Korean Journal of Agricultural and Forest Meteorology (한국농림기상학회지)

Korean Society of Agricultural and Forest Meteorology (한국농림기상학회)
권호 표지
DOI QR코드

DOI QR Code

Processing and Quality Control of Flux Data at Gwangneung Forest

광릉 산림의 플럭스 자료 처리와 품질 관리

  • Lim, Hee-Jeong (Department of Astronomy and Atmospheric Sciences, Kyungpook National University) ;
  • Lee, Young-Hee (Department of Astronomy and Atmospheric Sciences, Kyungpook National University)
  • 임희정 (경북대학교 천문대기과학과) ;
  • 이영희 (경북대학교 천문대기과학과)
  • Published : 2008.09.30
Download PDF
⟨ Previous Next ⟩

Abstract

In order to ensure a standardized data analysis of the eddy covariance measurements, Hong and Kim's quality control program has been updated and used to process eddy covariance data measured at two levels on the main flux tower at Gwangneung site from January to May in 2005. The updated program was allowed to remove outliers automatically for $CO_2$ and latent heat fluxes. The flag system consists of four quality groups(G, D, B and M). During the study period, the missing data were about 25% of the total records. About 60% of the good quality data were obtained after the quality control. The number of record in G group was larger at 40m than at 20m. It is due that the level of 20m was within the roughness sublayer where the presence of the canopy influences directly on the character of the turbulence. About 60% of the bad data were due to low wind speed. Energy balance closure at this site was about 40% during the study period. Large imbalance is attributed partly to the combined effects of the neglected heat storage terms, inaccuracy of ground heat flux and advection due to local wind system near the surface. The analysis of wind direction indicates that the frequent occurrence of positive momentum flux was closely associated with mountain valley wind system at this site. The negative $CO_2$ flux at night was examined in terms of averaging time. The results show that when averaging time is larger than 10min, the magnitude of calculated $CO_2$ fluxes increases rapidly, suggesting that the 30min $CO_2$ flux is influenced severely by the mesoscale motion or nonstationarity. A proper choice of averaging time needs to be considered to get accurate turbulent fluxes during nighttime.

보다 자동화된 방법으로 신뢰성 있는 난류 플럭스의 자료를 생산하기 위해서 Hong and Kim(2002)의 난류 품질 관리 프로그램을 개선하고 개선된 프로그램을 광릉산림에 적용하여 복잡한 산림지역에서 난류 플럭스의 특성을 조사하였다. 개선된 프로그램을 이용하여 2005년 1월부터 5월까지 광릉 수목원에 위치한 주 타워의 두 고도(20m와 40m)에서 관측된 난류 자료에 대하여 품질 검사를 실시하였다. 개선전과 비교해 개선된 프로그램은 이상점(outlier)에 해당되는 자료들을 많이 제거하였다. 자료의 품질체계는 4등급(Good, Dubious, Missing, Bad)으로 분류하였으며 본 분석에서 사용된 기간의 자료 중 25%는 결측이었고(Missing 등급), 60%는 Good 등급으로 분류되었다. 고도 별로는 40m에서 관측된 자료가 20m에서 관측된 자료보다 Bad 등급의 자료수가 적었는데 이는 20m가 식생 꼭대기에 인접한 거칠기 아층에 해당하고 또한 풍속도 더 낮은데 기인한다. Bad 등급으로 분류된 자료의 주원인은 낮은 풍속으로 나타났다. 분석 기간 동안의 에너지 수지의 닫힘은 약 40%로 나타났고 이러한 에너지 불균형의 부분적인 이유로는 열 저장항들이 고려되지 않은 점, 토양열 플럭스 측정의 불확실성, 복잡한 지형 등에 의한 국지풍에 의한 이류 등이 복합적으로 작용했을 것으로 생각된다. 광릉에서 발생하는 상향 운동량 플럭스는 국지풍의 발달 시 높은 발생률을 보여 이 둘이 밀접히 관련되어 있음을 나타낸다. 야간에 낮은 음의 $CO_2$ 플럭스가 발생하는 경우에 대하여 평균 시간을 증가시킴에 따른 $CO_2$ flux의 변화를 조사한 결과 평균시간이 10분 이상 증가함에 따라 $CO_2$ flux의 절대값이 빠르게 증가하는 경향을 보였다. 이는 야간에 $CO_2$ 플럭스는 중규모 운동이나 비정상성(nonstationarity) 등의 영향을 많이 받고 있음을 시사한다. 그러므로 야간에 보다 정확한 난류 플럭스 값을 산출하기 위해서는 평균시간의 적절한 조절이 필요할 것으로 보인다.

Keywords

References

  1. Foken, T., and B. Wichura, 1996: Tools for quality assessment of surface-based flux measurements. Agricultural and Forest Meteorology 78, 83-105 https://doi.org/10.1016/0168-1923(95)02248-1
  2. Foken, T., M. Göckede, M. Mauder, L. Mahrt, B. Amiro, and W. Munger, 2004: Post-field data quality control. Handbook of Micrometeorology: A Guide for Surface Flux Measurement and Analysis, X. Lee, W. Massman, and B. Law (Eds.), Kluwer Academic Publishers, 181- 208
  3. Graefe, J., 2004: Roughness layer corrections with emphasis on SVAT model applications. Agricultural and Forest Meteorology 124, 237-271 https://doi.org/10.1016/j.agrformet.2004.01.003
  4. Gu, J., E. A. Smith, and J. D. Merritt, 1999: Testing energy balance closure with GOES-retrieved net radiation and in situ measured eddy correlation fluxes in BOREAS. Journal of Geophysical Research 104(D22), 27881-27893 https://doi.org/10.1029/1999JD900390
  5. Hong, J. K., and J. Kim, 2002: On processing raw data from micrometeorological field experiments. Korean Journal of Agricultural and Forest Meteorology 4(2), 119-126
  6. Howell, J. F., and J. Sun, 1999: Surface-layer fluxes in stable conditions. Boundary-Layer Meteorology 90, 495- 520 https://doi.org/10.1023/A:1001788515355
  7. Kaimal, J. J., J. C. Wyngaard, Y. Izumi, and O. R. Cote, 1972: Spectral characteristics of surface layer turbulence. Quarterly Journal of Royal Meteorologyl Society 98, 563-589 https://doi.org/10.1002/qj.49709841707
  8. Kaimal, J. J., and J. J. Finnigan, 1994: Atmospheric Boundary Layer Flows. Oxford University Press, New York, 289pp
  9. Katul, G., C. Hsieh, D. Bowling, K. Clark, N. Shurpali, A. Turnipseed, J. Albertson, K. Tu, D. Hollinger, B. Evans, B. Offerle, D. Anderson, D. Ellsworth, C. Vogel, and R. Oren, 1999: Spatial variability of turbulent fluxes in the roughness sublayer of an even-aged pine forest. Boundary-Layer Meteorology 93, 1-28 https://doi.org/10.1023/A:1002079602069
  10. Kim, J., W. Kin, B. Lee, C. Cho, B. Choi, D. Lee, E. Park, J. Lee, J. Lim, J. Oh, J. Yun, and C. Rho, 2002: KOFLUX: A new network of reference sites for AsiaFlux/ FLUXNET and CAMP/CEOP. Proceedings of the Second International Workshop on Advanced Flux Network and Flux Evaluation, Jeju Island, Korea, 9-11 January, 6-7
  11. Lee, X., and X. Hu, 2002: Forest-air fluxes of carbon, water and energy over non-flat terrain. Boundary-Layer Meteorology 103, 277-301 https://doi.org/10.1023/A:1014508928693
  12. Lim, J. H., J. H. Shin, G. X. Jin, J. H. Chun, and J. S. Oh, 2003: Forest structure, site characteristics and carbon budget of the Kwangneung Natural Forest in Korea. Korean Journal of Agricultural and Forest Meteorology 5(2), 101-109
  13. Mahrt, L., 1998: Flux sampling errors for aircraft and towers. Journal of the Atmospheric Sciences 15, 416-429
  14. Molder, M., A. Grelle, A. Lindroth and S. Halldin, 1999: Flux-profile relationships over a boreal forest-roughness sublayer corrections. Agricultural and Forest Meteorology 98-99, 645-658 https://doi.org/10.1016/S0168-1923(99)00131-8
  15. Moncrieff, J., R. Clement, J. Finnigan, and T. Meyers, 2004: Averaging, detrending, and filtering of eddy covariance time series. Handbook of Micrometeorology: A Guide for Surface Flux Measurement and Analysis, X. Lee, W. Massman, and B. Law (Eds.), Kluwer Academic Publishers, 7-31
  16. Nakamura, R., and L. Mahrt, 1999: Similarity theory for local and spatially averaged momentum fluxes. Agricultural and Forest Meteorology 108, 265-279 https://doi.org/10.1016/S0168-1923(01)00250-7
  17. Sun, J., J. F. Howell, S. K. Esbensen, L. Mahrt, C. M. Greb, R. Grossman, and M. A. LeMone, 1996: Scale dependence of air-sea fluxes over the Western Equatorial Pacific. Journal of the Atmospheric Sciences 53, 2997-3012 https://doi.org/10.1175/1520-0469(1996)053<2997:SDOASF>2.0.CO;2
  18. Turnipseed, A. A., P. D. Blanken, D. E. Anderson, and R. K. Monson, 2002: Energy budget above a high-elevation subalpine forest in complex topography. Agricultural and Forest Meteorology 110, 177-201 https://doi.org/10.1016/S0168-1923(01)00290-8
  19. Vickers, D., and L. Mahrt, 1997: Quality control and flux sampling problems for tower and aircraft data. Journal of Atmospheric and Oceanic Technologies 14, 512-526 https://doi.org/10.1175/1520-0426(1997)014<0512:QCAFSP>2.0.CO;2
  20. Vickers, D., and L. Mahrt, 2006: A solution for flux contamination by mesoscale motion with very weak turbulence. Boundary-Layer Meteorology 118, 431-447 https://doi.org/10.1007/s10546-005-9003-y
  21. Webb, E. K., G. I. Pearman, and R. Leuning, 1980: Correction of flux measurements for density effects due to heat and water vapor transfer. Quarterly Journal of Royal Meteorology Society 106, 85-100 https://doi.org/10.1002/qj.49710644707
  22. Wilczak, J. M., S. P. Oncley, and S. A. Sage, 2001: Sonic anemometer tilt correction algorithms. Boundary-Layer Meteorology 99, 127-150 https://doi.org/10.1023/A:1018966204465
  23. Wilson, K. B., A. H. Goldstein, E. Falge, M. Aubinet, D. D. Baldocchi, P. Berbigier, C. Bernhofer, R. Ceulemans, H. Dolman, C. Field, A. Grelle, A. Ibrom, B. E. Law, A. Kowalski, T. Meyers, J. Moncrieff, R. Monson, W. Oechel, J. Tenhunen, R. Valentini, and S. Verma, 2002: Energy balance closure at FLUXNET sites. Agricultural and Forest Meteorology 113, 223-243 https://doi.org/10.1016/S0168-1923(02)00109-0
  24. Wyngaard, J. C., O. R. Cot, and Y. Izumi, 1971: Local free convection, similarity and the budgets of shear stress and heat flux. Journal of the Atmospheric Sciences 28, 1171-1182 https://doi.org/10.1175/1520-0469(1971)028<1171:LFCSAT>2.0.CO;2

Cited by

  1. Effects of Different Averaging Operators on the Urban Turbulent Fluxes vol.24, pp.2, 2014, https://doi.org/10.14191/Atmos.2014.24.2.197
  2. Characteristics of canopy turbulence over a deciduous forest on complex terrain vol.47, pp.3, 2011, https://doi.org/10.1007/s13143-011-0016-9
  3. Quality Control and Characteristic of Eddy Covariance Data in the Region of Nakdong River vol.23, pp.3, 2013, https://doi.org/10.14191/Atmos.2013.23.3.307