CO-VARIATION OF ANNUAL PRECIPITATION AND RIDGE-VALLEY RELIEF

Spatial variability in annual average precipitation rates from TRMM (Tropical Rainfall Measuring Mission) satellite precipitation radar data corresponds with spatial variability in ridge-valley relief in several tropical mountain ranges including the Cordillera de Talamanca of Costa Rica, the Sierra Madre Occidental of Mexico, the Peruvian Andes, and the Western Ghats of India. We examine topography derived from SRTM (Shuttle Radar Topography Mission) data and precipitation patterns in swaths cutting perpendicular to the strike of these mountain ranges. Ridge-valley relief is defined as the standard deviation of topographic elevation parallel to the strike of the range. Ridge-valley relief varies systematically across these ranges in concert with annual average precipitation. Where precipitation rates are high, ridge-valley relief is diminished and where precipitation rates are low, ridge-valley relief is maximized. These relationships are consistent with an idealized model of the co-evolution of orographic precipitation with topography. This model highlights the potential for mutual adjustment between precipitation patterns and topography to be realized through spatial variability in topographic relief. We suggest that spatial variability in ridge-valley relief may be a characteristic signature of the dynamic relationship between topography and precipitation-driven erosional processes.