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Title: Inter‐annual hydroclimatic variability in coastal Tanzania

Climatic controls regulate the coupled natural and human systems in coastal Tanzania, where mangrove wetlands provide a wealth of ecosystem services to coastal communities. Previous research has explained the precipitation seasonality of eastern Africa in terms of the local monsoons. This research examines a wider range of hydroclimatic variables, including water vapour flux, evapotranspiration, runoff, and ocean salinity, and the sources of low‐frequency atmosphere–ocean variability that support mangrove productivity and associated ecosystem services. Results confirm previous work suggesting that the northeast monsoon (kaskazi) largely corresponds to the “short rains” of October–December and extends through February, while the southeast monsoon (kusi) corresponds to the “long rains” of March–May and the drier June–September. The Indian Ocean Dipole (IOD) and, to a lesser extent, El Niño–Southern Oscillation (ENSO) are important modulators not only of precipitation (as has been shown previously) but also of water vapour flux, evapotranspiration, runoff, and salinity variability. Duringkaskazi, positive (negative) hydroclimatic anomalies occur during positive (negative) IOD, with a stronger IOD influence occurring during its positive phase, when seasonal anomalies of precipitation, evapotranspiration, and runoff exceed +50, 25, and 100%, and nearby salinity decreases by 0.5 practical salinity units. Duringkusi, the contrast between the positive and negative IOD modes is subtler, and the pattern is dictated more by variability in “long rains” months than in the dry months. The coincidence of the positive IOD and El Niño amplify this hydroclimatic signal. Because previous work suggests the likelihood of increased tendency for positive IOD and increased moisture variability associated with El Niño events in the future, wetter conditions may accompany thekaskazi, with less change expected during thekusi. These results advance understanding of the key environmental drivers controlling mangrove productivity and wetland spatial distribution that provide ecosystem services essential to the well‐being of the human population.

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Author(s) / Creator(s):
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Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
International Journal of Climatology
Page Range / eLocation ID:
p. 4736-4750
Medium: X
Sponsoring Org:
National Science Foundation
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