Level 2 retrieved temperature and moisture profiles in clear and partly cloudy conditions can be obtained from the new Cross-track Infrared Microwave Sounding Suite (CrIMSS), which uses infrared measurements from the Cross-track Infrared Sounder (CrIS) and microwave measurements from the Advanced Technology Microwave Sounder (ATMS). These observations are available from the Suomi-NPP as operational legacy observations to those coming on the JPSS.
SPoRT has begun processing the 42-level temperature and 22-level moisture CrIMSS Environmental Data Record (EDR) data and qualitatively comparing these soundings to other hyperspectral sounders (AIRS and IASI), in situ observations (RAOBs), and regional models (North American Mesoscale (NAM) and Rapid Refresh (RAP)). All of these comparisons are available on SPoRT’s hyperspectral sounding comparison page (http://weather.msfc.nasa.gov/sport/hyperspectral_comparisons/).
As an example of these comparisons, the three images below were taken from that webpage for soundings at Vandenberg Air Force Base (VBG) in California all valid around 2100 UTC on 31 March 2013. Note that the CrIMSS and AIRS soundings both match very closely to the RAP temperature sounding with near-perfect agreement of tropopause height in the AIRS sounding and similar tropopause placement in the CrIMSS sounding. Both the AIRS and CrIMSS soundings highlight a low-level moist conditions and mid-level dry conditions. Satellite soundings in this form can be used by forecasters to gain additional confidence in their model guidance or obtain additional information in regions where there are not other upper air observations (such as over Northern Mexico and the Gulf of Mexico).
Temperature and dew point soundings at VBG at 2100 UTC on 31 March 2013.
Temperature and dew point soundings from CrIMSS at VBG at 2100 UTC on 31 March 2013.
Temperature and dew point soundings from AIRS at VBG at 2100 UTC on 31 March 2013. Thicker line indicates highest quality data.
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Posted in AIRS, tagged AIRS, ozone on March 18, 2013 |
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Author: Emily Berndt
The AIRS project released AIRS version 6 data late last week. Significant improvements in data quality were immediately noticed here at SPoRT after the first image utilizing version 6 data was processed.
The first graphic is a plot of AIRS ozone utilizing version 5 data. You can see the gray regions, which represent gaps in the data and poor quality data due to cloud contamination. The second graphic is a plot of AIRS ozone utilizing version 6 data. There are far less gaps in data and data quality issues.
AIRS Ozone 1100 UTC March 14th 2013 utilizing version 5 data
AIRS Ozone 1200 UTC March 15th 2013 utilizing version 6 data
The last two images show the AIRS ozone and GOES West infrared imagery from 1400 UTC this morning. Focus on the low pressure system just south of the Aleutian Islands and compare the two images. Despite the cloud cover associated with the low pressure system, the AIRS ozone was minimally contaminated by the clouds and a clearer picture of ozone was retrieved. The AIRS project plans to process the entire mission as version 6 data by the end of 2013. Therefore the data quality issues will be addressed for the entire mission back to 2002.
AIRS Ozone 1400 UTC March 18th 2013 utilizing version 6 data
GOES West Infrared Satellite Imagery 1400 UTC March 18th 2013
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Moisture plumes from the tropical Pacific can extend into the mid-latitudes, and the CIRA Layer Precipitable Water (LPW) product based on microwave (AMSU, MHS) and infrared (AIRS) sounding instruments from NASA and NOAA polar-orbiting satelliltes provides information on the amount of moisture in each layer. Traditional total precipitable water (TPW) data only give part of the picture and Water Vapor (WV) imagery only captures the upper tropospheric moisture. Note here how the GOES WV imagery from the NASA GHCC site agrees well with the values of 2-4 mm in the 500-300 mb layer between Hawaii and the west CONUS.
500-300 mb Layer Precipitable Water by CIRA, 13 March 2013, 2100Z
GOES Water Vapor imagery from NASA GHCC site, 13 March 2013, 2130Z
In the images below, the surface to 850 mb layer shows a wide plume of 0.5 to 0.75 inches of PW extending from Hawaii to Washington and Oregon. Moving upwards, the 850 to 700 mb layer continues to show a wide swath of moisture (~0.25 to 0.5 inches) in this same area, with a sharp gradient to the east. Lastly, the 700 to 500 mb layer shows a more narrow moisture swath, but still with values ranging from ~0.25 to 0.33 inches, and extending into the northwest CONUS. The observations of vertical distribution of moisture in data void regions can be compared to NWP models as well as applied to estimating the available moisture at low levels for potential precipitation and flooding events.
Surface to 850 mb Layer Precipitable Water by CIRA, 13 March 2013, 2100Z
850 to 700 mb Layer Precipitable Water by CIRA, 13 March 2013, 2100Z
700 to 500 mb Layer Precipitable Water by CIRA, 13 March 2013, 2100Z
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The Northeast is bearing down for a blizzard as two storm systems are expected to merge off the East Coast early Saturday morning. Currently, one low pressure center is near Lake Erie and the other one is off the Virginia coast (see surface map below). Once the two systems phase off the East Coast, the new system is expected to rapidly deepen to 970 mb. Blizzard conditions will result as 1-2 feet of snow falls and winds gust to as high as 70 mph.
HPC 1500 UTC Surface Analysis Feb. 8, 2013
From a satellite perspective, how can some of the new GOES-R imagery and AIRS profiles help identify significant features associated with this unique synoptic set up? Below is an RGB Air Mass image from 0634 UTC this morning. The image gives a clear view of the coastal storm. Notice the green colors to the south of the main cloud shield, indicated by a blue arrow. The green colors represent warm, moist tropical air that is being drawn into the storm. This air mass will provide abundant moisture to produce the robust snow fall amounts expected. A VIIRS/CRiS RGB Air Mass image from 0733 UTC this morning gives a broader view of the Eastern United States and shows the structure of both storms. The storm situated over the Great Lakes will usher cold air into the Northeast. There are also green colors to the north and northwest of the Great Lakes storm however they indicate cold, moist air.
NASA SPoRT Aqua MODIS RGB Air Mass Image 0634 UTC Feb. 8, 2013.
Yellow arrow points to ozone rich stratospheric air and Blue arrow points to warm, moist tropical air.
NASA SPoRT VIIRS/CRiS RGB Air Mass Image 0733 UTC Feb. 8, 2013.
Yellow arrow points to ozone rich stratospheric air
Stratospheric intrusions are commonly associated with rapidly developing cyclones and may be responsible for transporting higher momentum air to the surface to produce damaging winds at the surface. If we piece together information from the RGB Air Mass imagery, AIRS total column ozone, and a 300 mb map, can we find an explanation to why this system will be associated with strong wind gusts? The 1200 UTC 300 mb observations, pictured below, show a 125 kt jet streak north of Maine. The red/orange colors in the MODIS RGB Air Mass imagery indicate the presence of a jet streak and high potential vorticity air. The AIRS total column ozone, pictured below, indicates higher values of ozone in the same vicinity. The presence of high potential vorticity air and larger amounts of ozone signify higher momentum stratospheric air intruding into the troposphere. Some of this stratospheric air is being drawn into the Great Lakes storm, shown by the yellow arrows on the VIIRS/CRiS RGB Air Mass image. Unfortunately there was not an AIRS pass to the east of the storm system to further confirm ozone-rich stratospheric air. As the system continues to progress, more AIRS data and RGB Air Mass data will be investigated to watch how stratospheric air is drawn into the storm and how it relates to the production of surface wind gusts.
300 mb Heights (dm) and Isotachs (kts) 1200 UTC Feb. 8, 2013. Image from NCAR RAL Real Time Weather Data website
AIRS Total Column Ozone 0630-0636 UTC Feb. 8, 2013
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Through collaborations partially funded by the Alaska Space Grant Program, SPoRT has been closely working with Dr. Don Morton at the Arctic Region Supercomputing Center at the University of Alaska Fairbanks to bring retrieved profiles from the Atmospheric Infrared Sounder (AIRS) into an operational forecast model. Don works very closely with Alaska NWS WFOs by providing an operational version of the High Resolution Rapid Refresh configured for an Alaska domain (HRRRAK) to help improve short-term forecasts. SPoRT has provided near-real-time AIRS retrieved profiles and guidance on configuring and running the Gridpoint Statistical Interpolation (GSI) data assimilation system to most effectively bring the observations into the operational forecasting system. Testing of the impact of the AIRS profiles within the system will continue for a few weeks, after which forecasts including AIRS profiles will be provided each day to Alaska region WFOs. An example of the initial analysis differences for 850 hPa temperatures from last Friday can be seen below. SPoRT will continue to work with Dr. Morton to evaluate and validate the impact of AIRS on HRRRAK short-term forecasts.
Initial impacts from assimilated AIRS profiles provided in real-time for input into the HRRRAK for the 850 hPa temperature analysis on 30 March 2012.
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Starting Tuesday, February 28, and running through March 1, SPoRT will be hosting its 6th Science Advisory Committee (SAC) meeting at the NSSTC in Huntsville, AL.
One of the topics to be shared with the SAC is the SPoRT-WRF, a real-time, experimental high-resolution model that combines SPoRT research projects (Land Information System, SPoRT SST composite, MODIS Greenness Vegetation Fraction, and assimilation of hyperspectral profiles from AIRS and IASI) into a single cohesive model to address the WFO and SPC forecast challenge of convection in numerical weather prediction. Today’s 00Z initialization of the SPoRT-WRF shows clearing conditions over the Huntsville area and only isolated afternoon and evening showers over the Atlanta area (one location some SAC members may be flying through this afternoon/evening) with clearing after around noon local time.
1-km AGL Reflectivity from SPoRT-WRF Initialized at 00Z on 27 February 2012 (click image to animate loop)
SPoRT looks forward to a great meeting!
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The dearth of upper air observations over the Pacific Ocean can lead to model initializations that contain very little observational data and revert to the background field. While this may be adequate, improvements in the initial conditions can yield improved forecasts. One particular forecast challenge for WFOs in Alaska, the Pacific and the West Coast of the United States is obtaining a correct moisture analysis over the Pacific Ocean. Streams of moisture called atmospheric rivers can stream ashore the North American Coastline and produce intense rainfall due to orographic lifting and may not be well-represented in models and analyses.
Currently, some offices are using a total precipitable water (TPW) product from CIRA that SPoRT has helped transition to the operational community. This product blends various satellite and GPS observations of TPW into a blended product that can be used to track atmospheric rivers and other moisture features. However, this particular product is not available to be used in model initialization. An additional source of satellite atmospheric moisture observations comes from NASA’s AIRS hyperspectral sounder. AIRS is able to see temperature and moisture in clear and partly cloudy conditions and produce vertical profiles of temperature and moisture. SPoRT is currently blending a GDAS analysis with AIRS temperature and moisture observations over the Pacific using the Gridpoint Statistical Interpolation data assimilation system to produce a three-dimensional moisture analysis product.
An example of the SPoRT AIRS 3D Moisture Analysis Product is given below for an atmospheric river case on 14 October 2009 that impacted the Western United States.
CIRA TPW product valid at 2301Z 13 October 2009
GDAS analysis valid at 0000Z 14 October 2009
SPoRT AIRS 3D Moisture Analysis Product valid at 0000Z 14 October 2009
In the above example, the CIRA TPW (top image) is taken as the observed state of the atmosphere. The GDAS analysis (middle image) used to initialize the 00Z GFS shows the TPW pattern consistent with the atmospheric river; however, the atmospheric river is too wide and is slightly more intense than indicated in the CIRA TPW product. Additionally, the areas surrounding the atmospheric river are too moist compared to the CIRA product. Upon assimilation of the AIRS temperature and moisture profiles (bottom image), the width of the atmospheric river tightens and the surrounding areas are dried. The resulting 3D analysis compares more favorably to the CIRA TPW product.
Future iterations of this same product will assimilate profile data from the Infrared Atmospheric Sounding Interferometer (IASI) and Cross-track Infrared Sounder (CrIS) using lessons learned from AIRS to produce an analysis valid at multiple times during the day.
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SPoRT has been collaborating with Don Morton and Kayla Harrison at the University of Alaska-Fairbanks to bring AIRS profile data into the High-Resolution Rapid Refresh for Alaska (HRRRAK), which is being developed for operational use at Alaska Region National Weather Service Offices. In this research activity, SPoRT provided AIRS profile observations in PREPBUFR format for assimilation into the Gridpoint Statistical Interpolation (GSI) used to initialize the HRRRAK. The following figures show the impact of the AIRS profile data on the GSI analysis.
1000 hPa analysis increment of conventional observations assimilated into HRRRAK at 0000 UTC on 20 August 2011
1000 hPa analysis increment of conventional observations and AIRS profiles assimilated into HRRRAK at 0000 UTC on 20 August 2011
It is clear that the assimilation of both conventional observations and AIRS profiles has a larger impact on the analysis than assimilation of conventional observations alone at this time for this pressure level. More work will be done to determine the forecast impact when the HRRRAK is initialized with each of these analyses and the forecasts are compared to in situ observations of sensible weather parameters.
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NASA’s Atmospheric Infrared Sounder (AIRS) has the capability of producing near-radiosonde quality vertical soundings with a vertical resolution much greater than previous sounders. SPoRT has successfully assimilated temperature and moisture soundings retrieved from AIRS into the WRF 3DVAR analysis system (WRF-Var) and assessed using 37 case study days from winter 2007. The assimilated data produce a 3-dimensional analysis that is then used to initialize a WRF forecast on a regional, 12-km domain.
One particular case in which AIRS has excelled is a February 13, 2007 extreme rainfall case in Eastern Texas prompted by a cold front pushing eastward across the Great Plains. On February 12, clear skies over Eastern Texas and the Western Gulf of Mexico allowed for the observation and assimilation of many high-quality AIRS profiles at around 0900Z. The figure below shows the location of the AIRS profiles. The colored pixels indicate the pressure above which the highest quality AIRS profiles are assimilated (e.g. black pixels denote profiles that have quality data all the way to the surface). Note that there is a large swath of AIRS profile data located over the Western Gulf of Mexico.
The WRF model was initialized at 0000 UTC on February 12, data were assimilated at 0900 UTC, and these AIRS-enhanced initial conditions were used to finish the forecast out to 24 hours. The image below depicts three model metrics from the 24-hour forecast (valid at 0000 UTC on February 13): 6-hour cumulative precipitation (top row), 1000 hPa dew point temperature (middle row), and convective available potential energy (CAPE). The far right column is the verifying “ground truth” analysis. For 6-hour cumulative precipitation, the truth field is gridded Stage IV precipitation fields, which combine radar and rain gauge data. For the dew point and CAPE fields, the North American Mesoscale (NAM) model analysis valid at 0000 UTC on 2/13 is used. The left column represents the Control (no AIRS) forecast; the middle column the AIRS-enhanced forecast.
With the inclusion of AIRS temperature and moisture profiles (upper middle), the intensity and location of the 6-hour cumulative precipitation maximum in the line of storms crossing Eastern Texas is represented much better than in the Control (upper left) compared to the Stage IV precipitation data (upper right). This convective precipitation is improved with the inclusion of AIRS due to improved forecasts of CAPE and lower-level moisture, which lead to greater instability in the model in that region. These improvements are validated in the comparisons to the NAM analysis. The advance of the 18-20 degree Celsius lower level dew points off the coast of Texas is depicted better in the AIRS-enhanced model run (middle) compared to the Control (middle left). Similarly, the AIRS-enhanced CAPE (lower middle) shows some of the 1800 J/kg CAPE values approaching the Texas coast that appear in the NAM analysis of CAPE (lower right). The Control run (lower left) has no CAPE values in that region above 1400 J/kg.
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Posted in AIRS on December 21, 2009 |
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Temperature and moisture profiles derived in near real-time from the Atmospheric Infrared Sounder (AIRS) on NASA’s Aqua satellite can help forecasters evaluate forecast model performance and to diagnose changing weather conditions. The example below illustrates the use of AIRS profiles in this way for Birmingham, Alabama on December 1, 2009. The top panels present NAM forecasts of the temperature and moisture structure of the atmosphere in the vicinity of Birmingham at 0300, 0600, and 0900UTC. The profiles indicate a low level inversion with a moist adiabatic profile above it, with little forecasted change with time. The 0700UTC AIRS profile (lower left) for the same region indicates a much warmer lower troposphere with a deeper inversion layer and much drier air aloft. The AIRS profile is more consistient with the 1200UTC rawinsonde observation (lower right), even though it represents conditions a few hours earlier. Note that the AIRS profile (thick line) does not extend to the ground because of overcast conditons. SPoRT is working to provide forecasters access to real-time AIRS profile data via AWIPS.
NAM, AIRS, and radiosonde profiles for Birmingham on December 1, 2009.
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