3.7.1. CL31¶
3.7.1.1. Introduction¶
The CL31 is a ceilometer manufactured by Vaisala. They measure the atmospheric backscatter and can determine cloud heights for multiple layers. Ceilometers work with an invisible eye safe laser that shoots directly upwards into the air. The CL31 is a newer version than the CT25K and gives slightly better results.
3.7.1.2. Manufacturer and Model¶
Model |
Brand |
Type |
|---|---|---|
CL31 |
Vaisala |
Ceilometer |
3.7.1.3. Output definitions¶
Ouput definition ID |
File Identifier |
Level Number |
QAQC notes |
File time resolution |
|---|---|---|---|---|
CL31_BSC |
CL31-%LETTER_BSC_%SITE |
0 |
3sec |
|
CL31_BSC |
CL31-%LETTER_BSC_%SITE |
1 |
15sec |
|
CL31_CLD |
CL31-%LETTER_CLD_%SITE |
0 |
15sec |
|
CL31_CCW30 |
CL31-%LETTER_CCW30_%SITE |
1 |
15min |
|
CL31_MLH |
CL31-%LETTER_MLH_%SITE |
1 |
15min |
3.7.1.4. Processing code¶
Code used to process raw data: https://github.com/Urban-Meteorology-Reading/Operations-CEIL
3.7.1.5. Variables measured by instrument¶
Variable ID |
Full Name |
Unit |
Lower Threshold |
Upper Threshold |
Files present (Output definition ID,Level No,Time resolution) |
|---|---|---|---|---|---|
beta |
height normalised backscatter |
10-8.m-1.sr-1 |
CL31_BSC,1,15sec |
||
beta_tR |
smoothed backscatter in height and time |
10-8.m-1.sr-1 |
CL31_BSC,1,15sec |
||
BG_light |
background light |
mV |
0.0 |
CL31_CLD,0,15sec |
|
BSC |
height normalised backscatter |
10-8.m-1.sr-1 |
CL31_BSC,0,3sec |
||
BSC_sum |
sum of detected normalised backscatter |
10-8.m-1.sr-1 |
CL31_CLD,0,15sec |
||
CBH |
Cloud Base Height |
m |
0.0 |
CL31_CCW30,1,15min |
|
CC_high |
high cloud amount |
% |
0.0 |
100.0 |
CL31_CCW30,1,15min |
CC_low |
low cloud amount |
% |
0.0 |
100.0 |
CL31_CCW30,1,15min |
CC_medium |
medium cloud amount |
% |
0.0 |
100.0 |
CL31_CCW30,1,15min |
CLD_Cover_sc_L1 |
cloud cover sky condition level 1 |
oktas |
0.0 |
8.0 |
CL31_CLD,0,15sec |
CLD_Cover_sc_L2 |
cloud cover sky condition level 2 |
oktas |
0.0 |
8.0 |
CL31_CLD,0,15sec |
CLD_Cover_sc_L3 |
cloud cover sky condition level 3 |
oktas |
0.0 |
8.0 |
CL31_CLD,0,15sec |
CLD_Cover_sc_L4 |
cloud cover sky condition level 4 |
oktas |
0.0 |
8.0 |
CL31_CLD,0,15sec |
CLD_Cover_sc_L5 |
cloud cover sky condition level 5 |
oktas |
0.0 |
8.0 |
CL31_CLD,0,15sec |
CLD_Height_L1 |
cloud height level 1 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_L2 |
cloud height level 2 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_L3 |
cloud height level 3 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_sc_L1 |
cloud height sky condition level 1 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_sc_L2 |
cloud height sky condition level 2 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_sc_L3 |
cloud height sky condition level 3 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_sc_L4 |
cloud height sky condition level 4 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_Height_sc_L5 |
cloud height sky condition level 5 |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
|
CLD_status |
cloud_detection_status |
dimensionless |
CL31_CLD,0,15sec |
||
clear |
Percentage of clear sky within time frame |
% |
0.0 |
100.0 |
CL31_CCW30,1,15min |
LH_L1 |
Layer 1 height |
m a.s.l. |
CL31_MLH,1,15min |
||
LH_L2 |
Layer 2 height |
m a.s.l. |
CL31_MLH,1,15min |
||
LH_L3 |
Layer 3 height |
m a.s.l. |
CL31_MLH,1,15min |
||
LH_L4 |
Layer 4 height |
m a.s.l. |
CL31_MLH,1,15min |
||
LH_L5 |
Layer 5 height |
m a.s.l. |
CL31_MLH,1,15min |
||
LH_L6 |
Layer 6 height |
m a.s.l. |
CL31_MLH,1,15min |
||
MH |
Mixing height |
m |
CL31_MLH,1,15min |
||
nSamples |
nSamples |
samples/interval |
CL31_CCW30,1,15min |
||
pulse |
laser pulse energy |
% |
0.0 |
CL31_CLD,0,15sec CL31_CCW30,1,15min |
|
rain |
Rain CL31 |
% |
CL31_MLH,1,15min |
||
sd_LH_L1 |
Standard deviation layer 1 height |
m |
CL31_MLH,1,15min |
||
sd_LH_L2 |
Standard deviation layer 2 height |
m |
CL31_MLH,1,15min |
||
sd_LH_L3 |
Standard deviation layer 3 height |
m |
CL31_MLH,1,15min |
||
sd_LH_L4 |
Standard deviation layer 4 height |
m |
CL31_MLH,1,15min |
||
sd_LH_L5 |
Standard deviation layer 5 height |
m |
CL31_MLH,1,15min |
||
sd_LH_L6 |
Standard deviation layer 6 height |
m |
CL31_MLH,1,15min |
||
sd_MLH |
Standard deviation mixing height |
m |
CL31_MLH,1,15min |
||
SNR |
Signal to Noise Ratio |
dimensionless |
CL31_BSC,1,15sec |
||
tilt |
tilt angle |
degree |
CL31_CLD,0,15sec CL31_CCW30,1,15min |
||
Tlaser |
laser temperature |
Celsius |
CL31_CLD,0,15sec CL31_CCW30,1,15min |
||
transmission |
window transmission |
% |
0.0 |
CL31_CLD,0,15sec CL31_CCW30,1,15min |
|
vis_z |
vertical_visibility |
m a.s.l. |
CL31_CLD,0,15sec CL31_CCW30,1,15min |
||
vis_z_max |
maximum visibility |
m a.s.l. |
0.0 |
CL31_CLD,0,15sec |
3.7.1.6. Serials¶
Serial |
Suffix |
|---|---|
A |
|
B |
|
C |
|
D |
|
E |
|
F |
|
G |
3.7.1.7. Deployments¶
3.7.1.7.1. Serial number: F2730002¶
Site ID |
Start date |
End date |
|---|---|---|
2010-09-21 00:00 |
2011-03-02 00:00 |
|
2011-03-09 00:00 |
3.7.1.7.2. Serial number: WMO03672¶
Site ID |
Start date |
End date |
|---|---|---|
2016-10-06 00:00 |
2017-09-18 00:00 |
3.7.1.7.3. Serial number: 103150004¶
Site ID |
Start date |
End date |
|---|---|---|
2010-10-02 00:00 |
2012-09-12 00:00 |
|
2016-07-07 00:00 |
2018-11-14 00:00 |
|
2018-12-12 00:00 |
3.7.1.7.4. Serial number: B20202¶
Site ID |
Start date |
End date |
|---|---|---|
2007-12-04 00:00 |
2008-08-20 00:00 |
|
2009-03-26 00:00 |
2016-06-14 00:00 |
|
2016-06-26 00:00 |
2020-03-17 00:00 |
3.7.1.7.5. Serial number: J1720003¶
Site ID |
Start date |
End date |
|---|---|---|
2014-04-23 00:00 |
3.7.1.7.6. Serial number: B20201¶
Site ID |
Start date |
End date |
|---|---|---|
2006-11-29 00:00 |
2009-04-22 00:00 |
|
2009-04-22 00:00 |
2011-12-31 00:00 |
|
2012-01-01 00:00 |
2016-04-14 00:00 |
|
2016-04-29 00:00 |
2019-12-18 00:00 |
|
2020-02-06 00:00 |
2021-07-15 00:00 |
|
2021-07-15 00:00 |
3.7.1.7.7. Serial number: F2730001¶
Site ID |
Start date |
End date |
|---|---|---|
2010-09-23 00:00 |
2011-01-07 00:00 |
|
2011-01-19 00:00 |
2011-02-02 00:00 |
|
2011-02-02 00:00 |
2016-07-07 00:00 |
|
2016-11-04 00:00 |
2017-06-25 00:00 |
|
2017-11-10 00:00 |
2020-02-18 00:00 |
3.7.1.8. Photos¶
3.7.1.9. Supplementary information¶
Link |
Title |
Description |
|---|---|---|
https://www.manualslib.com/manual/1226537/Vaisala-Cl31.html#manual |
CL31 user guide |
Manual provided by Vaisala. If link has expired please raise a GitHub Issues. |
3.7.1.10. Data acquisition¶
Data can be requested from Prof. Sue Grimmond (c.s.grimmond@reading.ac.uk).
3.7.1.11. References¶
Warren, E., Charlton‐Perez, C., Lean, H., Kotthaus, S. and Grimmond, S. (2022) Spatial variability of forward modelled attenuated backscatter in clear‐sky conditions over a megacity: implications for observation network design. Quarterly Journal of the Royal Meteorological Society. ISSN 0035-9009 doi: https://doi.org/10.1002/qj.4253 (In Press)
Wang, W., Shao, L., Mazzoleni, C., Li, Y., Kotthaus, S., Grimmond, S., Bhandari, J., Xing, J., Feng, X., Zhang, M. and Shi, Z. (2021) Measurement report: comparison of wintertime individual particles at ground level and above the mixed layer in urban Beijing. Atmospheric Chemistry and Physics, 21 (7). pp. 5301-5314. ISSN 1680-7316 doi: https://doi.org/10.5194/acp-21-5301-2021
Joshi, R., Liu, D., Nemitz, E., Langford, B., Mullinger, N., Squires, F., Lee, J., Wu, Y., Pan, X., Fu, P., Kotthaus, S., Grimmond, S., Zhang, Q., Wu, R., Wild, O., Flynn, M., Coe, H. and Allan, J. (2021) Direct measurements of black carbon fluxes in central Beijing using the eddy covariance method. Atmospheric Chemistry and Physics, 21 (1). pp. 147-162. ISSN 1680-7324 doi: https://doi.org/10.5194/acp-21-147-2021
Sützl, B. S., Rooney, G. G., Finnenkoetter, A., Bohnenstengel, S. I., Grimmond, C. S. B. and Reeuwijk, M. v. (2021) Distributed urban drag parameterization for sub‐kilometre scale numerical weather prediction. Quarterly Journal of the Royal Meteorological Society. ISSN 1477-870X doi: https://doi.org/10.1002/qj.4162
Kotthaus, S., Haeffelin, M., Drouin, M.-A., Dupont, J.-C., Grimmond, S., Haefele, A., Hervo, M., Poltera, Y. and Wiegner, M. (2020) Tailored algorithms for the detection of the atmospheric boundary layer height from common automatic lidars and ceilometers (ALC). Remote Sensing, 12 (19). p. 3259. ISSN 2072-4292 doi: https://doi.org/10.3390/rs12193259
Hertwig, D., Grimmond, S., Kotthaus, S., Vanderwel, C., Gough, H., Haeffelin, M. and Robins, A. (2020) Variability of physical meteorology in urban areas at different scales: implications for air quality. Faraday Discussions. ISSN 1364-5498 doi: https://doi.org/10.1039/D0FD00098A
Squires, F. A., Nemitz, E., Langford, B., Wild, O., Drysdale, W. S., Acton, W. J. F., Fu, P., Grimmond, C. S. B., Hamilton, J. F., Hewitt, C. N., Hollaway, M., Kotthaus, S., Lee, J., Metzger, S., Pingintha-Durden, N., Shaw, M., Vaughan, A. R., Wang, X., Wu, R., Zhang, Q. and Zhang, Y. (2020) Measurements of traffic-dominated pollutant emissions in a Chinese megacity. Atmospheric Chemistry and Physics, 20 (14). pp. 8737-8761. ISSN 1680-7316 doi: https://doi.org/10.5194/acp-20-8737-2020
Harrison, R. M., Beddows, D. C. S., Alam, M. S., Singh, A., Brean, J., Xu, R., Kotthaus, S. and Grimmond, S. (2019) Interpretation of particle number size distributions measured across an urban area during the FASTER campaign. Atmospheric Chemistry and Physics, 19 (1). pp. 39-55. ISSN 1680-7324 doi: https://doi.org/10.5194/acp-19-39-2019
Shi, Z., Vu, T., Kotthaus, S., Harrison, R. M., Grimmond, S., Yue, S., Zhu, T., Lee, J., Han, Y., Demuzere, M., Dunmore, R. E., Ren, L., Liu, D., Wang, Y., Wild, O., Allan, J., Acton, W. J., Barlow, J., Barratt, B., Beddows, D., Bloss, W. J., Calzolai, G., Carruthers, D., Carslaw, D. C., Chan, Q., Chatzidiakou, L., Chen, Y., Crilley, L., Coe, H., Dai, T., Doherty, R., Duan, F., Fu, P., Ge, B., Ge, M., Guan, D., Hamilton, J. F., He, K., Heal, M., Heard, D., Hewitt, C. N., Hollaway, M., Hu, M., Ji, D., Jiang, X., Jones, R., Kalberer, M., Kelly, F. J., Kramer, L., Langford, B., Lin, C., Lewis, A. C., Li, J., Li, W., Liu, H., Liu, J., Loh, M., Lu, K., Lucarelli, F., Mann, G., McFiggans, G., Miller, M. R., Mills, G., Monk, P., Nemitz, E., O'Connor, F., Ouyang, B., Palmer, P. I., Percival, C., Popoola, O., Reeves, C., Rickard, A. R., Shao, L., Shi, G., Spracklen, D., Stevenson, D., Sun, Y., Sun, Z., Tao, S., Tong, S., Wang, Q., Wang, W., Wang, X., Wang, X., Wang, Z., Wei, L., Whalley, L., Wu, X., Wu, Z., Xie, P., Yang, F., Zhang, Q., Zhang, Y., Zhang, Y. and Zheng, M. (2019) In-depth study of air pollution sources and processes within Beijing and its surrounding region (APHH-Beijing). Atmospheric Chemistry and Physics (11). pp. 7519-7546. ISSN 1680-7316 doi: https://doi.org/10.5194/acp-19-7519-2019
Theeuwes, N. E., Barlow, J. F., Teuling, A. J., Grimmond, C. S. B. and Kotthaus, S. (2019) Persistent cloud cover over mega-cities linked to surface heat release. npj Climate and Atmospheric Science, 2. 15. ISSN 2397-3722 doi: https://doi.org/10.1038/s41612-019-0072-x
Kotthaus, S. and Grimmond, C. S. B. (2018) Atmospheric boundary layer characteristics from ceilometer measurements. Part 1: a new method to track mixed layer height and classify clouds. Quarterly Journal of the Royal Meteorological Society, 144 (714). pp. 1525-1538. ISSN 1477-870X doi: https://doi.org/10.1002/qj.3299
Kent, C. W., Grimmond, C. S. B., Gatey, D. and Barlow, J. F. (2018) Assessing methods to extrapolate the vertical wind-speed profile from surface observations in a city centre during strong winds. Journal of Wind Engineering and Industrial Aerodynamics, 173. pp. 100-111. ISSN 0167-6105 doi: https://doi.org/10.1016/j.jweia.2017.09.007
Kotthaus, S., Halios, C. H., Barlow, J. F. and Grimmond, C. S. B. (2018) Volume for pollution dispersion: London’s atmospheric boundary layer during ClearfLo observed with two ground-based lidar types. Atmospheric Environment, 190. pp. 401-414. ISSN 1352-2310 doi: https://doi.org/10.1016/j.atmosenv.2018.06.042
Kotthaus, S. and Grimmond, C. S. B. (2018) Atmospheric boundary layer characteristics from Ceilometer measurements part 2: application to London’s urban boundary layer. Quarterly Journal of the Royal Meteorological Society, 144 (714). pp. 1511-1524. ISSN 1477-870X doi: https://doi.org/10.1002/qj.3298
Peng, J., Grimmond, C. S. B., Fu, X. S., Chang, Y. Y., Zhang, G., Guo, J., Tang, C. Y., Gao, J., Xu, X. D. and Tan, J. G. (2017) Ceilometer based analysis of Shanghai’s boundary layer height (under rain and fog free conditions). Journal of Atmospheric and Oceanic Technology, 34 (4). pp. 749-764. ISSN 1520-0426 doi: https://doi.org/10.1175/JTECH-D-16-0132.1
Kotthaus, S., O’Connor, E., M�nkel, C., Charlton-Perez, C., Haeffelin, M., Gabey, A. M. and Grimmond, C. S. B. (2016) Recommendations for processing atmospheric attenuated backscatter profiles from Vaisala CL31 ceilometers. Atmospheric Measurement Techniques, 9. pp. 3769-3791. ISSN 1867-8548 doi: https://doi.org/10.5194/amt-9-3769-2016
Tan, J., Yang, L., Grimmond, C. S. B., Shi, J., Gu, W., Chang, Y., Hu, P., Sun, J., Ao, X. and Han, Z. (2015) Urban integrated meteorological observations: practice and experience in Shanghai, China. Bulletin of the American Meteorological Society, 96 (1). pp. 85-102. ISSN 0003-0007 doi: https://doi.org/10.1175/BAMS-D-13-00216.1
Kotthaus, S. and Grimmond, C. S. B. (2014) Energy exchange in a dense urban environment – part I: temporal variability of long-term observations in central London. Urban Climate, 10 (2). pp. 261-280. ISSN 2212-0955 doi: https://doi.org/10.1016/j.uclim.2013.10.002
Magliulo, V., Toscano, P., Grimmond, C. S. B., Kotthaus, S., J�rvi, L., Set�l�, H., Lindberg, F., Vogt, R., Staszewski, T., Bubak, A., Synnefa, A. and Santamouris, M. (2014) Environmental measurements in BRIDGE case studies. In: Chrysoulakis, N., de Castro, E. A. and Moors, E. J. (eds.) Understanding Urban Metabolism. Routledge, pp. 45-57. ISBN 9780415835114
Oliphant, A.J., Dragoni, D., Deng, B., Grimmond, C.S.B., Schmid, H.-P. and Scott, S.L. (2011) The role of sky conditions on gross primary production in a mixed deciduous forest. Agricultural and Forest Meteorology, 151 (7). pp. 781-791. ISSN 0168-1923 doi: https://doi.org/10.1016/j.agrformet.2011.01.005
Loridan, T., Grimmond, C.S.B., Offerle, B. D., Young, D. T., Smith, T. E. L., J�rvi, L. and Lindberg, F. (2011) Local-scale urban meteorological parameterization scheme (LUMPS): longwave radiation parameterization and seasonality-related developments. Journal of Applied Meteorology and Climatology, 50 (1). pp. 185-202. ISSN 1558-8424 doi: https://doi.org/10.1175/2010JAMC2474.1
Tip
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