Albedo Retrievals from MODIS Over the Sea of Okhotsk (Validation Data, 2002–2014)

This dataset contains satellite-based albedo retrievals and surface classifications from MODIS sensors over the Sea of Okhotsk, collected during multiple voyages of the Soya Icebreaker from 2002 to 2014. The dataset focuses on validating MODIS retrievals by comparing them to in-situ albedo measurements collected by the Soya Icebreaker. The retrieval data is standardized on a 1-km grid and includes albedo and surface classification values for each available time period. Only satellite retrievals were uploaded, without the in-situ measurements.Key features of this dataset include:• Albedo retrieval data using the retrieval algorithm is described in https://doi.org/10.5194/tc-17-1053-2023.<br>• Surface classification masks indicating different surface types (e.g., land, water, snow-covered ice).The dataset was used to analyze and quantify the discrepancies between satellite-based retrievals and in-situ measurements under varying conditions of sea ice, snow, and meltwater, and to understand the impacts of time differences between satellite overpasses and ground-based measurements.Variables:1. SW:<br>Shortwave albedo values retrieved from the MODIS sensor using the SciML albedo retrieval algorithm. The retrievals were made over the Sea of Okhotsk region, focusing on the validation period (2002–2014).<br>2. mask:<br>Surface classification mask for the MODIS sensor. This mask classifies each grid point based on surface type:<br>• 0: Invalid<br>• 1: Land<br>• 2: Water<br>• 3: Snow on land<br>• 4: Bare Sea-ice<br>• 5: Snow-covered Sea Ice<br>• 6: Cloud/Fog (nullified)<br>Time Periods:<br>The dataset spans the following time periods, during which MODIS data was validated against in-situ measurements:• 2002-02-14<br>• 2002-02-16<br>• 2003-02-06<br>• 2003-02-07<br>• 2003-02-11<br>• 2004-02-07<br>• 2004-02-08<br>• 2004-02-09<br>• 2004-02-10<br>• 2006-02-12<br>• 2007-02-10<br>• 2008-02-09<br>• 2008-02-10<br>• 2008-02-11<br>• 2009-02-10<br>• 2013-02-25<br>• 2013-02-26<br>• 2014-02-15<br>Spatial Coverage:• Latitude: 43.5° to 46° N (region where Soya Icebreaker operated)<br>• Longitude: 141° to 146° E<br>Format:The data is provided in NetCDF format (.nc), with dimensions for date, latitude, and longitude. Each time step corresponds to a specific satellite overpass date, and the spatial data are aligned to a grid covering the Sea of Okhotsk.Usage:This dataset is intended for validating MODIS satellite retrievals against ground-based measurements, particularly for studying discrepancies in albedo measurements under different ice and snow conditions.<br>

本数据集包含鄂霍次克海(Sea of Okhotsk)区域基于MODIS传感器（MODIS）的反照率反演结果与地表分类数据，采集自2002年至2014年间“宗谷号”破冰船(Soya Icebreaker)的多次科考航行。本数据集的核心目标是通过将MODIS反演结果与“宗谷号”采集的原位反照率测量数据进行对比，以验证MODIS反演产品的准确性。反演数据已标准化至1公里网格，涵盖各有效时段的反照率与地表分类数值。本数据集仅上传卫星反演结果，未包含原位测量数据。

本数据集的主要特征包括：
• 采用指定反演算法生成的反照率反演数据，相关算法详细说明见https://doi.org/10.5194/tc-17-1053-2023。
• 地表分类掩码，用于标识不同地表类型（例如陆地、水体、积雪覆盖冰面等）。

本数据集被用于分析、量化不同海冰、积雪与融水条件下卫星反演结果与原位测量数据之间的偏差，并探究卫星过境与地面测量之间的时间差对结果的影响。

### 变量说明
1. SW：
采用SciML反照率反演算法从MODIS传感器反演得到的短波反照率数值，反演区域覆盖鄂霍次克海，聚焦于2002–2014年的验证时段。
2. mask：
MODIS传感器对应的地表分类掩码，该掩码依据地表类型对每个网格点进行分类：
• 0：无效值
• 1：陆地
• 2：水体
• 3：陆地积雪
• 4：裸露海冰
• 5：积雪覆盖海冰
• 6：云/雾（无效值）

### 时间覆盖时段
本数据集覆盖以下时段，在此期间MODIS数据曾与原位测量数据进行验证比对：
• 2002-02-14
• 2002-02-16
• 2003-02-06
• 2003-02-07
• 2003-02-11
• 2004-02-07
• 2004-02-08
• 2004-02-09
• 2004-02-10
• 2006-02-12
• 2007-02-10
• 2008-02-09
• 2008-02-10
• 2008-02-11
• 2009-02-10
• 2013-02-25
• 2013-02-26
• 2014-02-15

### 空间覆盖范围
• 纬度：43.5°N至46°N（“宗谷号”破冰船的科考作业区域）
• 经度：141°E至146°E

### 数据格式
数据以NetCDF格式（.nc）提供，包含日期、纬度、经度三个维度。每个时间步对应一次卫星过境的具体日期，空间数据对齐至覆盖鄂霍次克海的网格。

### 数据用途
本数据集旨在将MODIS卫星反演结果与地面原位测量数据进行验证比对，尤其适用于研究不同冰雪条件下反照率测量结果的偏差情况。