NOAA Office of Satellite and Product Operations

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LTOAST product using S-NPP OMPS Limb Profiler and S-NPP CrIS NUCAPS

Current LTOAST Analysis
(Click image to enlarge Latest LTOAST image)

Southern Hemisphere View   |    Northern Hemisphere View

Information provided by Jianguo Niu (STAR)

The LTOAST algorithm produces another flavor of IR and UV/Vis blended TOAST ozone products. It blends the ozone products from the UV/Vis sensor OMPS Limb Profiler and the Infrared sensor CrIS (NUCAPS) onboard the S-NPP satellite. The CrIS (NUCAPS) analysis algorithm providing the IR ozone profiles in LTOAST is the same one used in NTOAST. The difference between LTOAST and NTOAST is that they are using different UV/Vis sensors. NTOAST uses the OMPS Nadir Profiler V8Pro ozone profiles, LTOAST uses the OMPS Limb Profiler V2Limb ozone profiles. Because of the specific observing geometry, the Limb does not obtain ozone profiles extending into the lower troposphere. As a result, LTOAST does not provide a total column analysis for the Limb sensor. The current LTOAST provide analyzed 1° by 1° ozone maps in twelve Umkehr layers for UV/Vis and IR data products separately.

To achieve this, both the V2Limb and NUCAPS profiles are reformed into 12 Umkehr layers products by interpolating their individual profiles of 60 layers in V2Limb and 100 layers in NUCAPS. In this profile reorganization, the surface pressure and data quality flags are included. All 12 layers for V2Limb and NUCAPS are then projected from their geographic coordinate onto a stereographic projection map in two hemispheres. Within these two projection maps, an objective analysis is conducted by using the current observations to adjust initial guesses (previous day’s maps). After the analysis, the data are converted back to the geographic coordinate. Both LTOAST and NTOAST blended products are a simple combination with mid to upper stratosphere (MSUS) ozone for LTOAST from V2Limb and for NTOAST from V8Pro, and the full troposphere and lower stratosphere (FTLS) ozone from NUCAPS. In practice, the MSUS ozone is defined as the integration of the upper eight layers of the 12-Umkehr layer UV-/Vis profile (LTOAST from V2Limb, NTOAST from V8Pro). The FTLS is defined as the lower four layers in the 12-LUmkehr IR layer profile (both LTOAST and NTOAST are from NUCAPS).