Wet-Bulb Globe Temperature Data Report

Transcription

1 ARL-SR-0317 MAR 2015 US Army Research Laboratory Wet-Bulb Globe Temperature Data Report by David P Sauter

2 Approved for public release; distribution unlimited

3 NOTICES Disclaimers The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. Citation of manufacturer s or trade names does not constitute an official endorsement or approval of the use thereof. Destroy this report when it is no longer needed. Do not return it to the originator.

4 ARL-SR-0317 MAR 2015 US Army Research Laboratory Wet-Bulb Globe Temperature Data Report by David P Sauter Computational and Information Sciences Directorate, ARL Approved for public release; distribution unlimited. FOR OFFICIAL USE ONLY (delete if not FOUO)

5 REPORT DOCUMENTATION PAGE Form Approved OMB No Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports ( ), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-Mar MM-YYYY) March REPORT TYPE Special Report 4. TITLE AND SUBTITLE Wet-Bulb Globe Temperature Data Report 3. DATES COVERED (From - To) 11 Aug Aug a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) David P Sauter 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army Research Laboratory ATTN: RDRL-CIE-D White Sands Missile Range, NM PERFORMING ORGANIZATION REPORT NUMBER ARL-SR SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) 11. SPONSOR/MONITOR'S REPORT NUMBER(S) 12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release; distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Wet-Bulb Globe Temperature (WBGT) is used extensively by the US military (and others) to provide guidance for work and rest periods as well as water intake by Soldiers in a hot environment. In an effort to help validate a predictive WBGT algorithm in use in a heat-stress-guidance application, WBGT data measurements were performed at Eglin Air Force Base, Florida, in August The data and a brief data analysis are included in this report. 15. SUBJECT TERMS Wet-Bulb Globe Temperature, heat stress 16. SECURITY CLASSIFICATION OF: a. REPORT Unclassified b. ABSTRACT Unclassified c. THIS PAGE Unclassified 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 19 19a. NAME OF RESPONSIBLE PERSON David P Sauter 19b. TELEPHONE NUMBER (Include area code) (575) Standard Form 298 (Rev. 8/98) Prescribed by ANSI Std. Z39.18 ii

6 Contents List of Figures List of Tables Acknowledgments iv iv v 1. Introduction 1 2. Instrumentation and Site Overview 1 3. Data Analysis 3 4. Data 4 5. References 10 Distribution List 11 iii

7 List of Figures Fig. 1 3M QUESTemp 32 Sensor... 1 Fig. 2 Sigma Products tactical WBGT kit... 2 Fig. 3 Kestrel 4400 Heat Stress Tracker... 2 Fig. 4 Eglin AFB s WBGT data-collection site... 3 List of Tables Table 1a WBGT and Meteorological Data for Quest, Sigma 1 (S1), and Kestrel 2 (K2) Sensors... 5 Table 1b WBGT and Meteorological Data for Quest, Sigma 1 (S1), and Kestrel 2 (K2) Sensors... 6 Table 1c WBGT and Meteorological Data for Quest, Sigma 1 (S1), and Kestrel 2 (K2) Sensors... 7 Table 2a WBGT and Meteorological Data for Quest, Sigma 2 (S2), and Kestrel 1 (K1) Sensors... 8 Table 2b WBGT and Meteorological Data for Quest, Sigma 2(S2), and Kestrel 1 (K1) Sensors... 9 iv

8 Acknowledgments The author would like to acknowledge the 96 th Weather Flight at Eglin Air Force Base, Florida, for its outstanding support before, during, and after the datacollection effort. Special thanks go to Mr. David Biggar, staff meteorologist with the 96 th. v

9 1. Introduction The Wet-Bulb Globe Temperature (WBGT) is used extensively by the US military (and others) to provide guidance for work and rest periods as well as water intake by Soldiers in a hot environment. In an effort to validate a predictive WBGT algorithm within a heat-stress-guidance application, WBGT-data measurements were performed at Eglin Air Force Base (AFB), Florida, in August A recent paper (Sauter 2013) provides details of the heat-stress-guidance application and the role of the WBGT. This report includes an overview of the instrumentation and site, the actual data, and a brief analysis of the data. The primary intent is to make the data available (an Excel spreadsheet of the data is available upon request). 2. Instrumentation and Site Overview The WBGT consists of 3 separate temperature components (Sauter 2013): Ambient dry-bulb temperature (T d ) Natural wet-bulb temperature (T w ) Black-globe temperature (T g ) These values are typically measured directly as with the 3M QUESTemp QT32 sensor (Fig. 1) or the Sigma Products tactical WBGT kit (Fig. 2). Fig. 1 3M QUESTemp 32 Sensor 1

10 Fig. 2 Sigma Products tactical WBGT kit In the case of the Kestrel 4400 Heat Stress Tracker (Fig. 3), the natural wet-bulb component of the WBGT is computed as a function of the measured ambient temperature and humidity values. Fig. 3 Kestrel 4400 Heat Stress Tracker One each of the QT32, Sigma, and Kestrel sensors was used simultaneously in the data-collection process. Two each of the Sigma Products kits and the Kestrel 4400 meters were available and were interchanged approximately halfway through the data-collection period. 2

11 Data collection was conducted at Eglin AFB in a grassy and somewhat open area (Fig. 4). August was chosen in order to collect data in a hot and humid environment that lends itself to relatively high WBGT values and conditions favorable for heatstress injuries. As the QT32 instrument is not designed to be exposed to precipitation, there are no observations for rainy conditions. Readings were generally taken every 30 min between mid-morning and late afternoon. A sampling duration of 60 s was chosen. The Kestrel 4400 sensor is able to automatically take samples every 2 s over the minute period and then display the average WBGT component values. For the Sigma WBGT kit and the QT32 sensor, the readings were taken immediately after the Kestrel readings were initiated and then again immediately after they were concluded. These values were then simply summed and halved to provide the average. 3. Data Analysis Fig. 4 Eglin AFB s WBGT data-collection site Although not intended to be a complete and detailed analysis of the data, the following observations have been made regarding the measurements from the various instruments, some of which belonged to the US Army Research Laboratory (ARL) and some to the 96 th Weather Flight. 1) Compared to the QT32 and Sigma instruments, the Kestrel 4400 Heat Stress Meter s derived T w values are too high (4 6 F or more) under conditions with significant, direct solar load on the instrument. The Nielsen Kellerman Co. (manufacturer of the Kestrels) was contacted regarding this bias (Sauter 3

12 2014a) and modifications to the software that computes the T w were made. Subsequent measurements will be made once the updated sensor is received. 2) Under conditions of high solar load and light wind speeds, the Sigma Products T d values typically exhibited an 8 10 F warm bias as compared to the QT32 and Kestrel devices (as well as to a National Weather Service measuring site located less than a mile away). This information was provided to a Sigma Products representative (Sauter 2014b). As a result, the author was provided 2 additional tactical WBGT kits that were painted white (one matte and the other glossy) instead of the dark green of the original sensor. Limited follow-on measurements with the white sensors indicated somewhat lower T d readings, but still higher than expected. Additional observations are anticipated later in ) Although the relative-humidity (RH) value is not used by the QT32 sensor in the computation of the WBGT, the value exhibits a significantly low bias (20% or more) under hot and sunny conditions. It is believed that this is due to the RH sensor being located inside the QT32 housing and not being adequately ventilated. This was reported to a 3M (manufacturer of the QUESTemp sensors) representative (Sauter 2014c) who concurred with the finding. While at Eglin AFB, several readings from a second QT32 sensor (property of the 96 th Weather Flight) were compared to the ARL s QT32 and provided nearly identical results. The QT32 sensor readings are considered the baseline values. 4. Data The raw data from the Eglin AFB site are included in the following tables. Tables 1a 1c include the observations for Sigma sensor 1 and Kestrel sensor 2 while Tables 2a 2b include Sigma sensor-2 and Kestrel sensor-1 observations. An Excel spreadsheet of the data is available from the author upon request. 4

13 5 Table 1a WBGT and Meteorological Data for Quest, Sigma 1 (S1), and Kestrel 2 (K2) Sensors SIGMA 1 QUEST KESTREL 2 Mon Day Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPS c RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F deg F deg F deg F deg F deg F deg F deg F deg F mph tenths code a code b % % % deg F deg F deg F Notes: All observations were taken at N, W (Eglin AFB). Local time = GMT 5 h. a 0 = none; 1 = stratocumulus; 2 = cumulus; 3 = altostratus/altocumulus; 5 = thin cirrus; 6 = thick cirrus; 7 = precipitation. b 0 = sun not obscured; 1 = sun partially obscured; 2 = sun obscured. c National Weather Service observation site at the Northwest Florida Regional Airport (Valparaiso), less than 1 mile south southwest of the WBGT observation site.

14 6 Table 1b WBGT and Meteorological Data for Quest, Sigma 1 (S1), and Kestrel 2 (K2) Sensors SIGMA 1 QUEST KESTREL 2 Mon Day Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPS c RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F deg F deg F deg F deg F deg F deg F deg F deg F mph tenths code a code b % % % deg F deg F deg F Notes: All observations were taken at N, W (Eglin AFB). Local time = GMT 5 h. a 0 = none; 1 = stratocumulus; 2 = cumulus; 3 = altostratus/altocumulus; 5 = thin cirrus; 6 = thick cirrus; 7 = precipitation. b 0 = sun not obscured; 1 = sun partially obscured; 2 = sun obscured. c National Weather Service observation site at the Northwest Florida Regional Airport (Valparaiso), less than 1 mile south southwest of the WBGT observation site.

15 7 Table 1c WBGT and Meteorological Data for Quest, Sigma 1 (S1), and Kestrel 2 (K2) Sensors SIGMA 1 QUEST KESTREL 2 Mon Day Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPS c RH S1 WBGT Q WBGT K2 WBGT GMT millibars deg F deg F deg F deg F deg F deg F deg F deg F deg F mph tenths code a code b % % % deg F deg F deg F Notes: All observations were taken at N, W (Eglin AFB). Local time = GMT 5 h. a 0 = none; 1 = stratocumulus; 2 = cumulus; 3 = altostratus/altocumulus; 5 = thin cirrus; 6 = thick cirrus; 7 = precipitation. b 0 = sun not obscured; 1 = sun partially obscured; 2 = sun obscured. c National Weather Service observation site at the Northwest Florida Regional Airport (Valparaiso), less than 1 mile south southwest of the WBGT observation site.

16 8 Table 2a WBGT and Meteorological Data for Quest, Sigma 2 (S2), and Kestrel 1 (K1) Sensors SIGMA 2 QUEST KESTREL 1 Mon Day Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPS c RH S2 WBGT Q WBGT K1 WBGT GMT millibars deg F deg F deg F deg F deg F deg F deg F deg F deg F mph tenths code a code b % % % deg F deg F deg F Notes: All observations were taken at N, W (Eglin AFB). Local time = GMT 5 h. a 0 = none; 1 = stratocumulus; 2 = cumulus; 3 = altostratus/altocumulus; 5 = thin cirrus; 6 = thick cirrus; 7 = precipitation. b 0 = sun not obscured; 1 = sun partially obscured; 2 = sun obscured. c National Weather Service observation site at the Northwest Florida Regional Airport (Valparaiso), less than 1 mile south southwest of the WBGT observation site.

17 9 Table 2b WBGT and Meteorological Data for Quest, Sigma 2(S2), and Kestrel 1 (K1) Sensors SIGMA 2 QUEST KESTREL 1 Mon Day Hour Min Pressure Dry Nat Wet Globe Dry Nat Wet Globe Dry Nat Wet Globe Wind Cld amt Cld type Obscuration Quest RH Kestrel RH VPS c RH S2 WBGT Q WBGT K1 WBGT GMT millibars deg F deg F deg F deg F deg F deg F deg F deg F deg F mph tenths code a code b % % % deg F deg F deg F Notes: All observations were taken at N, W (Eglin AFB). Local time = GMT 5 h. a 0 = none; 1 = stratocumulus; 2 = cumulus; 3 = altostratus/altocumulus; 5 = thin cirrus; 6 = thick cirrus; 7 = precipitation. b 0 = sun not obscured; 1 = sun partially obscured; 2 = sun obscured. c National Weather Service observation site at the Northwest Florida Regional Airport (Valparaiso), less than 1 mile south southwest of the WBGT observation site.

18 5. References Sauter DP. A wet-bulb globe temperature validation study using standard meteorological inputs and modeled solar irradiance. J Oper Meteor. 2013:1(18): Sauter D. Personal communication (Joe Racosky, Advanced Technical and Customer Support Engineering, the Nielsen Kellerman Co.), 2014a. Sauter D. Personal communication (Matt Cramer, General Manager, Sigma Products), 2014b. Sauter D. Personal communication (Mark E. Scherer, Technical Support Engineer, Detection Portfolio 3M Personal Safety Division, Quest Technologies), 2014c. 10

19 1 DEFENSE TECHNICAL (PDF) INFORMATION CTR DTIC OCA 2 DIRECTOR (PDF) US ARMY RESEARCH LAB RDRL CIO LL IMAL HRA MAIL & RECORDS MGMT 1 GOVT PRINTG OFC (PDF) A MALHOTRA 1 DIRECTOR (PDF) US ARMY RESEARCH LAB 1 DAVID SAUTER (PDF) US ARMY RESEARCH LAB RDRL-CIE-D 11