In‐cloud variability of LIDAR depolarization of polar and midlatitude cirrus

LIDAR depolarization is commonly used for discriminating liquid and ice particles. Since depolarization depends in a complicated manner on particle shape and size, in‐cloud variability of depolarization has been used as an indicator of the microphysical homogeneity of cirrus. The comparison between midlatitude (Florence, Italy, 43. 60°N) and polar (Dumont d'Urville, Antarctica, 66. 68°S) cirrus showed a lower mean depolarization and a higher in‐cloud uniformity of cloud depolarization for polar clouds in the (−80, −50°C) temperature range. A wider in‐cloud variability of depolarization was observed in polar clouds at higher temperatures (−50, −30°C), reflecting the presence of supercooled liquid layers. The large in‐cloud variability of depolarization in Florence cirrus could be explained with a microphysics that is dynamically and chemically perturbed as compared with the polar site. Aged jet contrails are, in fact, present in many Florence cirrus records

ON THE ASSIMILATION OF GNSS PWV MEASUREMENTS IN HEAVY TO TORRENTIAL RAIN EVENTS IN DAVAO CITY, PHILIPPINES

A standalone Global Navigation Satellite System (GNSS) receiver was utilized in this study to get a measure of the atmospheric water vapor in Davao City, Philippines. It aims to monitor the variability of GNSS precipitable water vapor (PWV) especially during heavy to torrential rain. The results of the study showed a positive correlation between GNSS-PWV and precipitation especially in these severe (heavy to torrential) rain events which implies that the assimilation of atmospheric water vapor measurements can improve forecasts of such events

Activity Pattern of School/University Tenants and their Family Members in Metro Manila – Philippines

Existing studies that focus on personal exposure to or the deposition dose of particulate pollution in developing regions are limited. Hence, in this study, as a first step, we present results on how people spend their daily time in Metro Manila, Philippines. This information is critical to assessing personal exposure to and the deposition dose of particulate pollutants. We found that people spend less time at home on workdays than weekends (52% versus 70%), the fraction of time spent at work/school increases with age until retirement, adult males spend less time at home than females (18% versus 28%), and people spend most of their time indoors (84%). The biggest difference from previous studies is the discovery that people in Metro Manila spend 11% of their daily time on average in transit traffic, which is up to 2.2 times more than in Europe, America, Korea, or China. Longer times in transit traffic subject the population of Metro Manila to a higher risk of increased exposure to toxic pollutants and adverse health symptoms. The main results of this research will be used in an upcoming study on the personal deposition dose of soot

Aerosol Particle and Black Carbon Emission Factors of Vehicular Fleet in Manila, Philippines

Poor air quality has been identified as one of the main risks to human health, especially in developing regions, where the information on physical chemical properties of air pollutants is lacking. To bridge this gap, we conducted an intensive measurement campaign in Manila, Philippines to determine the emission factors (EFs) of particle number (PN) and equivalent black carbon (BC). The focus was on public utility jeepneys (PUJ), equipped with old technology diesel engines, widely used for public transportation. The EFs were determined by aerosol physical measurements, fleet information, and modeled dilution using the Operational Street Pollution Model (OSPM). The results show that average vehicle EFs of PN and BC in Manila is up to two orders of magnitude higher than European emission standards. Furthermore, a PUJ emits up to seven times more than a light-duty vehicles (LDVs) and contribute to more than 60% of BC emission in Manila. Unfortunately, traffic restrictions for heavy-duty vehicles do not apply to PUJs. The results presented in this work provide a framework to help support targeted traffic interventions to improve urban air quality not only in Manila, but also in other countries with a similar fleet composed of old-technology vehicles

Respiratory tract deposition of inhaled roadside ultrafine refractory particles in a polluted megacity of South-East Asia

Recent studies demonstrate that Black Carbon (BC) pollution in economically developing megacities remain higher than the values, which the World Health Organization considers to be safe. Despite the scientific evidence of the degrees of BC exposure, there is still a lack of understanding on how the severe levels of BC pollution affect human health in these regions. We consider information on the respiratory tract deposition dose (DD) of BC to be essential in understanding the link between personal exposure to air pollutants and corresponding health effects. In this work, we combine data on fine and ultrafine refractory particle number concentrations (BC proxy), and activity patterns to derive the respiratory tract deposited amounts of BC particles for the population of the highly polluted metropolitan area of Manila, Philippines. We calculated the total DD of refractory particles based on three metrics: refractory particle number, surface area, and mass concentrations. The calculated DD of total refractory particle number in Metro Manila was found to be 1.6 to 17 times higher than average values reported from Europe and the U.S. In the case of Manila, ultrafine particles smaller than 100 nm accounted for more than 90% of the total deposited refractory particle dose in terms of particle number. This work is a first attempt to quantitatively evaluate the DD of refractory particles and raise awareness in assessing pollution-related health effects in developing megacities. We demonstrate that the majority of the population may be highly affected by BC pollution, which is known to have negative health outcomes if no actions are taken to mitigate its emission. For the governments of such metropolitan areas, we suggest to revise currently existing environmental legislation, raise public awareness, and to establish supplementary monitoring of black carbon in parallel to already existing PM 10 and PM 2.5 measures. © 201

1999 Philippine Talent Search for Young Scientists (PTSYS) award

Dr. Edgar Vallar of the Chemistry Department, placed second in the 1999 Philippine Talent Search for Young Scientists (PTSYS) Award among 16 qualified candidates from all over the country. Vallar presented his research titled Generation of 589 nm Laser Radiation by Sum-Frequency of the 1319 nm Output of a Single Nd:YAG Laser (II) to a NAST panel in March, 1999

1999 Philippine talent search for young scientists

Dr. Edgar Vallar of the Physics Department and Dr. Elaine Tolentino of the Chemistry Department received their awards for winning the second and third prizes, respectively, in the 1999 Philippine Talent Search for Young Scientists sponsored by the National Academy of Science and Technology (NAST)

Altitude profile of the effective radius of atmospheric boundary layer aerosols retrieved from simultaneous two-wavelength lidar measurement

The altitude profile of the effective radius, reff, of atmospheric boundary layer aerosols was retrieved from simultaneous two-wavelength lidar measurement near Manila Bay. The effective radius was retrieved using a simple method that makes use of the angstrom coefficient, δ, obtained from the extinction coefficients at the two wavelengths. The altitude profiles of the extinction coefficients at 532-nm and 1064-nm lidar wavelengths were obtained using Fernald\u27s inversion algorithm combined with Klett\u27s boundary value algorithm, used to obtain the aerosol extinction coefficient at the reference height. Assuming a lognormal size distribution, with a geometric standard deviation of 1.54, for atmospheric boundary layer aerosols, and a constant refractive index of 1.45 - 0i, the angstrom coefficient is determined at different mode radius, rg, using Mie Scattering Theory. A curve fitting analysis using the method-of-least-squares is done on the theoretical value of δ to obtain a sixth-order polynomial equation flint gives the dependence of δ with rg. The altitude profile of reff is retrieved by using the measured value of δ into the equation. This method was applied to actual lidar experiments and the effective radius of the atmospheric boundary layer aerosols was observed to vary between 0.26 μm to 0.29 μm within the layer

Simultaneous two-wavelength lidar measurement of cloud and boundary layer aerosol extinction coefficients

Simultaneous two wavelength LIDAR measurements of clouds and boundary layer aerosols were performed near Manila Bay, Philippines. The two-wavelength LIDAR system employs the simultaneous outputs at 1064-nm (420 mJ), and 532-nm (175 mJ) of a Q-Switched, 20-Hz Nd:YAG laser, and a 203.20-mm diameter Schmidt Cassegrain telescope set for 1-mrad field-of-view. The vertically-pointing, biaxial Mie LIDAR facility became operational early last year and is in the STRC building (14.339°N, 120.595°E) of De La Salle University (DLSU), Taft Avenue, Manila. LIDAR measurements were obtained in 1-minute intervals from 0812-0830 hours (local time) on December 20, 1999 and 0650-0930 hours (local time) on March 23, 2000. Extinction coefficients for these boundary layer aerosols and clouds were computed using Klett\u27s modified inversion algorithm. The extinction coefficients for the clouds observed on December 20 were 20 - 100 km-1 (1064 nm) and 5 - 40 km-1 (532 nm). Boundary layer aerosols found on the same day had extinctions of 10 km-1 for both wavelengths and reached up to 300 m above the site. The March 23 data show mostly boundary, layer aerosols from 200 - 600 m above the LIDAR having extinction values of 6 - 8 km-1 for both wavelengths

Atmospheric turbidity measurements using a 355NM-532NM lidar and a sunphotometer in Manila, Philippines

Real-time measurements of atmospheric turbidity were conducted in Manila, Philippines using the De La Salle University (DLSU) 355nm-532nm Mie LIDAR and Middleton SP02 4-channel sunphotometer. The DLSU Mie LIDAR system and the Middleton SP02 Sunphotometer are currently housed in the Science & Technology Research Center of DLSU, Manila, Philippines. DLSU is located in the center of Manila and is approximately 900 meters from Manila Bay. The DLSU LIDAR mainly consists of a 20-Hz, Q-Switched Nd:YAG laser and 20-cm diameter, 800-mm focal length Newtonian telescope. The SP02 Sunphotometer is a 1.25-kg commercial 4-channel Sunphotometer with center wavelengths at 368nm, 500nm, 675nm and 862nm (10-nm bandwidth). The sunphotometer was attached to a homemade tracker mount that tracks the sun and gets data automatically throughout the day. DLSU LIDAR researchers built LabView-based VI\u27s for both the LIDAR and the sunphotometer enabling automatic data acquisition and processing. A detailed description of both systems can be found in www.dlsu-lidar.tk. The optical depth was determined from the data of each instrument. The Ångström turbidity law was then utilized to obtain the atmospheric turbidity. Typical values of turbidity vary from 0.0 to 0.5. For clean, clear, turbid and very turbid atmospheres, the turbidity values are 0.0, 0.1, 0.2 and 0.4, respectively. Experiments were conducted last 2010 January 08, 12 and 22. The average turbidity up to 400 meters horizontal range from the LIDAR site was determined. The LIDAR derived turbidity values were 0.184, 0.23, and 0.0295, respectively for the three dates. The corresponding sunphotometer values are 0.191, 0.235, and 0.0280, respectively. The January 08 and 12 values show a turbid atmosphere while the January 22 value indicates a relatively clear atmospheric condition