A107-05
Cirrus Cloud Statistics and Potential Effects on Surface Heating and Aerosol Loading in Metro Manila using Ground-Based High Spectral Resolution Lidar
Thursday, 10 December 2020: 20:46
Virtual
Shane Marie Aurelio Visaga1,2, Gemma Teresa T Narisma3, Lyndon Mark Payanay Olaguera1, Maria Obiminda L Cambaliza1,2, Faye Abigail T Cruz4, James Bernard B. Simpas5, Robert Holz6, Sebastian Schmidt7, Ralph Kuehn8, Edwin W Eloranta9 and Jeffrey S. Reid10, (1)Ateneo de Manila University, Quezon City, Philippines, (2)Manila Observatory, Quezon City, Philippines, (3)Atmospheric Science Program, Department of Physics, School of Science and Engineering, Ateneo de Manila University, Quezon City, Philippines, (4)Regional Climate Systems Laboratory, Manila Observatory, Quezon City, Philippines, (5)Ateneo de Manila University, Department of Physics, Quezon City, Philippines, (6)UW SSEC, Madison, WI, United States, (7)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (8)University of Wisconsin Madison, Madison, WI, United States, (9)University of Wisconsin Madison, Space Science and Engineering Center, Madison, WI, United States, (10)Marine Meteorology Division, Monterey, CA, United States
Abstract:
This study examines tropical cirrus cloud effects on boundary layer processes, particularly the potential influence of cirrus optical depth on surface heating and consequent aerosol loading within the planetary boundary layer (PBL), over an urban mixed background site in Metro Manila, Philippines. Cloud, aerosol and radiation measurements from instruments such as ground-based high-spectral resolution lidar (HSRL) and a Filtered Sunshine Pyranometer (F-SPN1) at the Manila Observatory supersite are obtained from the 2019 period of the CAMP2Ex Weather and CompoSition Monitoring (CHECSM) observation campaign. Cirrus clouds from 10-15 km are detected from daytime (06:00-15:00 Philippine Time (PHT)) HSRL data when not attenuated by low clouds such as during no rain days. Thus, the analysis focuses on cases when cirrus clouds are the main drivers for the shortwave surface flux quantified by pyranometers collocated with the HSRL.
Results show that the Northeast Monsoon (NEM) season from December to March contributes 47% to no rain days in 2019. NEM is also characterized by more frequent and optically thinner cirrus compared to other months. Meanwhile, the Southwest Monsoon (SWM) season from June to September only contributes 21% to the no rain days, but cirrus occurrence is 5-7% higher than other seasons. Diurnal analysis shows that cirrus clouds are 3-5% more prevalent during the morning PBL growth period from 08:00-11:00 PHT compared to other times of the day. Days with overcast cirrus conditions for at least 3 hours will be selected for further analysis on cirrus impacts on solar radiation, PBL height and its growth rate. Cirrus effects on aerosol loading within the PBL will also be investigated. Findings of the study can contribute to better understanding of cloud and boundary layer processes that can also improve numerical simulations of the boundary layer in urban areas in the Philippines.
