Dr. Mark Lander

Dr. Mark Lander
Professor of Water Resources Engineering


Phone: 671-735-2690 (fax 734-8890) (GMT+10 hrs)
mlander(weri)uguam.uog.edu?subject=Faculty - WeriGuam.org

Recent Projects

Rainfall Climatology for Saipan: Distribution, Return Periods, El Niño, Tropical Cyclones, and Long-term variations.

Completed in 2004, the principal findings of this project were:

  1. The distribution of mean annual rainfall on Saipan is affected by the topography, and the mean annual rainfall totals among recording stations on Saipan differ by as much as 15 inches (380 mm).
  2. The region in the vicinity of Saipan's International Airport receives the lowest annual total of about 75 inches (1900 mm). The highest mean annual rainfall of approximately 90 inches (2300 mm) occurs at Capitol Hill, and extends along the high ground from Marpi to Mount Tagpochau.
  3. Intensity-duration-frequency (IDF) tables were generated using the short Saipan rainfall data sets, and with consideration of rainfall properties of typhoons. The intensity values at most durations and frequencies are higher than others have reported.
  4. It is likely that typhoons are the cause of the highest rainfall intensities at all durations (from 15 minutes to 24 hours). Typhoon rainfall is negligibly affected by the topography of the island. Therefore, the return periods of extreme rain rates should be considered uniform across the whole island.
  5. More rainfall on Saipan occurs in the 12-hour span between midnight and sunrise than in the 12-hour span between noon and midnight; with an absolute minimum in the evening. This is the typical rainfall distribution over the open ocean undisturbed by the effects of island heating, and is caused by diurnally varying radiative processes in the tropical oceanic atmosphere.
  6. Month-to-month fluctuations of rainfall on Saipan are influenced by the Madden-Julian Oscillation (MJO).
  7. Inter-annual variations of Saipan's rainfall are closely linked to the El Niño/Southern Oscillation (ENSO) phenomenon. To some extent, the occurrence of typhoons in Saipan is also linked to ENSO.
  8. Large inter-decadal variations in rainfall (and also in the distribution of typhoons) are noted. The causes of these remain unknown. Inter-decadal variations of rainfall and other hydro-meteorological phenomena render the search for signals of long-term climate change very difficult. (Funding source: U.S. Geological Survey)

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