SEARCH · Engineering Papers

Results for “Rh”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43

All sources NASA NTRS DOE OSTI

DOE OSTI2020

Materials Data on Ho7Rh3 by Materials Project

Ho7Rh3 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. there are three inequivalent Ho sites. In the first Ho site, Ho is bonded in a 3-coordinate geometry to three equivalent Rh atoms. All Ho–Rh bond lengths are 2.80 Å. In the second Ho site, Ho is bonded in a distorted L-shaped geometry to two equivalent Rh atoms. Both Ho–Rh bond lengths are 2.82 Å. In the third Ho site, Ho is bonded in a 3-coordinate geometry to three equivalent Rh atoms. All Ho–Rh bond lengths are 2.87 Å. Rh is bonded in a 6-coordinate geometry to six Ho atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Nd3Rh2 by Materials Project

Nd3Rh2 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are three inequivalent Nd sites. In the first Nd site, Nd is bonded in an octahedral geometry to six equivalent Rh atoms. All Nd–Rh bond lengths are 3.06 Å. In the second Nd site, Nd is bonded in a 6-coordinate geometry to six equivalent Rh atoms. There are three shorter (2.92 Å) and three longer (3.15 Å) Nd–Rh bond lengths. In the third Nd site, Nd is bonded in a 5-coordinate geometry to five equivalent Rh atoms. There are a spread of Nd–Rh bond distances ranging from 2.91–3.31 Å. Rh is bonded in a 8-coordinate geometry to eight Nd atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ho4MgRh by Materials Project

MgHo4Rh crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to three equivalent Mg and nine Ho atoms to form a mixture of corner and face-sharing MgHo9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.07 Å. There are a spread of Mg–Ho bond distances ranging from 3.30–3.54 Å. There are three inequivalent Ho sites. In the first Ho site, Ho is bonded in a bent 150 degrees geometry to two equivalent Mg, four equivalent Ho, and two equivalent Rh atoms. All Ho–Ho bond lengths are 3.63 Å. Both Ho–Rh bond lengths are 2.81 Å. In the second Ho site, Ho is bonded in a 4-coordinate geometry to two equivalent Mg, ten Ho, and two equivalent Rh atoms. There are two shorter (3.52 Å) and four longer (3.58 Å) Ho–Ho bond lengths. Both Ho–Rh bond lengths are 3.51 Å. In the third Ho site, Ho is bonded in a 3-coordinate geometry to three equivalent Mg, three equivalent Ho, and three equivalent Rh atoms. All Ho–Rh bond lengths are 2.81 Å. Rh is bonded in a 6-coordinate geometry to nine Ho atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Er4MgRh by Materials Project

MgEr4Rh crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to three equivalent Mg and nine Er atoms to form a mixture of corner and face-sharing MgEr9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.06 Å. There are a spread of Mg–Er bond distances ranging from 3.30–3.53 Å. There are three inequivalent Er sites. In the first Er site, Er is bonded in a 3-coordinate geometry to three equivalent Mg, three equivalent Er, and three equivalent Rh atoms. All Er–Er bond lengths are 3.51 Å. All Er–Rh bond lengths are 2.80 Å. In the second Er site, Er is bonded in a bent 150 degrees geometry to two equivalent Mg, four equivalent Er, and two equivalent Rh atoms. All Er–Er bond lengths are 3.62 Å. Both Er–Rh bond lengths are 2.80 Å. In the third Er site, Er is bonded in a 4-coordinate geometry to two equivalent Mg, ten Er, and two equivalent Rh atoms. All Er–Er bond lengths are 3.58 Å. Both Er–Rh bond lengths are 3.50 Å. Rh is bonded in a 6-coordinate geometry to nine Er atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Tm4MgRh by Materials Project

MgTm4Rh crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to three equivalent Mg and nine Tm atoms to form a mixture of face and corner-sharing MgTm9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.06 Å. There are a spread of Mg–Tm bond distances ranging from 3.27–3.51 Å. There are three inequivalent Tm sites. In the first Tm site, Tm is bonded in a 3-coordinate geometry to three equivalent Mg, three equivalent Tm, and three equivalent Rh atoms. All Tm–Tm bond lengths are 3.48 Å. All Tm–Rh bond lengths are 2.79 Å. In the second Tm site, Tm is bonded in a bent 150 degrees geometry to two equivalent Mg, four equivalent Tm, and two equivalent Rh atoms. All Tm–Tm bond lengths are 3.60 Å. Both Tm–Rh bond lengths are 2.79 Å. In the third Tm site, Tm is bonded in a 4-coordinate geometry to two equivalent Mg, ten Tm, and two equivalent Rh atoms. All Tm–Tm bond lengths are 3.57 Å. Both Tm–Rh bond lengths are 3.48 Å. Rh is bonded in a 6-coordinate geometry to nine Tm atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Sm4Rh6Pb19 by Materials Project

Sm4Rh6Pb19 crystallizes in the cubic I23 space group. The structure is three-dimensional. Sm is bonded in a 10-coordinate geometry to ten Pb atoms. There are a spread of Sm–Pb bond distances ranging from 3.29–3.56 Å. Rh is bonded in a 7-coordinate geometry to one Rh and six Pb atoms. The Rh–Rh bond length is 2.86 Å. There are a spread of Rh–Pb bond distances ranging from 2.73–2.94 Å. There are three inequivalent Pb sites. In the first Pb site, Pb is bonded in a 4-coordinate geometry to two equivalent Sm and two equivalent Rh atoms. In the second Pb site, Pb is bonded in a tetrahedral geometry to four equivalent Sm atoms. In the third Pb site, Pb is bonded in a 4-coordinate geometry to two equivalent Sm and two equivalent Rh atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Na3Rh by Materials Project

Na3Rh crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are three inequivalent Na sites. In the first Na site, Na is bonded in a distorted bent 120 degrees geometry to two equivalent Rh atoms. There are one shorter (2.92 Å) and one longer (3.01 Å) Na–Rh bond lengths. In the second Na site, Na is bonded in a distorted trigonal planar geometry to three equivalent Rh atoms. There are one shorter (2.94 Å) and two longer (2.98 Å) Na–Rh bond lengths. In the third Na site, Na is bonded in a distorted trigonal planar geometry to three equivalent Rh atoms. There are one shorter (3.02 Å) and two longer (3.03 Å) Na–Rh bond lengths. Rh is bonded in a 8-coordinate geometry to eight Na atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on YSiBRh3 by Materials Project

YRh3BSi crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Y is bonded in a 12-coordinate geometry to twelve equivalent Rh, three equivalent B, and three equivalent Si atoms. All Y–Rh bond lengths are 3.24 Å. All Y–B bond lengths are 3.18 Å. All Y–Si bond lengths are 3.18 Å. Rh is bonded in a distorted rectangular see-saw-like geometry to four equivalent Y, two equivalent B, and two equivalent Si atoms. Both Rh–B bond lengths are 2.30 Å. Both Rh–Si bond lengths are 2.38 Å. B is bonded in a 9-coordinate geometry to three equivalent Y and six equivalent Rh atoms. Si is bonded in a 6-coordinate geometry to three equivalent Y and six equivalent Rh atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Zr3Rh by Materials Project

Zr3Rh crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. there are three inequivalent Zr sites. In the first Zr site, Zr is bonded in a distorted water-like geometry to two equivalent Rh atoms. Both Zr–Rh bond lengths are 2.81 Å. In the second Zr site, Zr is bonded in a water-like geometry to two equivalent Rh atoms. There are one shorter (2.79 Å) and one longer (2.80 Å) Zr–Rh bond lengths. In the third Zr site, Zr is bonded in a 4-coordinate geometry to four equivalent Rh atoms. There are a spread of Zr–Rh bond distances ranging from 2.72–2.96 Å. Rh is bonded in a 8-coordinate geometry to eight Zr atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on LiRh3 by Materials Project

LiRh3 is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Li is bonded to twelve Rh atoms to form a mixture of corner, edge, and face-sharing LiRh12 cuboctahedra. There are four shorter (2.67 Å) and eight longer (2.69 Å) Li–Rh bond lengths. There are two inequivalent Rh sites. In the first Rh site, Rh is bonded to four equivalent Li atoms to form a mixture of distorted corner and edge-sharing RhLi4 cuboctahedra. In the second Rh site, Rh is bonded in a distorted square co-planar geometry to four equivalent Li atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Nd4MgRh by Materials Project

MgNd4Rh crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to three equivalent Mg and nine Nd atoms to form a mixture of corner and face-sharing MgNd9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.18 Å. There are a spread of Mg–Nd bond distances ranging from 3.42–3.66 Å. There are three inequivalent Nd sites. In the first Nd site, Nd is bonded in a 3-coordinate geometry to three equivalent Mg and three equivalent Rh atoms. All Nd–Rh bond lengths are 2.91 Å. In the second Nd site, Nd is bonded in a bent 150 degrees geometry to two equivalent Mg and two equivalent Rh atoms. Both Nd–Rh bond lengths are 2.91 Å. In the third Nd site, Nd is bonded in a 4-coordinate geometry to two equivalent Mg and two equivalent Rh atoms. Both Nd–Rh bond lengths are 3.62 Å. Rh is bonded in a 6-coordinate geometry to nine Nd atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on La4MgRh by Materials Project

MgLa4Rh crystallizes in the cubic F-43m space group. The structure is three-dimensional. Mg is bonded to three equivalent Mg and nine La atoms to form a mixture of face and corner-sharing MgLa9Mg3 cuboctahedra. All Mg–Mg bond lengths are 3.26 Å. There are a spread of Mg–La bond distances ranging from 3.49–3.73 Å. There are three inequivalent La sites. In the first La site, La is bonded in a 3-coordinate geometry to three equivalent Mg and three equivalent Rh atoms. All La–Rh bond lengths are 2.96 Å. In the second La site, La is bonded in a bent 150 degrees geometry to two equivalent Mg and two equivalent Rh atoms. Both La–Rh bond lengths are 2.98 Å. In the third La site, La is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mg and two equivalent Rh atoms. Both La–Rh bond lengths are 3.68 Å. Rh is bonded in a 6-coordinate geometry to nine La atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Na2RhS2O11 by Materials Project

Na2RhS2O11 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Na–O bond distances ranging from 2.31–2.78 Å. In the second Na site, Na is bonded to five O atoms to form distorted NaO5 trigonal bipyramids that share a cornercorner with one RhO5 square pyramid and corners with three SO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.32–2.82 Å. Rh is bonded to five O atoms to form RhO5 square pyramids that share corners with four SO4 tetrahedra and a cornercorner with one NaO5 trigonal bipyramid. There are a spread of Rh–O bond distances ranging from 1.86–2.08 Å. There are two inequivalent S sites. In the first S site, S is bonded to four O atoms to form SO4 tetrahedra that share corners with two equivalent RhO5 square pyramids and a cornercorner with one NaO5 trigonal bipyramid. There are a spread of S–O bond distances ranging from 1.45–1.55 Å. In the second S site, S is bonded to four O atoms to form SO4 tetrahedra that share corners with two equivalent RhO5 square pyramids and corners with two equivalent NaO5 trigonal bipyramids. There are a spread of S–O bond distances ranging from 1.45–1.55 Å. There are eleven inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to one Rh and one S atom. In the second O site, O is bonded in a distorted trigonal planar geometry to one Na, one Rh, and one S atom. In the third O site, O is bonded in a 3-coordinate geometry to two Na and one S atom. In the fourth O site, O is bonded in a bent 120 degrees geometry to one Na and one S atom. In the fifth O site, O is bonded in a 3-coordinate geometry to two Na and one S atom. In the sixth O site, O is bonded in a bent 120 degrees geometry to one Rh and one S atom. In the seventh O site, O is bonded in a bent 120 degrees geometry to one Na and one Rh atom. In the eighth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Rh, and one S atom. In the ninth O site, O is bonded in a bent 120 degrees geometry to one Na and one O atom. The O–O bond length is 1.23 Å. In the tenth O site, O is bonded in a distorted bent 150 degrees geometry to one Na and one S atom. In the eleventh O site, O is bonded in a trigonal non-coplanar geometry to two Na and one O atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Single-atom Rh/N-doped carbon electrocatalyst for formic acid oxidation

To meet the requirements of potential applications, it is of great importance to explore new catalysts for formic acid oxidation that have both ultra-high mass activity and CO resistance. In this work, we successfully synthesize atomically dispersed Rh on N-doped carbon (SA-Rh/CN) and discover that SA-Rh/CN exhibits promising electrocatalytic properties for formic acid oxidation. The mass activity shows 28- and 67-fold enhancements compared with state-of-the-art Pd/C and Pt/C, respectively, despite the low activity of Rh/C. Interestingly, SA-Rh/CN exhibits greatly enhanced tolerance to CO poisoning, and Rh atoms in SA-Rh/CN resist sintering after long-term testing, resulting in excellent catalytic stability. Density functional theory calculations suggest that the formate route is more favourable on SA-Rh/CN. According to calculations, the high barrier to produce CO, together with the relatively unfavourable binding with CO, contribute to its CO tolerance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Hydrolysis of methylphosphonic anhydride solid to methylphosphonic acid probed by Raman and infrared reflectance spectroscopies

Much is still unknown about the mechanisms and rates of environmental degradation of organophosphorous pesticides and agents. In this study we focus on the degradation of one organophosphorous compound, namely solid methyl phosphonic acid anhydride [CH3P(O)OHOP(O)OHCH3, MPAN] and its rate of conversion to methyl phosphonic acid (MPA) via heterogeneous hydrolysis. Pure MPAN was synthesized and loaded in open sample cups placed inside exposure chambers containing saturated salt solutions to control the relative humidity (RH). The reaction was monitored in the sample cup at various times using both infrared hemispherical reflectance (HRF) spectroscopy and Raman spectroscopy. Calibrated HRF and Raman spectra of both pure reagents as well as gravimetrically prepared mixtures were used to quantify the concentrations of MPAN and MPA throughout the reaction. Results show that both HRF and Raman spectroscopies are convenient non-invasive methods for detection of solid chemicals. The MPAN degradation rate displayed a very strong dependence on relative humidity: At room temperature the reaction showed 50% conversion of the MPAN in 761 ± 54 hours at 33% RH, 33 ± 4 hours at 43% RH, 17 ± 2 hours at 54% RH and just 7 ± 1 hours at 75% RH. Although MPAN hydrolysis is a second-order reaction, the 33 and 43% RH data, at early reaction times, could be fit with a zeroth order reaction, indicating water vapor and MPAN concentrations were not initially rate controlling. The 54 and 75% RH experiments showed significant deliquescence and decay data could only be fit assuming multiple reactions, implying chemical and/or physical processes partially controlled the hydrolysis rate, in contrast to a single process at low relative humidity.

methyl phosphonic acid, methyl phosphonic anhydrid↗

DOE OSTI2024

Fuel Cell Membrane Electrode Assemblies with Ultra-Low Pt Nanofiber Electrodes (Final Report)

H 2 /air fuel cell membrane-electrode-assemblies (MEAs) were fabricated with electrospun particle/polymer nanofiber mat cathodes (0.1 mg Pt /cm 2 or 0.2 mg Pt /cm 2 Pt/C, PtCo/C or PtNi/C) and anodes (0.1 mg/cm 2 Pt/C), where the binder was a mixture of acid-form perfluorosulfonic acid ionomer (e.g., Nafion™) and poly(acrylic acid) (PAA) carrier polymer or sodium-form PFSA with a carrier polymer of either PAA or polyethylene oxide (PEO). For the latter two cases, the water-soluble carrier was removed from the fibers after electrospinning. MEAs with Pt/C anode/cathode catalyst loadings of 0.1 mg Pt /cm2 each, an 1100 EW PFSA binder (Nafion™ dispersion), and a Nafion 211 membrane produced high power at both high and low relative humidity (RH) conditions, e.g., a maximum power density of 919 mW/cm 2 at 100% RH and 832 mW/cm 2 at 40% RH for a test at 80 °C and 200 kPa abs . The high power at low RH was attributed to nm-size pores within the fibers that trap water via capillary condensation thus maintaining a high proton conductivity of the PFSA binder in the cathode and especially the anode while minimizing/eliminating ionic isolation of catalyst particles in low water content, poorly conductive binder. At the same time, micro-porosity between fibers in the cathode allows for fast removal of electrogenerated water, thus minimizing cathode flooding. Nanofiber MEAs with Pt alloy catalyst cathodes also performed well, where a fibrous PtCo/C catalyst cathode at a loading of 0.1 mg/cm 2 produced 20% more power than a conventional powder cathode MEA, e.g., a maximum power density of 1,045 mW/cm 2 vs. 869 mW/cm 2 at 80 °C, 100% RH, and 200 kPa abs , and a PtNi/C fiber cathode MEAs prepared with Na+-form Nafion + PEO generated a maximum power of 820 mW/cm 2 at 40% RH. Fiber electrode MEAs with a neat Nafion binder (prepared from Na+-form Nafion + PEO or PAA) where the cathode Pt loading was ~0.1 mg/cm 2 exhibited a 25% loss in maximum power at 30,000 metal dissolution cycles, as compared to a 12% loss when the cathode binder was H+-form Nafion + PAA. The performance of a fiber mat electrode MEA with Pt/C catalyst (0.2 mg/cm 2 cathode loading and 0.1 mg/cm 2 anode loading) was excellent. At 80 oC and 200 kPa abs , the maximum power density was 1104 mW/cm 2 . The maximum power was independent of feed gas humidity for 40 < RH < 100%. The power loss after a metal dissolution AST (30,000 voltage cycles) was only 13%.

08 HYDROGEN↗

DOE OSTI2021

Effects of spatial resolution on WRF v3.8.1 simulated meteorology over the central Himalaya

The sensitive ecosystem of the central Himalayan (CH) region, which is experiencing enhanced stress from anthropogenic forcing, requires adequate atmospheric observations and an improved representation of the Himalaya in the models. However, the accuracy of atmospheric models remains limited in this region due to highly complex mountainous topography. This article delineates the effects of spatial resolution on the modeled meteorology and dynamics over the CH by utilizing the Weather Research and Forecasting (WRF) model extensively evaluated against the Ganges Valley Aerosol Experiment (GVAX) observations during the summer monsoon. The WRF simulation is performed over a domain (d01) encompassing northern India at 15 km x 15 km resolution and two nests (d02 at 5 km x 5 km and d03 at 1 km x 1 km) centered over the CH, with boundary conditions from the respective parent domains. WRF simulations reveal higher variability in meteorology, e.g., relative humidity (RH = 70.3%-96.1%) and wind speed (WS = 1.1-4.2m s(-1)), compared to the ERA-Interim reanalysis (RH D 80.0%-85.0%, WS D 1.2-2.3m s(-1)) over northern India owing to the higher resolution. WRF-simulated temporal evolution of meteorological variables is found to agree with balloon-borne measurements, with stronger correlations aloft (r = 0.44-0.92) than those in the lower troposphere (r = 0.18-0.48). The model overestimates temperature (warm bias by 2.8 degrees C) and underestimates RH (dry bias by 6.4 %) at the surface in d01. Model results show a significant improvement in d03 (P = 827.6 hPa, T = 19.8 degrees C, RH = 92.3 %), closer to the GVAX observations (P = 801.4 hPa, T = 19.5 degrees C, RH = 94.7 %). Interpolating the output from the coarser domains (d01, d02) to the altitude of the station reduces the biases in pressure and temperature; however, it suppresses the diurnal variations, highlighting the importance of well-resolved terrain (d03). Temporal variations in near-surface P, T, and RH are also reproduced by WRF in d03 to an extent (r>0:5). A sensitivity simulation incorporating the feedback from the nested domain demonstrates the improvement in simulated P, T, and RH over the CH. Our study shows that the WRF model setup at finer spatial resolution can significantly reduce the biases in simulated meteorology, and such an improved representation of the CH can be adopted through domain feedback into regional-scale simulations. Interestingly, WRF simulates a dominant easterly wind component at 1 km x 1 km resolution (d03), which is missing in the coarse simulations; however, the frequency of southeasterlies remains underestimated. The model simulation implementing a highresolution (3 s) topography input (SRTM) improved the prediction of wind directions; nevertheless, further improvements are required to better reproduce the observed local-scale dynamics over the CH.

Singh, Jaydeep↗

DOE OSTI2021

Combined Mesonet and Tracker

Title: Combined Mesonet and Trackers (UNL Mobile Mesonets) Authors University of Nebraska PI: Adam Houston, UNL Professor (ahouston2@unl.edu) Mailing Address: 126 Bessey Hall P.O. Box 880340 Lincoln, NE 68588-0340 CoMeT Overview The University of Nebraska-Lincoln operates three Combined Mesonet and Tracker (CoMeTs). CoMeTs are Ford Explorers (model years 2015, 2017, and 2019) with forward-mounted suites of meteorological sensors and dual moonroofs, combining the capability of a mobile mesonet to collect near-surface observations with the capability of an unmanned aircraft systems (UAS) tracker vehicle, which enables an observer in the second row of seats to see the aircraft and maintain compliance with Federal Aviation Administration policies on UAS operation. The CoMeTs collect observations of slow temperature and humidity at ~2 m above ground level (AGL) using a Vaisala HMP155A, fast temperature at ~2 m AGL using a Campbell Scientific 109SS-L thermistor, pressure at ~2.5 m AGL using a Vaisala PTB210, wind speed and direction at ~3.25 m AGL using an R.M. Young 05103 propeller anemometer, and vehicle heading using a KVH Industries C-100 fluxgate compass (Barbieri et al. 2019). The HMP155A and 109SS-L thermistor are shielded and aspirated within a U-tube (Waugh and Frederickson 2010; Houston et al. 2016). This list of sensors is also included in the CoMeT data file metadata. Manufacturer specifications for these instruments are given in Table 1 of Hanft and Houston (2018). The reported measured quantities are summarized below.CoMeT-3 was funded through an equipment allocation included in the NSF TORUS award (AGS-1824649). Instrument Description The specific sensors included on each CoMeT are summarized in the table at the end of this section. In general each CoMeT collects observations of slow temperature and humidity at ~2 m above ground level (AGL) using a Vaisala HMP155, fast temperature at ~2 m AGL using a Campbell Scientific 109SS-L thermistor, pressure at ~2.5 m AGL using a Vaisala PTB210 barometer with a Gill pressure port, wind speed and direction at ~3.25 m AGL using an R.M. Young 05103 propeller anemometer, position using a Garmin 19x HVS receiver, and vehicle heading using a KVH Industries C-100 fluxgate compass. The HMP155 and 109SS are shielded and aspirated within a U-tube (Waugh and Frederickson 2010; Houston et al. 2016). Fast temperature and corrected RH measurements (using sensors housed within the U-tube) have a time constant of 10-12 s based on data collected across a temperature and RH shock during the CLOUD-MAP 2017 calibration/validation tests on June 26, 2017. Vehicle speed was < 10 kts for this test. CoMeT-1 CoMeT-2 CoMeT-3 Slow Temperature Slow RH Vaisala HMP155A-L20-PT Part #: 22280-7 Vaisala HMP155E Part #: E1AA11A0B1A1A0A Vaisala HMP155E Part #: E1AA11A0B1A1A0A Fast temperature Campbell Scientific 109SS-L20-PT Part #: 21448-3 Campbell Scientific 109SS-L12-PW Part #: 21448-109 Campbell Scientific 109SS-L12-PW Part #: 21448-150 Pressure Vaisala PTB-210 Part #: A1A1B Gill Pressure Port Part #: 61002 Vaisala PTB-210 Part #: A1A1B Gill Pressure Port Part #: 61002 Vaisala PTB-210 Part #: A1A1B Gill Pressure Port Part #: 61002 Wind RM Young 05103-L20-PT Part #: 18435-310 RM Young 05103-L20-PW Part #: 18435-244 RM Young 05103-L20-PW Part #: 18435-244 GPS Garmin GPS 19x HVS (NMEA 0183) Part #: 010-01010-00 Garmin GPS 19x HVS (NMEA 0183) Part #: 010-01010-00 Garmin GPS 19x HVS (NMEA 0183) Part #: 010-01010-00 Compass KVH C-100 Part #: 01-0177-15 KVH C-100 Part #: 01-0177-15 KVH C-100 Part #: 01-0177-15 Logger Campbell Scientific CR6-NA-XT-SW Part #: 28385-9 Campbell Scientific CR6-WIFI-XT-SW Part #: 28385-6 Campbell Scientific CR6-WIFI-XT-SW Part #: 28385-6 Data Collection and Real-Time Processing The reported measured quantities are summarized in the table below. Quantity Units Source Epoch time Seconds GPS Latitude and longitude Degrees GPS Altitude m GPS Pressure hPa PTB210 Temperature (fast) deg C 109SS-L Temperature (slow) deg C HMP155 RH (slow) % HMP155 Vehicle speed m/s GPS Vehicle heading deg C-100 and GPS In addition to the measured variables, several derived variables are calculated. Corrected/fast relative humidity (%) Relative humidity is adjusted to the fast temperature following Richardson et al. (1998) and Houston et al. (2016). Water vapor mixing ratio (g/kg) Dew point temperature (°C) Potential temperature (Kelvin) Virtual potential temperature (Kelvin) Equivalent potential temperature (Kelvin) Regular intercomparisons between all three CoMeTs were performed during TORUS 2019. Comparisons were also conducted between CoMeT-1 and CoMeT-2 during LAPSE-RATE (2018) on 14 July. In these intercomparisons, the vehicles were parked adjacent to each other aligned perpendicular to (and facing into) the wind. To minimize engine heating effects, intercomparisons were only conducted when the wind speed was >10 kts. Data Format Original data files for each deployment are saved as text files and then converted to NetCDF. NetCDF versions have units that are CF compliant and may not match the original units in the txt files. The naming convention for the NetCDF files is as follows: UNL.CoMeT3.{deployment date YYYYMMDD}.{start time of observation collection in UTC HHMM}.L2.{post-processing codes}.cdf example: UNL.CoMeT3.20190627.1931.L2.g1.f1.cdf Post-processing codes are included to track modifications to the raw data. These codes are closely connected to error flags associated with each record. Each letter corresponds to a particular instrument: g: GPS p: Barometer tf: Fast temperature ts: Slow temperature rh: Relative humidity f: Compass w: Wind monitor a: All instruments Each number corresponds to a particular post-processing action described more below. Measured and derived variables are included in the following table. Variable Heading Standard Name Units time Time seconds since 00:00:00, 01-01-1970 Alt Altitude meters lat Latitude degrees north lon Longitude degrees east fast_temp Air Temperature kelvin slow_temp Air Temperature kelvin pressure Air Pressure pascals logger_RH Relative Humidity percent calc_corr_RH Relative Humidity percent wind_speed Wind Speed meters per second wind_dir Wind From Direction degrees vehicle_dir Vehicle Direction degrees dewpoint Dew Point Temperature kelvin mixing_ratio Humidity Mixing Ratio g/g theta Air Potential Temperature kelvin theta_v Virtual Potential Temperature kelvin theta_e Equivalent Potential Temperature Kelvin error_flag The error_flag variable is a string that matches the post-processing codes listed above. All instruments will have an associated code, but will have a “0” if the datum is unchanged from the initial processed value. Error Codes The following table summarizes the error codes for data collected before 2020: Error Code Relevant CoMeT Description g1 1,2,3 Exact correction. GPS position and time reprocessed from raw data g2 1 As far as we can tell this is an exact correction to an error in the GPS time. During the correct time periods the time suddenly went backwards ~250s and stayed at this offset for 750s when it corrected itself. The offset was applied to the “time warp” period. p1 2 Approximate correction. Hole in the pressure tube connecting the pressure port to the barometer. Resulted in erroneously low air pressure measurements when the vehicle was in motion. Derived variables recalculated (dew point temperature [e depends on qv and p], water vapor mixing ratio, potential temperature, virtual potential temperature, equivalent potential temperature) a1 3 Exact correction. Missing data reprocessed from raw data a2 1 Bug fix to bias correction for ts1, ts2, and rh1: water vapor mixing ratio was off by a factor of 10 and virtual potential temperature was wrong because of this. f1 3 No correction, missing data. Fluxgate compass inoperable. Wind speed and direction calculated using GPS-derived vehicle heading instead. rh1 1 Approximate correction. Constant bias of +1.7% removed from relative humidity. Derived variables recalculated (corrected/fast relative humidity, dew point temperature, water vapor mixing ratio, virtual potential temperature, equivalent potential temperature) ts1 1 Approximate correction. Constant bias of +0.6 K removed from slow temperature. Derived variables recalculated (corrected/fast relative humidity, dew point temperature, water vapor mixing ratio, virtual potential temperature, equivalent potential temperature) ts2 1 Approximate correction. Constant bias of +1.0 K removed. Derived variables recalculated (corrected/fast relative humidity, dew point temperature, water vapor mixing ratio, virtual potential temperature, equivalent potential temperature) References Bolton, D., 1980: The Computation of Equivalent Potential Temperature. Mon. Wea. Rev., 108, 1046–1053, https://doi.org/10.1175/1520-0493(1980)108<1046:TCOEPT>2.0.CO;2. Hanft, W., and A. L. Houston, 2018: An Observational and Modeling Study of Mesoscale Air Masses with High Theta-E. Mon. Wea. Rev., 146, 2503–2524, https://doi.org/10.1175/MWR-D-17-0389.1.Wexler Houston, A. L., R. J. Laurence III, T. W. Nichols, S. Waugh, B. Argrow, and C. L. Ziegler, 2016: Intercomparison of unmanned aircraft-borne and mobile mesonet atmospheric sensors. Journal of Atmospheric and Oceanic Technology. 33, 1569-1582, doi: 10.1175/JTECH-D-15-0178.1. Lowe, P. R., 1977: An Approximating Polynomial for the Computation of Saturation Vapor Pressure. J. Applied Meteorology, 16, 100–103. Richardson, S. J., S. E. Frederickson, F. V. Brock, and J. A. Brotzge, 1998: Combination temperature and relative humidity probes: Avoiding large air temperature errors and associated relative humidity errors. Preprints, 10th Symp. On Meteorological Observations and Instrumentation, Phoenix, AZ, Amer. Meteor. Soc., 278–283. Waugh, S., and S. E. Frederickson, 2010: An improved aspirated temperature system for mobile meteorological observations, especially in severe weather. 25th Conf. on Severe Local Storms, Denver, CO, Amer. Meteor. Soc., P5.2. [Available online at https://ams.confex.com/ams/25SLS/techprogram/paper_176205.htm.]

54 ENVIRONMENTAL SCIENCES↗