Monthly aggregated Water Vapor MODIS MCD19A2 (1 km): Long-term data (2000-2022)

This data is part of the Monthly aggregated Water Vapor MODIS MCD19A2 (1 km) dataset. Check the related identifiers section on the Zenodo side panel to access other parts of the dataset.
General Description
The monthly aggregated water vapor dataset is derived from MCD19A2 v061. The Water Vapor data measures the column above ground retrieved from MODIS near-IR bands at 0.94μm. The dataset time spans from 2000 to 2022 and provides data that covers the entire globe. The dataset can be used in many applications like water cycle modeling, vegetation mapping, and soil mapping. This dataset includes:

Monthly time-series:Derived from MCD19A2 v061, this data provides a monthly aggregated mean and standard deviation of daily water vapor time-series data from 2000 to 2022. Only positive non-cloudy pixels were considered valid observations to derive the mean and the standard deviation. The remaining no-data values were filled using the TMWM algorithm. This dataset also includes smoothed mean and standard deviation values using the Whittaker method. The quality assessment layers and the number of valid observations for each month can provide an indication of the reliability of the monthly mean and standard deviation values.
Yearly time-series:Derived from monthly time-series, this data provides a yearly time-series aggregated statistics of the monthly time-series data.
Long-term data (2000-2022):Derived from monthly time-series, this data provides long-term aggregated statistics for the whole series of monthly observations.
Data Details

Time period: 2000–2022
Type of data: Water vapor column above the ground (0.001cm)
How the data was collected or derived: Derived from MCD19A2 v061 using Google Earth Engine. Cloudy pixels were removed and only positive values of water vapor were considered to compute the statistics. The time-series gap-filling and time-series smoothing were computed using the Scikit-map Python package.
Statistical methods used: Four statistics were derived: standard deviation, percentiles 25, 50, and 75.
Limitations or exclusions in the data: The dataset does not include data for Antarctica.
Coordinate reference system: EPSG:4326
Bounding box (Xmin, Ymin, Xmax, Ymax): (-180.00000, -62.00081, 179.99994, 87.37000)
Spatial resolution: 1/120 d.d. = 0.008333333 (1km)
Image size: 43,200 x 17,924
File format: Cloud Optimized Geotiff (COG) format.
Support
If you discover a bug, artifact, or inconsistency, or if you have a question please use some of the following channels:

Technical issues and questions about the code: GitLab Issues
General questions and comments: LandGIS Forum
Name convention
To ensure consistency and ease of use across and within the projects, we follow the standard Open-Earth-Monitor file-naming convention. The convention works with 10 fields that describes important properties of the data. In this way users can search files, prepare data analysis etc, without needing to open files. The fields are:

generic variable name: wv = Water vapor
variable procedure combination: mcd19a2v061.seasconv = MCD19A2 v061 with gap-filling algorithm
Position in the probability distribution / variable type: m = mean | sd = standard deviation | n = number of observations | qa = quality assessment
Spatial support: 1km
Depth reference: s = surface
Time reference begin time: 20000101 = 2000-01-01
Time reference end time: 20221231 = 2022-12-31
Bounding box: go = global (without Antarctica)
EPSG code: epsg.4326 = EPSG:4326
Version code: v20230619 = 2023-06-19 (creation date)

本数据集隶属于按月聚合的MODIS MCD19A2（1千米）水汽数据集，可通过Zenodo侧边栏的相关标识符板块获取该数据集的其他分卷内容。

## 数据集概况
本按月聚合水汽数据集源自MCD19A2 v061版本。水汽数据为通过MODIS近红外0.94μm波段反演得到的地表上方大气柱水汽含量。数据集时间跨度为2000年至2022年，覆盖全球范围，可应用于水循环建模、植被制图、土壤制图等诸多场景。本数据集包含以下内容：

### 月度时间序列数据
本数据源自MCD19A2 v061版本，提供2000年至2022年每日水汽时间序列数据的月度聚合均值与标准差。仅将有效无云的正像素值纳入统计以计算均值与标准差，剩余无数据值通过TMWM算法完成填充。本数据集同时包含使用Whittaker方法平滑得到的均值与标准差结果。质量评估图层与各月度有效观测点数可用于表征月度均值与标准差结果的可靠性。

### 年度时间序列数据
本数据源自月度时间序列数据，提供月度时间序列数据的年度聚合统计结果。

### 长期数据（2000-2022年）
本数据源自月度时间序列数据，提供全时段月度观测数据的长期聚合统计结果。

## 数据详情
1. 时间范围：2000年—2022年
2. 数据类型：地表上方大气柱水汽含量（单位：0.001厘米）
3. 数据采集与衍生方式：基于MCD19A2 v061版本，通过谷歌地球引擎（Google Earth Engine）衍生得到。移除云覆盖像素，仅保留水汽的正值用于统计计算。时间序列间隙填充与平滑处理通过Scikit-map Python工具包完成。
4. 所用统计方法：共衍生得到四类统计量：标准差、25%、50%、75%分位数。
5. 数据局限性与排除范围：本数据集未包含南极洲区域的数据。
6. 坐标参考系统：EPSG:4326
7. 边界框（最小经度、最小纬度、最大经度、最大纬度）：(-180.00000, -62.00081, 179.99994, 87.37000)
8. 空间分辨率：1/120度 = 0.008333333（即1千米）
9. 图像尺寸：43200 × 17924
10. 文件格式：云优化GeoTIFF（Cloud Optimized Geotiff，COG）格式。

## 技术支持与反馈
若您发现数据存在错误、异常或不一致之处，或有相关疑问，请通过以下渠道反馈：
- 代码相关技术问题与疑问：GitLab Issues板块
- 通用疑问与意见反馈：LandGIS论坛

## 命名规范
为确保项目内部与跨项目间的命名一致性与易用性，本数据集遵循Open-Earth-Monitor标准文件命名规范。该规范包含10个字段，用于描述数据的关键属性，使用者可无需打开文件即可实现文件检索、数据分析准备等操作。各字段说明如下：
1. 通用变量名：wv = 水汽（Water vapor）
2. 变量与处理流程组合：mcd19a2v061.seasconv = 搭载间隙填充算法的MCD19A2 v061版本数据
3. 概率分布位置/变量类型：m = 均值 | sd = 标准差 | n = 有效观测点数 | qa = 质量评估
4. 空间支撑分辨率：1km
5. 深度参考：s = 地表
6. 时间参考起始时间：20000101 = 2000-01-01
7. 时间参考结束时间：20221231 = 2022-12-31
8. 覆盖范围：go = 全球（不含南极洲）
9. EPSG代码：epsg.4326 = EPSG:4326
10. 版本代码：v20230619 = 2023-06-19（数据集创建日期）