Modeling the responsivity and self-emission of a double-beam Fourier-transform infrared interferometer,” Appl. Opt. 38, 505–515 (1999).
[CrossRef]

J.-M. Thériault, Passive Standoff Detection of Chemical Vapors by Differential FTIR Radiometry, Defence Research Establishment Valcartier Technical Report TR-2000-156 (Defence Research and Development Canada—Valcartier, Val-Belair, Quebec, Canada, 2001).

Wetmore, A. E.

Appl. Opt.

Field Anal. Chem. Technol.

C. T. Chaffin, T. L. Marshall, N. C. Chaffin, “Passive FT-IR remote sensing of smokestack emissions,” Field Anal. Chem. Technol. 3, 111–115 (1999).
[CrossRef]

Opt. Express

Other

S. Luo, D. O. Anderson, A. J. Mohr, Abbreviated Test Plan for Technology Readiness Evaluation for Biological Standoff Detection System, Dugway Proving Ground Document WDTC-TP-02-026 (West Desert Test Center, U.S. Army Dugway Proving Ground, Dugway, Utah, June 2002).

S. A. Clough, F. X. Kneizys, G. P. Anderson, E. P. Shettle, J. H. Chetwynd, L. W. Abreu, L. A. Hall, “FASCD3P: spectral simulation,” in IRS ’88: Current Problems in Atmospheric Radiation, J. Lenoble, J. F. Geleyn, eds. (A. Deepak, Hampton, Va., 1988), pp. 372–375.

J.-M. Thériault, Passive Standoff Detection of Chemical Vapors by Differential FTIR Radiometry, Defence Research Establishment Valcartier Technical Report TR-2000-156 (Defence Research and Development Canada—Valcartier, Val-Belair, Quebec, Canada, 2001).

D. F. Flanigan, R. W. Doherty, A. C. Samuels, Infrared Absorptivity of Bacillus Subtilis (BG) and Several Battlefield Aerosols, Rep. ECBC-TR-118 (Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Md., 2000).

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Figures (12)

Fig. 1
Fig. 1

(a) Photograph, (b) optical configuration, and (c) corresponding FOV scenes of the CATSI with the 25-cm telescope configuration for the TRE trial.

Fig. 2
Fig. 2

Display screen of the GASEM monitoring algorithm taken during the excursion phase of the DPG TRE trial, held 15–26 July 2002. The four windows on the left portion of the display represent the time evolution of the cloud and fitted parameters, while the right portion corresponds to real-time measured and fitted spectra, and the corresponding residual.

Fig. 3
Fig. 3

Spectral absorption coefficient of BG used for the detection analysis.9

Fig. 4
Fig. 4

(a) Example of a spectral measurement of a BG cloud made at a distance of ∼3 km together with the corresponding GASEM best-fit spectrum. The measured spectrum is a sample extracted from the data set of the BG puff release episode of 23 July 2002, starting time 00:13:01(LT). The bottom curve corresponds to a measured spectrum without BG, i.e., recorded prior to the BG release. (b) Correlation factor (r 2) recorded during the BG puff release episode of 23 July 2002, starting time 00:13:01(LT). High r 2 values indicate the presence of BG.

Fig. 5
Fig. 5

BG particle densities as measured by the XM-94 lidar at 00:22:51 (LT), 23 July 2002, which correspond to the CATSI measurement shown in Fig. 4(a).

Fig. 6
Fig. 6

Brightness temperature of the clear scene background (T clear) compared with the temperature of the cloud for the corresponding spectral measurement of 23 July 2002, 00:22:54 (LT) (see Fig. 4).

Fig. 7
Fig. 7

Comparison of the main factors contributing to the spectrum of BG observed in the field. (a), Radiative contrast between the cloud and the background; (b), pure BG cloud absorption; and (c), resulting spectral radiance of BG in the field.

Fig. 8
Fig. 8

(a) Brightness temperature of the clear scene background radiance (T clear) and the cloud corresponding to the acquisition episode of 26 July 2002, with a starting acquisition time 01:44:12. (b) Screen display summarizing the monitoring result obtained at the acquisition time 01:54:24 for a BG cloud observed at a distance of approximately 3 km.

Fig. 9
Fig. 9

(a) Brightness temperature of the clear scene background radiance (T clear) and the cloud corresponding to the acquisition episode of 26 July 2002, starting acquisition time 01:18:51(LT). (b) Screen display summarizing the monitoring result obtained at the acquisition time 01:54:24(LT) for a BG cloud and an SF6 vapour observed at a distance of approximately 3 km.

Fig. 10
Fig. 10

BG particle densities as measured by the XM-94 lidar at 01:36:00 (LT), 26 July 2002, which corresponds to the FTIR measurement shown in Fig. 9(b). kppl, 1000 particles per liter.

Fig. 11
Fig. 11

FASCODE simulation of a BG detection scenario for a sensor at an altitude of 1 km looking down at an angle of 45°. (a), Corresponding brightness temperatures of the clear scene background radiance (T clear) and the BG cloud; (b), simulated differential radiance computed for this scenario. Note the strength of the BG signal.

Fig. 12
Fig. 12

FASCODE simulation of a BG detection scenario for a sensor looking above the horizon at an elevation angle of 10°. (a), Corresponding brightness temperatures of the clear scene background radiance (T clear) and the cloud indicate a radiative contrast of approximately 40 K; (b), simulated differential radiance computed for this scenario. Note the strength of the signal and also the shape similarity with the spectrum measured at the trial [i.e., Fig. 4(a) and others].

Equations (6)

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L1-L2δLcloud= 1-τcloudBcloud-Lclear,
τcloud=exp-ανcl,
δLcloud= 1-τcloudΔBcloud-Lclear,
τcloudΔ=exp-ανΔcl
minνminνmaxδLcloud+O- δLmeas2.
r2=i=1nchanfi-f¯yi-y¯2i=1nchanfi-f¯2i=1nchanyi-y¯2,

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