Baseflow adjusted snowmelt runoff and rainfall runoff from TerraClimate

We update the total runoff and runoff partitioned from snowmelt from TerraClimate using a modified water balance model that better accounts for baseflow lags in hydrology for use in basin level water supply availability at monthly time scales. These data complement existing TerraClimate 1-d water balance similations, but show much has improved montly correlative skill (median r=0.88) to observed streamflow across watersheds globally watersheds compared with the original method from TerraClimate (median r=0.75). These data can be used to quantify gaps in monthly water demand for downstream water uses including agriculture., The original TerraClimate (Abatzoglou et al., 2018) runoff data (q) assumed that all water (rain plus snowmelt, P) in excess of the additional soil water holding capacity (maximum soil water storage minus soil moisture or SR) and monthly evapotranspiration (ET) – or water surplus – immediately runs off that month. 
S = max(0, 0.95*P - ET-SR)
q = 0.05*P + S
While this water balance approach may be valid at local scales, the approach does not account for a variety of factors including baseflow contributions or stream routing and transit time. Some studies show that the transit time for runoff to reach a basin terminus is up to a month (Allen et al., 2018). We updated the approach for simulating runoff to account for the contributions of baseflow and transit time following Wolock and McCabe (1999). Specifically, half of the surplus generated each month becomes runoff while the remaining half is carried over as surplus to the following month. 
Supdate(month)=Supdate(month-1)+0.5*max(0, 0.95..., , # Baseflow adjusted snowmelt runoff and rainfall runoff from TerraClimate

[https://doi.org/10.5061/dryad.vx0k6dk2h](https://doi.org/10.5061/dryad.vx0k6dk2h)

## Description of the data and file structure

Input forcing of temperature, snow water equivalent, soil moisture, and precipitation comes from [TerraClimate ](https://www.nature.com/articles/sdata2017191)at a 1/24th degree resolution globally.

We use the runoff partitioning scheme from [Qin et al., (2020)](https://www.nature.com/articles/s41558-020-0746-8) to separate runoff from snowmelt from rainfall runoff.

The original TerraClimate runoff data (q) assumed that all water (rain plus snowmelt, P) in excess of the additional soil water holding capacity (maximum soil water storage minus soil moisture or SR) and monthly evapotranspiration (ET) – or water surplus – immediately runs off that month. 

TW = 

S = max(0, 0.95*P - ET-SR)

q = 0.05*P + S

While this water balance approach may be valid at local scales, the approach does ...

本数据集基于修正后的水平衡模型(water balance model)，对TerraClimate(TerraClimate)的总径流及融雪分割径流进行更新，该模型可更好地刻画水文过程中的基流(baseflow)滞时，适用于月尺度下的流域尺度供水可用性评估。
本数据集可补充现有TerraClimate一维水平衡模拟结果，相较于TerraClimate原方法（中位数相关系数r=0.75），其在全球流域的实测河道径流匹配上展现出更优的月尺度相关性能（中位数r=0.88）。该数据集可用于量化包括农业在内的下游用水的月需水缺口。

原始TerraClimate(Abatzoglou等人，2018)的径流数据（记为q）假定，所有超出额外土壤持水量（最大土壤储水量减去土壤湿度，即SR）与月蒸散发(Evapotranspiration, ET)之和的水量（降雨与融雪总量，记为P）——即水分盈余——会在当月立即产生径流。公式如下：
S = max(0, 0.95*P - ET - SR)
q = 0.05*P + S

尽管该水平衡方法在局地尺度具备一定合理性，但该方案未考虑基流贡献、河道汇流(stream routing)与汇流时间(transit time)等多项因素。已有研究表明，径流抵达流域出口的汇流时间最长可达一个月（Allen等人，2018）。本研究遵循Wolock与McCabe（1999）的方法，对径流模拟方案进行更新，以纳入基流贡献与汇流时间的影响。具体而言，当月产生的盈余水分有一半转化为径流，剩余一半则作为盈余结转至下月：
S_update(month) = S_update(month-1) + 0.5*max(0, 0.95*P - ET - SR)
（原文此处公式存在截断，保留原样）
# 经基流校正的TerraClimate融雪径流与降雨径流

[https://doi.org/10.5061/dryad.vx0k6dk2h](https://doi.org/10.5061/dryad.vx0k6dk2h)

## 数据与文件结构说明
本数据集的输入强迫场包括气温、雪水当量、土壤湿度与降水，源自全球分辨率为1/24度的TerraClimate数据集。
我们采用Qin等人（2020）提出的径流分割(runoff partitioning)方案，将融雪径流与降雨径流进行分离。
原始TerraClimate径流数据（q）假定，所有超出额外土壤持水量（最大土壤储水量减去土壤湿度，即SR）与月蒸散发(Evapotranspiration, ET)之和的水量（降雨加融雪，记为P）——即水分盈余——会在当月立即产生径流。
公式如下：
TW = （原文此处公式缺失，保留原样）
S = max(0, 0.95*P - ET - SR)
q = 0.05*P + S
尽管该水平衡方法在局地尺度具备一定合理性，但该方案未考虑……（原文此处内容存在截断）