Contents:Algorithm DescriptionScientific Data SetsLocal AttributesGlobal AttributesQuality Assurance |
MOD11B1 Daily LSTThe daily level 3 LST product at 5km spatial resolution is a tile of daily LST product gridded in the Integerized Sinusoidal projection. A tile contains 240 by 240 grids in 240 rows and 240 columns. The exact grid size at 5km spatial resolution is 4.64km by 4.64km.Algorithm DescriptionThe daily MOD11B1 LST product is constructed with the results produced by the day/night LST algorithm (Wan and Li, 1997). New refinements implemented in the V4 LST processing include: updating the look-up tables (LUT) used in the day/night LST algorithm, processing inland water pixels in clear-sky when cloud mask reports a clear confidence of 66% and higher, using the 5km resolution MODIS 16-day BRDF Albedo Parameters product (MOD43B1C) as input, separating the range of viewing zenith angles into five sub-ranges (0-24, 24-38, 38-49, 49-58, and 58-65 degrees) instead of four in V3, parallelly processing data in odd and even days to double the production rate and the storage of interim results (for two sets of day and night observations in each view angle sub-range) for the day/night algorithm, incorporating a split-window method into the day/night algorithm to ensure that the retrieved emissivities can be used by split-window algorithms, and supporting for the SIN grid. These refinements and better qualities of input products improve the V4 MODIS LST products significantly.The day/night LST algorithm in both V3 and V4 processings only uses those day and night MODIS observations: the day observations with solar zenith angle not larger than 75 degrees and the night observations with solar zenith angle larger than 90 degrees (i.e., no solar radiation in the night observations). It should be noted that a new constraint was added to the day/night LST algorithm in the V4 code: the time difference between the day and night observations cannot be longer than 32 days. This constraint significantly limits the LST/emissivity retrieval in the polar regions. Scientific Data Sets (SDS)The SDSs in the MOD11B1 product include LST_Day_5km, QC_Day, Day_view_time, Day_view_angl, LST_Night_5km, QC_Night, Night_view_time, Night_view_angl, Emis_20, Emis_22, Emis_23, Emis_29, Emis_31, Emis_32, LST_Day_5km_Aggregated_from_1km and LST_Night_5km_Aggregated_from_1km. The last two SDSs are used for global browse imagery. Their details are shown in Table 14.Table 14. The SDSs in the MOD11B1 product.
* In V4, a negative sign before the zenith view angle indicates that the MODIS views the Earth surface from east. ** The first four bits (00-03) are used as nighttime view angle flag to show the index of view angle sub-range of the nighttime observation used in the emissivity retrieval. Other four bits (04-07) are used as daytime view angle flag to show the index of the daytime view angle sub-range. The view angle sub-range index has a value of 0, 1, 2, 3, or 4, indicating the view angle in sub-ranges 0-24, 24-38, 38-49, 49-58, or 58-65 degrees. Local AttributesThe local attributes for SDSs LST_Day_5km and LST_Night_5km are similar to those in Table 4.Global AttributesThree ECS global attributes and 16 product-specific global attributes are stored as metadata. The ECS global attributes, CoreMetadata.0, ArchiveMetadata.0 and StructMetadata.0 are stored as very long character strings in PVL format.CoreMetadata.0 contains information about the product during production and is used to populate the EOSDIS data base for user support. They are similar to those of MOD11A1. Quality AssuranceThe bit flags defined for the quality assurance SDSs QC_day and QC_Night in MOD11B1 are listed in Table 15.Table 15. Bit flags defined for SDSs QC_day and
QC_Night in MOD11B1. Note that bit 0 is the least significant bit.
B - in V4
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