Atmospheric-Boundary-Layer Height Retrieval using Microwave Radiometer and Lidar Sensors: Algorithms and Error Estimation

The research work involves developing algorithms to retrieve the atmospheric boundary layer height from synergetic observations by lidar and microwave radiometer. Atmospheric Boundary-Layer Height (ABLH) is an important parameter for several applications ranging from weather, air-quality and dispersion models, meteorology and avionics. There are several instruments and methods to retrieve the ABLH. However, none of these instruments or methods can measure the development of the ABLH under all atmospheric conditions. For example, aerosol signatures measured by backscatter lidars can be used to determine the ABLH but this approach is reasonable only when the atmosphere is well-mixed. Microwave Radiometer (MWR) derived profiles have low vertical-resolution and cannot resolve fine structures in the boundary-layer, especially, at higher altitudes. We aim to develop a combined algorithm which can provide ABLH estimates through the full diurnal cycle including daytime Mixing Layer (ML), Stable Boundary-Layer (SBL) and transition times.

The daytime Mixing Layer Height (MLH) and the nighttime Stable Boundary-Layer Height (SBLH) are determined by combining their coarse estimates from the MWR measurements with the aerosol backscatter from the lidar. The combination is achieved in the framework of an Extended Kalman Filter (EKF) where the fitting ranges of the EKF are defined by the coarse MWR estimates. The MWR, therefore, plays the role of layer attribution which is especially more pronounced in the multiple aerosol layers and cloudy conditions. For the transition regions only MWR-based estimates are used.

The proposed approach, by exploiting the synergy between the two instruments, enables to detect ABLH with original vertical and temporal resolutions. Test cases combining simulated data as well measured data for a co-located lidar-ceilometer and a MWR are presented.

The simulated data is obtained from the Dutch Atmospheric Large Eddy Simulation (DALES) model for boundary-layer studies. LES provides a virtual laboratory that can be used to investigate the difference in ABLH between aerosol and temperature based estimates without the shortcomings of the instruments, e.g., instrument noise, calibration error and systematic bias.

Doppler wind lidar along with radiosondes (whenever available) are used to assess the quality of the synergetic ABLH estimates. Measurement data from the HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany is used to test the proposed method.

Peer-reviewed journal articles

[4] Saeed, U., Rocadenbosch, F., “Variance processing for stable boundary-layer height estimation using backscatter lidar data: A discussion,” IEEE Transactions on Geoscience and Remote Sensing. (under prep.).

[3] Saeed, U., Rocadenbosch, F., “On the need of a synergetic mixing-layer height retrieval method using backscatter lidar returns and microwave-radiometer temperature observations,” IEEE Transactions on Geoscience and Remote Sensing. (Submitted, Feb. 2016).

[2] Saeed, U., Rocadenbosch, F., Crewell, S., “Adaptive Estimation of the Stable-Boundary-Layer Height Using Combined Lidar and Microwave Radiometer Observations,” IEEE Transactions on Geoscience and Remote Sensing. (Accepted with minor review).

[1] Lange, D., Tiana-Alsina, J., Saeed, U., Tomás, S., Rocadenbosch, F., “Atmospheric Boundary-Layer height monitoring using a Kalman filter and backscatter lidar,” IEEE Transactions on Geoscience and Remote Sensing, 52(8), 4717–4728 (2014).

Conferences

[9] Saeed, U., Löhnert, U., Heus, T., Neggers, R., Rocadenbosch, F., and Crewell, S. “On the need of a direct retrieval method for mixing-layer height using simulated brightness temperature measurements,” 18^th International Symposium for the Advancement of Boundary-Layer Remote Sensing (ISARS), Varna, Bulgaria (2016). (Accepted).

[8] Saeed, U., Barragán, R., and Rocadenbosch, F., “Enhanced signal-to-noise ratio estimation for tropospheric lidar channels,” EGU General Assembly 2016, Vienna, Austria (2016).

[7] Saeed, U., Löhnert, U., Heus, T., Neggers, R., Rocadenbosch, F., and Crewell, S. “Can we retrieve mixing-layer height directly from the brightness temperature measurements?” MicroRad, Helsinki, Finland (2016).

[6] Saeed, U., and Rocadenbosch, F., “Uncertainty on atmospheric boundary-layer height estimation due to measurement errors in the ground-based lidar and microwave radiometer data,” IEEE Young Professionals Conference, Barcelona, Spain (2015).

[5] Saeed, U., Rocadenbosch, F., and Crewell, S., “Performance test of the synergetic use of simulated lidar and microwave radiometer observations for mixing-layer height detection,” Proc. of SPIE, Toulouse, France (2015).

[4] Saeed, U., and Rocadenbosch, F., “Exploiting microwave radiometer-derived temperature profile structure for stable boundary-layer height estimation,” Proc. of SPIE, Toulouse, France (2015).

[3] Saeed, U., Rocadenbosch, F., and Crewell, S., “Synergetic use of lidar and microwave radiometer observations for boundary-layer height detection,” Proc. of IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, Italy (2015).

[2] Saeed, U., Rocadenbosch, F., and Crewell, S., “Adaptive estimation of the stable boundary-layer height using backscatter lidar data and a Kalman filter,” Proc. of IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Milan, Italy (2015).

[1] Saeed, U., Tiana-Alsina, J., Rocadenbosch, F., and Crewell, S., “Atmospheric boundary layer height estimation using combined microwave radiometer and lidar data,” The World Weather Open Science Conference (WWOSC), Montreal, Canada, 16 - 21 August (2014).