Daily cloud-gap-filled Terra–Aqua MODIS NDSI dataset over High Mountain Asia (2000-2024)

<p>1. The daily cloud-gap-filled (CGF) MODIS normalized difference snow index (NDSI) dataset over High Mountain Asia (HMA) (2000-2024) is generated by combining of the cubic spline interpolation (CSI) method and the Spatio-Temporal Weighted (STW) method. This dataset is derived from daily 500 m MOD10A1 (Terra) and MYD10A1 (Aqua) products.</p> <p>2. The cloud persistence days (CPD) dataset is also provided. The CPD represents the number of consecutive days of cloud observed for a pixel from the last cloud-free observation to the next cloud-free observation. And the CPD is used to determine the combination of CSI and STW method, which is expressed as: when CPD &lt; 8 d, the CSI method is used; when CPD &ge; 8 d, the STW is used.</p> <p>3. The CGF MODIS NDSI dataset is provided in ENVI standard format (.img) and the CPD dataset is provided in Geotiff format. And they are all provided in a geographic projection using the WGS84 coordinate system at a 0.005&deg; (about 500 m) resolution. The NDSI value ranges from 0~100 and the CPD value ranges from 0~366. The fill value of both dataset is set to 255 (outside the track coverage of MODIS product).</p> <p>4. The CGF MODIS NDSI dataset contains 25 compressed packages (named after the normal year) of the daily CGF MODIS NDSI dataset over HMA (2000-2024), and after uncompressing the files are named as &ldquo;YYYYDDD_HMA_MODIS_NDSI_0.5km.img&rdquo;. The CPD dataset contains 25 compressed packages (named after the normal year) of the daily CPD dataset over HMA (2000-2024), and after uncompressing the files are named as &ldquo;YYYYDDD_CPD.tif&rdquo;. The YYYY represents the year and the DDD represents Julian day (001-365/366).</p> <p>5. The accuracy of this dataset has been well evaluated based on in-situ snow depth (SD) observations and high-resolution snow cover maps derived from Landsat images. The detailed information can be found in the paper (Deng, G., Tang, Z., Dong, C., Shao, D., &amp; Wang, X. (2024). Development and Evaluation of a Cloud-Gap-Filled MODIS Normalized Difference Snow Index Product over High Mountain Asia.&nbsp;<em>Remote Sensing</em>,&nbsp;<em>16</em>(1), 192. https://doi.org/<a href="https://doi.org/10.3390/rs16010192">10.3390/rs16010192</a>).</p>