The Sensitivity of Rainfall Distributions to Time, Space, and the Environment over Kwajalein Atoll
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North of the equator, winds converge causing bands of heavy rain in a region called the Intertropical Convergence Zone (ITCZ). Due to the small-scale processes that are not fully represented by weather models, modeled rainfall and its characteristics are often not indicative of what is observed in the ITCZ. This study attempts to bridge that gap by using observations from a weather radar on Kwajalein Atoll, located within the central-western tropical Pacific, as well as reanalysis data over Kwajalein Atoll to investigate characteristics of ITCZ rainfall. Two wet seasons are analyzed to quantify rainfall variations in terms of different spatial scales, temporal averaging, and environmental conditions. Rain observed by the radar is first categorized as either convective (i.e., heavy and sporadic) or stratiform (i.e., light and widespread). Rain rates, conditional rain rates, and rain area are calculated for different time (10 minutes to 1 day) and spatial (2 km to 128 km) scales and then compared to specific humidity (moisture in the atmosphere), omega (vertical motion in the atmosphere), and sea surface temperature (SST) to determine if a relationship exists between the large-scale environment and the observed rainfall characteristics. The results obtained from this study hold the potential to quantify to what extent environmental factors may influence precipitation intensity and extremes at Kwajalein Atoll. Significant results can lead to calibrating weather and climate models, which creates more accurate rainfall predictions through numerical weather prediction and analysis from radars.
Intertropical Convergence Zone
Sea Surface Temperature
Campbell, Lily Joy (2017). The Sensitivity of Rainfall Distributions to Time, Space, and the Environment over Kwajalein Atoll. Undergraduate Research Scholars Program. Available electronically from