Arecibo’s participation in PRADACS campaign

1. Arecibo’s participation in PRADACS campaign Shikha Raizada and Craig A. Tepley

2. Objectives • To investigate the properties of dust during long range transport from Sahara to Caribbean • Study of cloud properties during intense dust periods. • How does Long Range Transported African Dust (LRTAD) influences the cloud properties and precipitation levels in PR?

3. Methodology • Use Sun-photometers at Arecibo and rain-forest site. • At Arecibo: 3 handheld Radiometers • FOV ~ 2.5 deg • Two are identical and can give ozone, water vapor and AOT • One has 5 wavelengths: 380, 440,500,675 and 870 nm • Questions that need to be looked into by using Radiometers • What is the variation in AOT at CSJ, PE and Arecibo? • Is size distribution similar at Arecibo and CSJ? • Investigate which particle sizes dominate at CSJ, PE, and Arecibo. • This will reflect light on how LRTAD changes in marine(CSJ) and non-marine (Arecibo) environment and can be the first step in understanding how transport processes effect dust properties.

4. Methodology: Examples of Previous Measurements

5. Methodology: Examples of Previous Measurements What would be the daily variation of different particles during strong dust events at Arecibo, CSJ and PE?

6. Methodology: Other instruments • Compare data from weather stations located at Arecibo, PE, and CSJ sites • Weather station is located on the Platform and one in the lidar lab building http://www.naic.edu/~phil/hardware/weatherstation/weatherstation.html • SomeParameters that can be obtained: • Rain Intensity, Humidity, Rain Rate (Running 5-minute rain rate) • Extinction Coefficient, Visibility • Wind-speed • Saturated Vapor Pressure, Vapor Pressure, Dry air Pressure • One second Temperature Reading • Relative Humidity

7. Methodology: Other instruments • Use lidar • Layer heights: What are the layer heights during strong LRTAD events? • Lidar ratio or backscattering coefficient: Quantize the contribution of aerosols relative to pure molecular scattering. • AngstromCoefficient (x) : Wavelength Dependence of Aerosolscattering: Rayleigh: βm= nm / λ4 Aerosols: βa = na / λx • REAL CHALLENGE: • To obtain altitude information of particle sizes • To infer cloud shapes (needs polarization channels)

8. New Developments for Lower Atmospheric Studies Transmitter Nd:YAG Narrowband Pulsed Laser @ 1064nm,532nm, and 355 nm30Hz To Atmosphere Receiver PMT Green PMT Blue Interference Filter Narrowband Filters From Atmosphere APD (1064 nm) Telescope Optical Edge Filters (Long Pass)

9. New Developments for Lower Atmospheric Studies • An InliteIII-30 laser from Continuum has been ordered in Nov., 2010: • Thanks to NAIC, Cornell University for funding this. Characteristics of the transmitter: A Meade f/10,14 inch telescope has also been ordered, which will act as a part of receiver.

10. Aerosol Lidar Receiver and DAQ: Part of mobile aerosol lidar APD (1064 nm)DichroicsTransient Recorders PMTs (532/355 nm)ChopperFiberHV Scale: Receiver is ~18” long; PMTs are 1” dia. DAQ: Ethernet & LabView controlled

11. Current and Future endeavors • 3 Undergrads from Interamerican Univ. tested the Licel receivers and developed LABVIEW based data acquisition software. • We need to integrate and test a dedicated 3 color YAG, for a mobile lidar system. • Estimate the diurnal variation of AOT, particle sizes in the near future. • Excellent opportunity for UPR students to work with data and instruments.