Using NUCAPS profiles before Pyrocumulus events

September 11th, 2022 |
GOES-17 True-color imagery, 2101 UTC 10 September to 0106 UTC on 11 September

A CSPP Geosphere mp4 animation from late on 10 September, above (link), shows the development of a pyrocumulus cloud at the south edge of the Cedar Creek fire complex in Oregon (previously discussed here, here and here). The animation above starts at 2101 UTC, shortly after a NOAA-20 overpass above the region. NUCAPS profiles over the regions can define the thermodynamics to help forecasters determine is pyrocumulus clouds might develop. The Green points in the sounding availability plots, below, denote retrievals that converged to a solution using both microwave and infrared data from the ATMS and CrIS instruments, respectively. This includes the profiles near the very warm Cedar Creek fire pixels in east-central Oregon. (Here is a zoomed-in view over the fire with GOES-17 FDCA Fire Power observations; note the two different regions of active fire).

GOES-17 Band 7 (3.9 µm) imagery at 2020 UTC on 10 September 2022 along with NUCAPS Sounding Availability plots (Click to enlarge)

The animation below steps through 3 NUCAPS profiles near the fire. A dry atmosphere is apparent, but note also the very steep lapse rates. If convection develops, aided by the heat of the fire, there is little to inhibit its growth to the tropopause.

NUCAPS profiles east, over and west of the Cedar Creek fire, ca. 2050 UTC on 10 September 2022 (Click to enlarge)

NUCAPS profiles can be gridded to provide horizontal fields of thermodynamic variables. The lapse rate computed from 850 and 500 mb temperatures, below, also shows very steep lapse rates (note that portions of Oregon are at/above 850 mb and no data are available).

GOES-17 Band 7 (3.9 µm) imagery along with NUCAPS gridded lapse rates (850-500 mb), ca. 2030 UTC on 10 September 2022 (Click to enlarge)

One things that happens when a Pyrocumulus develops: the cloud is trackable (in contrast to any surrounding smoke). The CSPP Geosphere animation below (link) shows the Night Microphysics (at night) and True-Color (during the day) — the cloud can be tracked until is dissipates near dawn, and the true-color imagery the next day shows the smoke associated with the pyrocumulus has also moved to the east. Note also in the animation how the active fires show up in the GOES-17 Night Microphysics as different shades of magenta.

Hourly imagery from CSPP Geosphere, 2206 10 September 2022 – 1706 UTC on 11 September 2022

Although infrared imagery is challenged to view smoke at night, as suggested in the animation above, the VIIRS Day Night band sees it (if there is sufficient illumination by the Moon). That was the case early on 11 September, as shown below (in an image taken from the VIIRS Today website). Both the light signature from fires are apparent as is the smoke plume from the pyrocumulus.

NOAA-20 Day Night Band visible (0.7 µm) imagery over Oregon, ca. 1100 UTC on 11 September 2022 (click to enlarge)

AWIPS Satellite imagery in this blog post were created using the TOWR-S AWIPS. Thank you!

Using CSPP Quicklooks software to show multiple NUCAPS passes

August 31st, 2022 |
Suomi-NPP NUCAPS estimates of 300-mb temperature, 15-20 October 2018 (click to enlarge)

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:

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 15o N, 75o W on a Lambert Conformal grid. Similarly, an image that uses all data from 20181919* can be created, as shown below.

Suomi-NPP NUCAPS profiles temperatures at 300 mb, ca. 1700 UTC on 19 October 2018 (Click to enlarge)
Suomi-NPP NUCAPS profiles temperatures at 300 mb, ca. 1900 UTC on 19 October 2018 (Click to enlarge)

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.

Anomalously-deep upper low brings light snow to northwestern Alaska

July 19th, 2022 |

GOES-18 Mid-level (6.9 µm) Water Vapor images, with plots of hourly surface weather type [click to play animated GIF | MP4]

GOES-18 images shown in this blog post are preliminary and non-operational

GOES-18 Mid-level Water Vapor (6.9 µm) images during the 18 July – 19 July 2022 period (above) showed a series of impulses rotating within the broader circulation of an anomalously-deep low pressure system that meandered over the Bering Strait region. Anomalously-cold air associated with this deep low helped to produce brief periods of unusual July snow at some locations across the Seward Peninsula and northwestern Alaska.

In GOES-18 Air Mass RGB images created using Geo2Grid (below), brighter shades of red highlighted the core of this broad low pressure system, where high-altitude ozone levels were elevated (due to an unusually low tropopause).

GOES-18 Air Mass RGB images [click to play animated GIF | MP4]

Plots of rawinsonde data at Nome, Alaska at 00 UTC and 12 UTC on 19 July 2022 [click to enlarge]

In fact, at 12 UTC on 19 July the low 500 hPa geopotential height value of 5269.3 meters from the Nome, Alaska rawinsonde report (above) established a new July record for that site. The 12 UTC sounding also suggested that the tropopause was located at an unusually low pressure level of 483 hPa — such a low tropopause height was supported by NOAA-20 Gridded NUCAPS data from the SPoRT site (below).

NOAA-20 Gridded NUCAPS Tropopause Height at 1236 UTC on 19 July [click to enlarge]

Himawari-8 and NUCAPS observations of an upper-level feature in the western Pacific

July 13th, 2022 |
ABI Sandwich Product (Day TIme) and Band 13 (10.41 µm, night time) from 0000 UTC on 10 July 2022 through 2350 UTC on 12 July 2022 (Click to enlarge)

Himawari-8 Imagery, above (courtesy JMA, the Japan Meteorological Agency, from this site), shows a cyclonically rotating feature over the western Pacific, approaching the northern Marianas Islands by the end of the animation. Periodic weak convection is forming within the center of the circulation, with more widespread convection developing to its east. Gridded NUCAPS fields, below, from this site, show that the cyclonic feature is associated with relatively cool temperatures at 500 mb. At the beginning of the animation, the cool temperatures are near Wake Island; the cool temperatures progress steadily westward just south of 20o N latitude over the following days and are over the Marianas at the end of the animation.

Gridded NUCAPS estimates of 500-mb temperatures, 09-13 July 2022 (click to enlarge)

Examination of surface-based winds (from scatterometers, at this site) suggests that the mid-level circulation does not extend all the way to the surface.

Update, 14 July 2022

By 0333 UTC on 14 July 2022, the cool region at 500 mb was centered just west of 20oN, 150oE. (Its westward progress has slowed significantly) The cool region overlaps a ‘green’ Quality Control Region, meaning the retrieval there converged to a solution. Yellow regions likely correspond with clouds, and the infrared retrieval did not converge (but the microwave one did); red points depict a lack of convergence in the infrared and microwave retrievals. For more information on the retrieval, check out this training video on NUCAPS profiles.

Gridded NUCAPS field of 500-mb Temperature, and NUCAPS Quality Control Flag, 0333 UTC on 17 July 2022 (Click to enlarge)

Did the cold pool aloft have a surface signature? Scatterometry overlain on top of Himawari-8 Visible (0.64 µm) imagery, along with a streamline analysis from the NOAA/NWS/NCEP Global Forecasting System (GFS) model, shown below (courtesy Brandon Aydlett, WFO Guam), shows anticyclonic flow underneath the region of the upper-level cold pool. Upper-level (300-mb) streamline (shown here overlain on top of Himawari-8 Upper Level water vapor imagery (Band 8, 6.24 µm), also courtesy Brandon Aydlett) shows an upper-level cyclonic circulation associated with the cold pool.

Himawari-8 Visible Imagery (0.64 µm) at 0140 UTC, ASCAT observations (0130-0300 UTC), and GFS Surface Streamlines (3-h forecast valid 0300 UTC), all on 14 July 2022 (click to enlarge)