6 research outputs found
Observations of DG Tauri with the Keck Interferometer
We present the first science results from the Keck Interferometer, a
direct-detection infrared interferometer utilizing the two 10-meter Keck
telescopes. The instrument and system components are briefly described. We then
present observations of the T Tauri object DG Tau, which is resolved by the
interferometer. The resolved component has a radius of 0.12 to 0.24 AU,
depending on the assumed stellar and extended component fluxes and the model
geometry used. Possible origins and implications of the resolved emission are
discussed.Comment: 10 pages, 2 figures, to appear in ApJ Letter
The weight of the flood‐of‐record in flood frequency analysis
The standard approach to flood frequency analysis (FFA) fits mathematical functions
to sequences of historic flood data and extrapolates the tails of the distribution
to estimate the magnitude and likelihood of extreme floods. Here, we identify the
most exceptional floods in the United States as compared against other major
floods at the same location, and evaluate how the flood-of-record (Qmax) influences
FFA estimates. On average, floods-of-record are 20% larger by discharge than their
second-place counterparts (Q2), and 212 gages (7.3%) have Qmax:Q2 ratios greater
than two. There is no clear correspondence between the Qmax:Q2 ratio and median
instantaneous discharge, and exceptional floods do not become less likely with
time. Excluding Qmax from the FFA causes the median 100-year flood to decline
by −10.5%, the 200-year flood by −11.8%, and the 500-year flood by −13.4%.
Even when floods are modelled using a heavy tail distribution, the removal of Qmax
yields significantly “lighter” tails and underestimates the risk of large floods.
Despite the temporal extension of systematic hydrological observations in the
United States, FFA is still sensitive to the presence of extreme events within the
sample used to calculate the frequency curve