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<p>This study presents continuous, real-time monitoring of the atmospheric boundary layer (ABL) dynamics over Dibrugarh, an easternmost location of the state of Assam in Northeast India, using a Ceilometer Lidar CL31. A distinct diurnal cycle and strong seasonal variability in ABL height (ABLH) are observed. The ABL reaches its maximum height (~ 1750&#xa0;m and ~ 1450&#xa0;m) during the pre-monsoon (March–May) and monsoon (June–September) seasons, while it remains shallower (~ 925&#xa0;m and ~ 1025&#xa0;m) during the post-monsoon (October–November) and winter (December–February) periods. Surface sensible heat flux and latent heat flux significantly influence ABL growth during the warmer months. The diurnal evolution of the lifting condensation level (LCL) is also analysed to investigate the ABL interaction with cloud formation and development. It is observed that the LCL generally lies above the ABL. However, the ABL often exceeds the LCL during afternoon hours in the pre-monsoon and monsoon seasons, suggesting favourable conditions for cumulus cloud formation. Ceilometer-derived ABLH are further compared with European Centre for Medium-Range Weather Forecasts version 5 (ERA5) reanalysis data. The ERA5 is observed to capture the diurnal and seasonal evolution of ABL but is underestimating the Ceilometer retrieved ABL with a mean bias error (MBE) (root mean square error, RMSE) values ranging ~ − 5.5&#xa0;m – − 183.6&#xa0;m (~ 97.2&#xa0;m – 316.7&#xa0;m). Seasonally, the highest correlation coefficient of ~ 0.98 is observed in the monsoon with MBE (RMSE) − 53&#xa0;m (87.6&#xa0;m). However, the highest MBE and RMSE, despite a good correlation (0.97), in pre monsoon suggests a discrepancy in reanalysis data, mainly arising from the differences in retrieval methods, where Ceilometer uses gradient method while ERA5 uses the Bulk Richardson method. The present observation of real-time diurnal ABL cycle will be helpful in explaining the diurnal evolution of atmospheric composition specially the aerosols and trace gases measured over the study location using ground-based observations as well as those simulated using climate models.</p>

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Monitoring the Atmospheric Boundary Layer Height Using Ceilometer Lidar Over the Northeast India

  • 期刊论文

  • 发表日期：

    2026年1月2日

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  • Partha Jyoti Sahu,
  • Binita Pathak,
  • Som Kumar Sharma,
  • Barsha Dutta,
  • Uday Bhattacharjee,
  • Aniket Chakraborty,
  • Aniket Patel,
  • Dharmendra Kamat,
  • Pradip Kumar Bhuyan,
  • Arup Borgohain,
  • Kalyan Bhuyan

摘要

This study presents continuous, real-time monitoring of the atmospheric boundary layer (ABL) dynamics over Dibrugarh, an easternmost location of the state of Assam in Northeast India, using a Ceilometer Lidar CL31. A distinct diurnal cycle and strong seasonal variability in ABL height (ABLH) are observed. The ABL reaches its maximum height (~ 1750 m and ~ 1450 m) during the pre-monsoon (March–May) and monsoon (June–September) seasons, while it remains shallower (~ 925 m and ~ 1025 m) during the post-monsoon (October–November) and winter (December–February) periods. Surface sensible heat flux and latent heat flux significantly influence ABL growth during the warmer months. The diurnal evolution of the lifting condensation level (LCL) is also analysed to investigate the ABL interaction with cloud formation and development. It is observed that the LCL generally lies above the ABL. However, the ABL often exceeds the LCL during afternoon hours in the pre-monsoon and monsoon seasons, suggesting favourable conditions for cumulus cloud formation. Ceilometer-derived ABLH are further compared with European Centre for Medium-Range Weather Forecasts version 5 (ERA5) reanalysis data. The ERA5 is observed to capture the diurnal and seasonal evolution of ABL but is underestimating the Ceilometer retrieved ABL with a mean bias error (MBE) (root mean square error, RMSE) values ranging ~ − 5.5 m – − 183.6 m (~ 97.2 m – 316.7 m). Seasonally, the highest correlation coefficient of ~ 0.98 is observed in the monsoon with MBE (RMSE) − 53 m (87.6 m). However, the highest MBE and RMSE, despite a good correlation (0.97), in pre monsoon suggests a discrepancy in reanalysis data, mainly arising from the differences in retrieval methods, where Ceilometer uses gradient method while ERA5 uses the Bulk Richardson method. The present observation of real-time diurnal ABL cycle will be helpful in explaining the diurnal evolution of atmospheric composition specially the aerosols and trace gases measured over the study location using ground-based observations as well as those simulated using climate models.