Digital Data Sets of Depth-Duration Frequency of Precipitation for Oklahoma, USGS OFR 99-463.

These geospatial data sets consist of precipitation
stations used in a regional precipitation frequency analysis
for Oklahoma.

Data were used from precipitation gage stations with at least 10
years of record within Oklahoma and about 50 kilometers into
bordering states. Three different rain gage networks provided
the data (15-minute, 1-hour, and 1-day). Data were analyzed for
seven frequencies (expressed as recurrence intervals of 2-, 5-,
10-, 25-, 50-, 100-, and 500-years) and 12 durations (15-, 30-, and
60-minutes; 1-, 2-, 3-, 6-, 12-, and 24-hours; and 1-, 3-, and
7-days). Precipitation annual maxima (depths) were determined
from the station data for each duration for 110 15-minute
stations (used for 15-, 30-, and 60-minute durations), 141
hourly stations (used for 1-, 2-, 3-, 6-, 12-, and 24-hour
durations), and 413 daily stations (used for 1-, 3-, and 7-day
durations).

Statistical methods were used to estimate precipitation depths
for each duration-frequency at each station. These station
depth-duration-frequency estimates were interpolated to produce
continuous grids with grid-cell spacing of 2,000 meters. Contour
lines derived from these surfaces (grids) were used to produce
the maps in the "Depth-Duration Frequency of Precipitation for
Oklahoma" by R.L. Tortorelli, Alan Rea, and W.H. Asquith, U.S.
Geological Survey Water-Resources Investigations Report 99-4232.
Depth-duration-frequency estimates and interpolated surface
values are included in the point attribute tables. One
geospatial data set is provided for each of the 12 durations.

本套地理空间数据集收录了用于俄克拉荷马州区域降水频率分析的雨量站相关数据。

数据集取自俄克拉荷马州境内及毗邻州境内延伸约50公里的区域内、观测记录时长不少于10年的雨量站。本次研究采用三类雨量站网的数据，分别对应15分钟、1小时和1天的观测频次。研究针对7种重现期（分别为2年、5年、10年、25年、50年、100年及500年）与12种降雨历时（15分钟、30分钟、60分钟；1小时、2小时、3小时、6小时、12小时、24小时；1天、3天、7天）开展了数据分析。基于各站点的观测数据，针对每种降雨历时分别计算年最大降水量（水深）：其中110个15分钟观测站对应15、30、60分钟历时，141个小时雨量站对应1、2、3、6、12、24小时历时，413个日雨量站对应1、3、7天历时。

研究采用统计方法估算各站点对应每种历时-重现期组合的降水量水深。随后将各站点的历时-重现期降水量估算值通过插值处理，生成网格间距为2000米的连续空间格网。基于这些格网表面生成的等值线，用于绘制R.L. Tortorelli、Alan Rea与W.H. Asquith所著、美国地质调查局《水资源调查报告99-4232》中的《俄克拉荷马州降水历时-频率深度分布图》。

点属性表中包含了历时-重现期降水量估算值与插值得到的格网表面数值。本数据集集合为12种降雨历时分别提供一套地理空间数据。