GOES-R Satellites include GOES-16 (the present GOES-East), GOES-17 and GOES-18 (both scanning as GOES-West), and GOES-U, which will become GOES-19 after achieving geostationary orbit after launch (scheduled to occur in 2024). The follow-on to the GOES-R Series is GeoXo (Geostationary Extended Observations), with a launch planned in the 2030s. The GeoXo Imager, GXI, will improve on capability of GOES-R’s Advanced Baseline Imager (ABI). (See this announcement for development of the instrument) One of the channels that might be on this new imager will take observations at/around 5.1 µm. Why was this band chosen? And which present-day instruments can give observations at/near that wavelength to demonstrate that band’s utility?

The Cross-Track Infrared Sounder (CrIS) on NOAA-20 and Suomi-NPP is a Fourier transform spectrometer that provides 2000+ observations in 3 different wavelength ranges: Shortwave infrared (SWIR, 3.92- 4.64 ?m), mid-wave infrared (MWIR, 5.71-8.26 µm) and longwave infrared (LWIR, 9.14-15.38 µm). The toggle above compares 5.71 µm and 7.3 µm observations (wavenumbers 1755 and 1370) from five CrIS granules on 15 August 2022. Note how much warmer the 5.71 µm brightness temperatures are compared to the 7.3 µm brightness temperatures over northeast Mississippi (for example). The shorter wavelength observation are viewing features closer to the boundary layer.

A toggle of GOES-16 imagery and derived products for the same time is shown below. Strong instability (via the Derived Stability Lifted Index) and moisture (from the TPW field) are indicated in a region where the upper troposphere is dry (the 1200 UTC sounding on 15 August at Jackson MS shows considerable mid-level instability, although the SPC Outlook for that day showed only General Thunder.)

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This paper (from the AMS Annual Meeting in 2021) explored some of the issues in using 5.1 µm. A strength of observations at this wavelength is that it lies in a region where absorption (and therefore cooling in the observations) by CO₂ is minimal, and where absorption by water vapor in increasing (absorption by water vapor is much stronger for wavelengths between 5.5 µm and 7.5 µm)

This poster from the Collective Madison Meeting of the American Meteorological Society (in 2022) includes weighting function figures for 5.1 µm in various atmospheres, as shown below. In all atmospheres, a significant portion of the signal is coming from the surface. Compare these weighting functions to, for example, the 7.3 µm (“Low-level Water Vapor”, Band 10) for Tropical and US Standard atmospheres: very little surface information is present in observations at 7.3 µm. (See also the CIMSS weighting function website for ABI channels) The conclusion: observations at 5.1 µm can give more information about the water vapor distribution in the boundary layer than present-day water vapor channels on ABI. (See also this paper by Miller et al.)

The IASI instrument on MetopB/MetopC does take observations at 5.1 µm. Stay tuned for a blog post using those observations. Thanks to Mat Gunshor, CIMSS, and Tim Schmit, NOAA/STAR, for enlightening discussions about the 5.1 µm observations.

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GeoXo is also slated to carry a hyperspectral sounder (GXS). Sounders give far more complete assessments of the state of the atmosphere than an imager, even an advanced one like GXI!

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The International Space Station carries a variety of instruments, including the Lightning Imaging Sensor (LIS), designed to extend the Lightning Climatology from the Tropical Rainfall Measuring Mission (TRMM). ISS overflew Typhoon Hinnamnor at about 1540 UTC on 1 September (image, from this site). The lightning animation above (click here for an animated gif) shows data from 1539 UTC until 1543 UTC, with >80 flash events occurring.  The observed lightning is far from the ragged eye of the storm.

The Joint Typhoon Warning Center (link) and the Japan Meteorological Agency (link) have more information on this typhoon.  Previous blog posts on Hinnamnor are here and here.  Himawari-8 data are courtesy JMA.

 

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2.5-minute rapid scan JMA Himawari-8 Visible (0.64 µm) images (above) showed rapidly-intensifying Typhoon Hinnamnor as it once again reached Category 5 intensity (ADT | AiDT | SATCON) about 3 hours after local sunrise on 31 August 2022. Mesovortices rotating within the eye were evident though breaks in patchy high clouds overhead.

2.5-minute Himawari-8 Infrared (10.4 µm) images (below) revealed convection within the eyewall region which exhibited cloud-top infrared brightness temperatures of -80°C and colder (violet pixels).

Several hours before sunrise, a toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images valid at 1749 UTC, viewed using RealEarth (below) revealed concentric mesospheric airglow waves in the DNB image, propagating away from Hinnamnor (primarily to the north of the storm).

The mesospheric airglow waves were less evident in an earlier comparison of Suomi-NPP VIIRS Day/Night Band and Infrared Window images, valid at 1700 UTC (below) — however, at that time the DNB displayed bright streaks near the eye, indicative of clouds illuminated intense lightning activity.

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CSPP Quicklooks (click to view documentation) is a software package (available here) developed at CIMSS to (as the name might suggest!) create images from Polar-orbiting data, as shown in this blog post that shows imagery created from Direct Broadcast data (for example. using NUCAPS EDRs (Environmental Data Records) files as available at the CIMSS Direct Broadcast site). NUCAPS EDR files can also be downloaded from the NOAA CLASS site — by choosing ‘JPSS Sounder Products’ in the ‘Please select a product to search’ drop-down menu, and then choosing ‘NUCAPS Environmental Data Records’ — that is, EDRs.

Follow the instructions in this blog post to download and set up the Quicklooks software (free registration at the CSPP website may be required). Imagery at the previous blog post used default domains and colorbars. In the example above, multiple images are captured over a specified domain, and are scaled identically using keywords as shown in the calls below:

file18=$CSPP_SOUNDER_QL_HOME/data4/NUCAPS-EDR_v2r0_npp_s2018101917*.nc
sh ./ql_level2_image.sh "$file18" NUCAPS --dset temp --pressure 300 --plotMin 223.0 --plotMax 258.0 --lat_0 15.0 --lon_0 -75.0

Note that ‘file18’ identifies all files within a directory that contain an EDR from around 1700 UTC on 19 October 2018. The wildcard includes >20 different granules that are composited into an image for that time, as shown below. The –plotMin and –plotMax keywords define the color scaling used, and the data are centered at 15^o N, 75^o W on a Lambert Conformal grid. Similarly, an image that uses all data from 20181919* can be created, as shown below.

How are both images combined so that data from the afternoon/evening passes are in one image (as shown in the animation above?) This is done by making parts of the images above transparent, and by overlaying the transparent image over the bottom image (I did this using ImageMagick). Both white (“#ffffff”) and grey (“#d9d9d9”) values were made transparent, and a combined image (here) is created. This is done for all morning images, and afternoon/evening images, and the animation is then created.

Note that if this is done when both Suomi-NPP and NOAA-20 passes are available, the gaps apparent in the imagey above will not be present. October 2018 was before NOAA-20 NUCAPS were operational however.

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