Archive for the ‘NUCAPS’ Category

So, recently I’ve had the opportunity to use and evaluate soundings from the NOAA Unique Combined Atmospheric Processing System (NUCAPS).  These soundings, produced by the ATMS and CrIS instruments onboard the Suomi NPP satellite, are available in AWIPS generally twice per day over any given location.


Image 1.  NUCAPS Sounding data availability example, ~19 UTC 24 July 2016. Colors represent quality control flags — green are considered best available and most representative data.

A couple of advantages of the NUCAPS soundings is they’re available in relatively high spatial resolution (image 1) and also in between radiosonde launches.  So, a forecaster wanting to know more about tropospheric conditions during the midday or early afternoon (usually the most crucial period for severe weather analysis) can utilize NUCAPS sounding data, since radiosonde data won’t be available until later in the evening (unless ~18 UTC launches are being conducted at their location).  On a number of days in recent weeks, a lack of sufficient boundary layer moisture (probably partly due to an ongoing drought in the region) have dampened convective development.  A good understanding of the degree of convective inhibition (CIN) present on a given day can be difficult to obtain and model analyses and forecasts don’t always seem to have a good handle on this.  Even other robust analyses often struggle with a seemingly accurate depiction of CIN on many days.  However, knowledge of CIN, among other factors, can be important when forecasting probabilities for convective development on summer days.

Recently however, I’ve noticed that NUCAPS soundings did indicate the presence of CIN when convective development was perhaps less than expected or forecast.  July 20th was one of these days.  Take a look at the NAM Bufr Sounding for HSV, valid for 19 UTC on 20 July 2016 (image 2).


Image 2.  NAM Bufr Sounding for KHSV, 19 UTC 20 July 2016

The NAM Bufr model sounding indicated robust CAPE values (generally >2500 J/Kg) and little to no CIN.  Now, let’s take a look at a couple of nearby representative NUCAPS soundings (unfortunately, they don’t include the associated data tables).  Image 3 shows the locations of the NUCAPS soundings with respect to the KHSV observation site and the location in the NAM forecast sounding above (image 2).


Image 3.  NUCAPS Sounding locations for image 4…also, the KHSV location in northern Alabama


Image 4.  NUCAPS Soundings at 19 UTC for location A (left, west of KHSV) and location B (right, southwest of KHSV), 20 July 2016

Even though data tables are not shown from the NUCAPS soundings, notice that they indicate much less instability and less steep lapse rates than the NAM Bufr sounding prognostications for the same time (19 UTC).   Also, notice that LCL levels are below the LFC, indicating some amount of CIN at both locations.  If memory serves correctly, NUCAPS soundings indicated CIN values around 25-50 J/Kg at this time.  So, for a forecaster struggling with the likelihood/coverage of convective development and the strength of convective updrafts, the NUCAPS data would have suggested lesser magnitude for both, over the NAM progs.  Image 5 shows the general dearth of convective activity in the area of northern Alabama near 19 UTC that day.  And indeed, convection was generally limited through the afternoon, with mostly isolated, small cells present.


Image 5. Composite reflectivity (dBZ) at 1830 UTC 20 July 2016

When viewing the NUCAPS soundings, I’ve generally been looking for CAPE/CIN values while in the convective season.  Of course, having to click on a number of soundings can be a bit laborious.  As part of a JPSS Proving-Ground/Risk Reduction multi-organization project, researchers at CIMSS, CIRA, GINA and NASA SPoRT have developed gridded NUCAPS data, which were utilized in the Hazardous Weather Testbed this past spring.  I’ll be working with members of the SPoRT team to ingest those data in AWIPS II here at the HUN office in the near future for my own testing, evaluation and feedback to the NUCAPS group within the JPSS Proving Ground.  I’m looking forward to the future use and evaluation of these potentially useful operational data sets.

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Gridded NUCAPS products developed as part of a multi-organization JPSS PG/RR project are currently being evaluated at the Hazardous Weather Testbed (HWT) Experimental Warning Program (EWP).  The project contains contributions by researchers from UW/CIMSS, CSU/CIRA/ UAF/GINA, and SPoRT.  NUCAPS soundings are retrieved temperature and moisture soundings from the Suomi-NPP CrIS and ATMS sounders.  The evaluation of NUCAPS at HWT is aimed at providing upper air temperature and moisture information in the pre-convection environment to better understand variables that are necessary for convection and severe weather.  The Gridded NUCAPS products allows for isobaric plan views of temperature and moisture that forecasters can use to gain confidence in the model output

Forecasters at the HWT-EWP posted some input on the use of the Gridded NUCAPS products.  On the Satellite Proving Ground at HWT Blog (http://www.goesrhwt.blogspot.com/2016/04/nucaps-planviews.html), a forecaster noted:

“[Gridded NUCAPS] would be beneficial in the forecasting environment as added temperature data would be available in between standard upper-air launches.  This could serve as a good proxy to help judge the strength of a capping inversion, while also possibly serving as an additional information source during winter wx events.

However, the forecaster also noted that the amount of missing data included in the product limits its utility.  Currently, the Gridded NUCAPS contains only the highest quality (i.e., “best”) data that comes from a combination of both microwave and infrared (top image below).  In this image, the dark blue pixels represent the data that are discarded due to QC issues.  However, this quality control can be strict at times and leave out “good” data that can still be useful to the forecasters.  When these “good” data are included, there are much more useful data (bottom image below) without any noticeable discontinuities or oddities in the data.

SPoRT plans to use the feedback from HWT-EWP participants to test pushing the inclusion of the “good” quality data to the Gridded NUCAPS product to provide forecasters with more data for their analysis.


853 hPa Gridded NUCAPS temperature product from 21 April 2016 at 1902 UTC including only the highest quality flags.  Dark blue pixels denote discarded data that results in data gaps.  Note that a lot of over-land observations are discarded.


853 hPa Gridded NUCAPS temperature product from 21 April 2016 at 1902 UTC including both “best” and “good” quality flags.  Dark blue pixels denote discarded data.  Missing pixels generally correspond to thick cloud features.


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Over the last few days Himawari-8 AHI Air Mass RGB imagery has captured an impressive view of Severe Tropical Storm Choi-wan near Japan.  The storm began as a tropical depression near Wake Island and the Japan Meteorological Agency upgraded the depression to a tropical storm on October 2nd.  The tropical storm continued to move north-northwest toward Japan and the Sea of Okhotsh but weakened as it evolved.  Yesterday and today (October 8th) the storm began to take on more extratropical characteristics and look like a strong mid-latitude low pressure system (click on Fig. 1 animation).

Himawari-8 AHI Air Mass RGB 0000 UTC 6 October 2015 to2020 UTC 8 October 2015

Figure 1. Himawari-8 AHI Air Mass RGB 0000 UTC 6 October 2015 to2020 UTC 8 October 2015

Currently, SPoRT is investigating the utility of NOAA Unique CrIS/ATMS Processing System (NUCAPS) satellite retrieved soundings for hurricane tropical to extratropical transition events. Soundings are typically used to anticipate severe weather and analyze the pre-convective environment; however, they can be just as valuable for analyzing and understanding the environment surrounding complex extratropical transition events, especially over data sparse oceanic regions. National Center forecasters at the National Hurricane Center and Ocean Prediction Center routinely use the Air Mass RGB for forecasting such events, especially for identifying the influence of warm, dry stratospheric air during extratropical transition.  Although the Air Mass RGB provides a wealth of information about the upper-level horizontal distribution of temperature and moisture characteristics surrounding a storm, it does not provide insight about the vertical distribution of thermodynamic characteristics. With Next-Generation S-NPP/JPSS NUCAPS Soundings now available in AWIPS-II, they can be used in conjunction with the Air Mass RGB to anticipate extratropical transition events.

Here are a few examples of NUCAPS Soundings compared to the Air Mass RGB. Let’s take a look at NUCAPS Soundings in three locations in the environment surrounding Severe Tropical Storm Choi-wan (Fig. 2).

Himawari-8 AHI Air Mass RGB 1520 UTC 7 October 2015 capturing an impressive

Figure 2. Himawari-8 AHI Air Mass RGB 15:20 UTC 7 October 2015 capturing impressive view of Severe Tropical Storm Choi-wan near Japan and NUCAPS Sounding point locations (green dots) 1500 UTC

Location 1, red/orange coloring, represents upper-level dry air on the Air Mass RGB.  To no surprise, the NUCAPS Sounding (Fig. 3) reveals dry upper-levels and dry conditions throughout the atmospheric column.

NUCAPS Sounding 1500 UTC 7 October 2015 taken near label 1 in the Air Mass RGB in a region representative of upper-level dry air (orange coloring)

Figure 2. NUCAPS Sounding 1500 UTC 7 October 2015 taken near Location 1 in the Air Mass RGB(Fig. 2) in a region representative of upper-level dry air (red/orange color)

Now Location 2 is also in an orange colored region and representative of upper-level dry air, but take note the coloring is not as “red tinted” as Location 1 and there are more mid-level clouds.  Mid-level clouds tend to be light tan or ocher colored in the Air Mass RGB.  The NUCAPS Sounding (Fig. 3) does confirm a mid-level moisture layer from about 800-600 mb. Seeing ocher clouds in the RGB only means that qualitatively mid-level clouds are present (one can’t get a quantitative height from the RGB), but inspection of the NUCAPS Sounding would give a quantitative height estimate of the mid-level clouds.  Although this sounding is in the region right over the mid-level cloud, looking at more soundings in the same orange region (but not right over a cloud) do show the atmospheric column is not completely dry (like Location 1) but there is low- to mid-level moisture present throughout the region surrounding Location 2.  Just by looking at the RGB one may not realize a mid- to low-level moisture layer is present since the interpretation of the orange coloring in the Air Mass RGB is upper-level dry air.

NUCAPS Sounding

Figure 3. NUCAPS Sounding 1500 UTC 7 October 2015 taken near Location 2 in the Air Mass RGB (Fig. 2) in a region representative of upper-level dry air (orange coloring) and mid-level clouds (light orange or ocher color)

Location 3 is the most interesting (at least to me since the sounding gives more information about the atmosphere than one could extrapolate from just looking at the Air Mass RGB).  The green coloring around Location 3 represents a warm, moist air mass.  The NUCAPS Sounding (Fig. 4) does reveal a more moist sounding about 300 mb and above, but note there is mid-level dry air present and a low level moist layer.  Again the NUCAPS Soundings provide more information about mid- and low- level characteristics that one can’t infer from the RGB imagery.  This is just one example that highlights the utility of analyzing Next-Generation satellite data sets for complex weather events in data sparse regions.

NUCAPS Sounding

Figure 4. NUCAPS Sounding 1500 UTC 7 October 2015 taken near Location 3 in the Air Mass RGB (Fig. 2) in a region representative of upper-level moist air (orange coloring) and mid-level clouds (green color)

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