Cloud, Aerosol, and Complex Terrain Interactions (CACTI) Field Campaign Report

Varble, Adam; Pnnl, Bnl; Nesbitt, S. W.; Salio, Paola; Ávila, Eldo E.; Borque, Paloma; DeMott, Paul J.; McFarquhar, Greg M.; Heever, Susan van den; Zipser, Edward J.; Gochis, David; Houze, Robert A.; Jensen, Michael P.; Kollias, P.; Kreidenweis, Sonia M.; Leung, Ruby; Rasmussen, Kristen L.; Romps, David M.; Williams, C. R.

doi:10.2172/1574024

Cited by 15 publications

(16 citation statements)

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“…The CACTI field campaign (Varble et al, 2019) took place in the Sierras de Córdoba mountain range of central Argentina from 15 October 2018 -30 April 2019. The campaign studied convective cloud life cycle and organization in a region of the world where orographic forcing along the Sierras de Córdoba mountain range enables repeated observations of deep convective initiation and upscale growth.…”

Section: Cacti: Sierras De Córdoba Arm Sitementioning

confidence: 99%

An Extended Radar Relative Calibration Adjustment (eRCA) Technique for Higher Frequency Radars and RHI Scans

Hunzinger

Hardin

Bharadwaj

et al. 2020

Preprint

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Abstract. This study extends the relative calibration adjustment technique for calibration of weather radars to higher frequency radars, as well as range-height indicator scans. The calibration of weather radars represents one of the most dominant sources of error for their use in a variety of fields including quantitative precipitation estimation and model comparisons. While most weather radars are routinely calibrated, the frequency of calibration is often less than required resulting in miscalibrated time periods. While full absolute calibration techniques often require the radar to be taken offline for a period of time, there have been online calibration techniques discussed in the literature. The relative calibration adjustment (RCA) technique uses the statistics of the ground clutter surrounding the radar as a monitoring source for the stability of calibration but has only been demonstrated to work at S- and C-Band for plan-position indicator scans at a constant elevation. In this work the RCA technique is modified to work with higher frequency radars, including Ka-band cloud radars. At higher frequencies the properties of clutter can be much more variable. This work introduces an extended clutter selection procedure that incorporates the temporal stability of clutter and helps to improve the operational stability of RCA for relatively higher frequency radars. The technique is also extended to utilize range-height scans from radars where the elevation is varied rather than the azimuth. These types of scans are often utilized with research radars to examine the vertical structure of clouds. The newly extended technique (eRCA) is applied to four DOE-ARM weather radars ranging in frequency from C- to Ka- band. Cross comparisons of three co-located radars with frequencies C, X, and Ka at the ARM CACTI site show the technique can determine changes in calibration. Using an X-band radar at the ARM Eastern North Atlantic site, we show how the technique can be modified to be more resilient to clutter fields that show an increased variability, in this case due to sea clutter. The results show that this technique is promising for a-posteriori data calibration and monitoring.

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Section: Cacti: Sierras De Córdoba Arm Sitementioning

confidence: 99%

An Extended Radar Relative Calibration Adjustment (eRCA) Technique for Higher Frequency Radars and RHI Scans

Hunzinger

Hardin

Bharadwaj

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

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“…Moreover, the DOE ARM Cloud, Aerosol, and Complex Terrain Interactions (CACTI) and Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations (RELAMPAGO) field campaigns conducted during the austral warm season of 2018-2019 collected disdrometer observations in west-central Argentina near the Sierras de Córdoba (SDC) [56,57]. This north-south-oriented mountain range east of the Andes in subtropical South America is known to frequently initiate deep convection [56][57][58][59][60][61]. In addition, measurements from the Integrated Precipitation and Hydrology Experiment (IPHEx), which was conducted in the Appalachian Mountains of North Carolina (USA), formed an extensive DSD database for midlatitude mountainous terrain [62].…”

Section: Introductionmentioning

confidence: 99%

Raindrop Size Spectrum in Deep Convective Regions of the Americas

et al. 2021

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This study compared drop size distribution (DSD) measurements on the surfaces, the corresponding properties, and the precipitation modes among three deep convective regions within the Americas. The measurement compilation corresponded to two sites in the midlatitudes: the U.S. Southern Great Plains and Córdoba Province in subtropical South America, as well as to one site in the tropics: Manacapuru in central Amazonia; these are all areas where intense rain-producing systems contribute to the majority of rainfall in the Americas’ largest river basins. This compilation included two types of disdrometers (Parsivel and 2D-Video Disdrometer) that were used at the midlatitude sites and one type of disdrometer (Parsivel) that was deployed at the tropical site. The distributions of physical parameters (such as rain rate R, mass-weighted mean diameter Dm, and normalized droplet concentration Nw) for the raindrop spectra without rainfall mode classification seemed similar, except for the much broader Nw distributions in Córdoba. The raindrop spectra were then classified into a light precipitation mode and a precipitation mode by using a cutoff at 0.5 mm h−1 based on previous studies that characterized the full drop size spectra. These segregated rain modes are potentially unique relative to previously studied terrain-influenced sites. In the light precipitation and precipitation modes, the dominant higher frequency observed in a broad distribution of Nw in both types of disdrometers and the identification of shallow light precipitation in vertically pointing cloud radar data represent unique characteristics of the Córdoba site relative to the others. As a result, the co-variability between the physical parameters of the DSD indicates that the precipitation observed in Córdoba may confound existing methods of determining the rain type by using the drop size distribution.

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“…Despite their importance, high spatio‐temporal radar, surface, and upper‐air observations are sparse in most regions, including SESA. However, the RELAMPAGO (Remote sensing of Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive Ground Observations; RELAMPAGO, 2016)‐CACTI (Clouds, Aerosols, and Complex Terrain Interactions; Varble et al, 2018) field campaigns provided such high spatio‐temporal observations over central Argentina during Austral summer 2019 (Lang et al, 2020). In particular, Geostationary Operational Environmental Satellite‐16 (GOES‐16) Mesoscale Domain Sector (MDS) were provided by the National Oceanic and Atmospheric Administration (NOAA) and positioned over central Argentina upon request from the principal investigators of RELAMPAGO‐CACTI.…”

Section: Introductionmentioning

confidence: 99%

Distinctive Signals in 1‐min Observations of Overshooting Tops and Lightning Activity in a Severe Supercell Thunderstorm

et al. 2020

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This work examines a severe weather event that took place over central Argentina on 11 December 2018. The evolution of the storm from its initiation, rapid organization into a supercell, and eventual decay was analyzed with high-temporal resolution observations. This work provides insight into the spatio-temporal co-evolution of storm kinematics (updraft area and lifespan), cloud-top cooling rates, and lightning production that led to severe weather. The analyzed storm presented two convective periods with associated severe weather. An overall decrease in cloud-top local minima IR brightness temperature (MinIR) and lightning jump (LJ) preceded both periods. LJs provided the highest lead time to the occurrence of severe weather, with the ground-based lightning networks providing the maximum warning time of around 30 min. Lightning flash counts from the Geostationary Lightning Mapper (GLM) were underestimated when compared to detections from ground-based lightning networks. Among the possible reasons for GLM's lower detection efficiency were an optically dense medium located above lightning sources and the occurrence of flashes smaller than GLM's footprint. The minimum MinIR provided the shorter warning time to severe weather occurrence. However, the secondary minima in MinIR that preceded the absolute minima improved this warning time by more than 10 min. Trends in MinIR for time scales shorter than 6 min revealed shorter cycles of fast cooling and warming, which provided information about the lifecycle of updrafts within the storm. The advantages of using observations with high-temporal resolution to analyze the evolution and intensity of convective storms are discussed. Plain Language Summary Severe thunderstorms can have distinctive signals in satellite observations. Cloud-top temperature minima are one of the most studied metrics as a severe weather indicator. The newest geostationary weather satellites (GOES-16/17) offer a unique opportunity to study storms through their rapid-scan mode and lightning detector. In this study, we analyzed high-temporal (1-min) observations of cloud-top temperature and lightning detected from space and the surface to study the evolution of a severe thunderstorm that took place over central Argentina on 11 December 2018. Overall, cloud-top temperature minimum and fast increases in lightning activity preceded the occurrence of severe weather. The signature present in lightning observations provided the highest severe weather lead time, with ground-based sensors providing the maximum warning time (~30 min). A cloud-top temperature absolute minimum provided the shortest warning time, whereas secondary minima, that preceded the absolute minima, improved the warning time by more than 10 min. This improvement in lead time can result in better societal preparedness for imminent hazardous weather where no ground-based lightning observations are available. Observations with high-temporal resolution also show cycles of fast cloud-top cooling and warming that can provide important insight o...

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Cloud, Aerosol, and Complex Terrain Interactions (CACTI) Field Campaign Report

Cited by 15 publications

References 0 publications

An Extended Radar Relative Calibration Adjustment (eRCA) Technique for Higher Frequency Radars and RHI Scans

An Extended Radar Relative Calibration Adjustment (eRCA) Technique for Higher Frequency Radars and RHI Scans

Raindrop Size Spectrum in Deep Convective Regions of the Americas

Distinctive Signals in 1‐min Observations of Overshooting Tops and Lightning Activity in a Severe Supercell Thunderstorm

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