Characterization of columnar water vapor measurements and its comparison with model estimates and surface meteorological parameters Over Manila, Philippines (14.567° N, 120.980° E)


College of Science



Document Type

Conference Proceeding

Source Title

35th Asian Conference on Remote Sensing 2014, ACRS 2014: Sensing for Reintegration of Societies

Publication Date



The temporal variation of precipitable water (PWmeas) in the near-infrared (936 nm) band at Manila, Philippines (14.567° N, 120.980° E) was investigated using a Microtops II Sun photometer and Ozone Meter (spectral radiometer) in 30-min interval observations (0900H - 1200H, 1300H - 1600H LT) from February to May 2014. Precipitable water (PWcalc) was also computed from surface meteorological measurements (i.e., relative humidity and surface temperature) and the Butler model. Results show a large day-to-day variability of the PWmeas values due to varied meteorological and sky conditions. PWmeas yielded a positively skewed distribution; 46.0 % of all the PW observations fall from 1.80 cm to 2.60 cm. The daytime median PWmeas was 2.79 cm at quartile deviation (QD)=0.608, with maximum PWmeas=4.35 cm and minimum PWmeas=1.88 cm. Kruskal-Wallis Analysis of Variance was performed to compare the PWmeas values for the (a) monthly observations, (b) daily measurements, and (c) morning (A.M.) & afternoon (P.M.) monitoring. A p-value of <0.05 was obtained for (a), showing a significant difference among PWmeas values for the months of February, March, April, and May. On the other hand, a p-value of 0.222 was obtained for (b), illustrating that there was no significant difference among PWmeas values at any of the 30-min interval observations. Moreover, a p-value of <0.05 was obtained for (c), indicating a significant difference between A.M. & P.M. PWmeas values. Further, the obtained PW was correlated using the Spearman Rank Order Correlation with relative humidity (rS=0.0860), surface temperature (rS=0.572), and dew-point temperature (rS=0.822). Lastly, PWcalc was compared with PWmeas (rS=0.823) revealing a strong correlation.


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