Search 2010-07-01~ 2011-09-08 bright band in abstract 9/8’11 このやり方では’bright’と‘band’が個別に検索される@9/16’11
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Typical
Patterns of Microwave Signatures and Vertical Profiles of Precipitation in
the Midlatitudes from TRMM Data Munehisa K. Yamamoto, Kenji Nakamura Journal of Applied
Meteorology and Climatology Volume 50, Issue 6
(June 2011) pp. 1236-1254 doi: 10.1175/2010JAMC2539.1 [Abstract]
[Full
Text] [PDF (2961 KB)] [Add
to Favorites] Representative
patterns from multichannel microwave brightness temperature Tb in the midlatitude oceanic region, observed by the Tropical
Rainfall Measuring Mission (TRMM) Microwave Imager (TMI), are studied during
precipitation events detected by the TRMM precipitation radar (PR) for three
summer and winter seasons using empirical orthogonal function (EOF) analysis.
The first three patterns are interpreted as rain liquid water, solid
particles, and rain type based on the frequency distributions of vertical
profiles of the radar reflectivity factor and the heights of the storm top,
cloud top, and freezing level. The first EOF (EOF1) correlates with the
near-surface rain rate. While the eigenvector for the 85.5-GHz channel is
less significant for EOF1 variability in summer, those in all channels
contribute equally to the variability in winter. This difference suggests
that summer precipitation is caused by additional solid particles formed in
developing precipitation systems. The second EOF (EOF2) represents the number
of solid particles and also corresponds to the near-surface rain rate. This
result suggests an increase of solid particles with the development of
precipitation systems. EOF2 varies largely by echo-top height in summer and
by echo-top height and freezing height in winter. The positive component
score has double Tb peaks. Dividing the score into two patterns according to
these peaks reveals highly developed precipitation systems, such as
convective rainbands and frontal systems, and weak
precipitation with shallow systems caused by cold outbreaks in the winter
case. The negative component score also shows shallow and weak precipitation
systems with warm rain. The third EOF (EOF3) is related to rain type.
Vertical profiles show a significant bright band with a small height
difference between the echo top and freezing level for negative EOF3, while
positive EOF3 has no bright band with a high echo top relative to the
freezing height. The results indicate that stratiform
and convective precipitation systems can be characterized by EOF3 TRMM-PRをEOF解析した【TMIは何に使う？】。3つの顕著な成分が出現し１は、地上降水に対応する降水量、2は下層の降水に対応する個体粒子、3は雲のタイプの変動を表現した。タイプ3はエコートップ付近にブライトバンドがあるときは負、エコー頂が高いがBBがない場合は正のEOFをしめした。9/8’11 |
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Polarimetric
estimates of a one month accumulation of light rain with a 3-cm wavelength
radar L. Borowska, D. Zrnic, A. Ryzhkov, P. Zhang, C. Simmer Journal of
Hydrometeorology Volume 0, Issue 0 (
) pp. doi: 10.1175/2011JHM1339.1 [Abstract]
[PDF (812 KB)] [Add
to Favorites] Abstract We evaluate rainfall
estimates from the new polarimetric X-band radar at Bonn, Germany, for a period
between mid of November and end of December 2009 by comparison with rain
gauges. The emphasis is on slightly more than one month accumulations over
areas minimally affected by beam blockage. The rain regime was characterized
by reflectivities mainly below 45 dBZ, maximum observed rain rates of 47 mm h−1, mean rain
rate of 0.1 mm h−1 and bright band altitudes between 0.6 km and 2.4 km above
the ground. Both the reflectivity factor and the specific differential phase
are used to obtain the rain rates. The accuracy of rain total estimates is
evaluated from the statistics of the differences between radar and rain gauge
measurements. Polarimetry provides improvement in
the statistics of reflectivity based measurements by reducing the bias and
RMS errors from −25% to 7 % and 33% to 17 % respectively. Essential to this
improvement is separation of data into those attributed to pure rain, those
from the bright band, and those due to nonmeteorological
scatterers. A type specific (rain or wet snow)
relation is applied to obtain the rain rate by matching on the average the
contribution by wet snow to the radar measured rainfall below the bright
band. The measurement of rain using specific differential phase is the most
robust and can be applied to the very low rain rates and still produce
credible accumulation estimates characterized with a standard deviation of
11% but a bias of −25%. A composite estimator is also tested and discussed. Xバンド偏波レーダの降雨推定精度を評価した。ドイツ、ボン、2009年の11月中から12月。 1か月半の積算雨量を、遮蔽のない領域について精度良く求めることができた。降水量は大きくなくおおむね45dBZ、最大で47mm/h、平均の降水量は0.1mm/hである。ブライトバンドは0.6~2.4㎞である。Zとφdpを、降水強度を求めるのに使っている。偏波を使うことでバイアスが-25から7%、自乗平均誤差が33~17％へ改善した。ポイントは雨と湿った雪を分類したことである。Φdpを使った雨の予測はしっかりとした精度を与える。9/9’11 |
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Empirical
Correction of Stray Light within the MERIS Oxygen A-Band Channel Rasmus Lindstrot,
Rene Preusker, Jürgen Fischer Journal of
Atmospheric and Oceanic Technology Volume 27, Issue 7
(July 2010) pp. 1185-1194 doi: 10.1175/2010JTECHA1430.1 [Abstract]
[Full
Text] [PDF (2900 KB)] [Add
to Favorites] 衛星から酸素吸収帯を測定する話（見送り）。9/12’11 |
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A
Real-Time Algorithm for the Correction of Brightband
Effects in Radar-Derived QPE Jian Zhang, Youcun Qi Journal of
Hydrometeorology Volume 11, Issue 5
(October 2010) pp. 1157-1171 doi: 10.1175/2010JHM1201.1 [Abstract]
[Full
Text] [PDF (5448 KB)] [Add
to Favorites] A Real-Time Algorithm for the Correction of Brightband Effects in Radar-Derived QPE The bright band (BB)
is a layer of enhanced reflectivity due to melting of aggregated snow and ice
crystals. The locally high reflectivity causes significant overestimation in
radar precipitation estimates if an appropriate correction is not applied.
The main objective of the current study is to develop a method that
automatically corrects for large errors due to BB effects in a real-time
national radar quantitative precipitation estimation (QPE) product. An
approach that combines the mean apparent vertical profile of reflectivity
(VPR) computed from a volume scan of radar reflectivity observations and an
idealized linear VPR model was used for computational efficiency. The
methodology was tested for eight events from different regions and seasons in
the United States. The VPR correction was found to be effective and robust in
reducing overestimation errors in radar-derived QPE, and the corrected radar
precipitation fields showed physically continuous distributions. The
correction worked consistently well for radars in flat land regions because
of the relatively uniform spatial distributions of the BB in those areas. For
radars in mountainous regions, the performance of the correction is mixed
because of limited radar visibility in addition to large spatial variations
of the vertical precipitation structure due to underlying topography. レーダの降水量定量観測のために、ブライトバンドを自動判定し、補正するアルゴリズムを作成した。 アメリカの地方季節が異なる8つのイベントで検証した。計算時間を節約するために、ボリュームスキャンで観測したVPRと、理想化した計算で求めたモデルVPRを用いた。VPR補正はブライトバンドの降水量過大評価を効率的に補正し、雨量を物理的に連続にする。平地では、BBが平らなので補正がうまくいくが、山地部では、補正の結果がうまくいかないものが混じる【mixed?】。これはレーダの遮蔽と、地形の影響により降雨の鉛直構造がかなり変化するためである。 【ポイント；BBの自動判定。最後の1文；地形が鉛直分布に与える影響を示したこと？】9/12’11 |
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Automated Lightning Flash Detection in
Nighttime Visible Satellite Data Richard L. Bankert, Jeremy E.
Solbrig, Thomas F. Lee, Steven D. Miller Weather and Forecasting Volume 26, Issue 3 (June 2011) pp. 399-408 doi: 10.1175/WAF-D-10-05002.1 [Abstract]
[Full
Text] [PDF (2806 KB)] [Add
to Favorites] 衛星から可視画像を用いて、自動で雷の発生をとらえるアルゴリズムを作った（見送り）9/12’11 |
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Objectively Determining the Rotational
Center of Tropical Cyclones in Passive Microwave Satellite Imagery Anthony J. Wimmers,
Christopher S. Velden Journal of Applied Meteorology and Climatology Volume 49, Issue 9 (September 2010) pp. 2013-2034 doi: 10.1175/2010JAMC2490.1
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Observations of Winter-time US West Coast
Precipitating Systems with W-band Satellite Radar and Other Spaceborne Instruments Sergey Y. Matrosov Journal of Hydrometeorology The potential of CloudSat W-band radar for observing winter-time storms affecting
the West Coast of North America is evaluated. Storms having high hydrological impact often result from
landfalls of “atmospheric rivers” (ARs) which are the narrow elongated regions of water vapor transport from the
tropics. CloudSat measurements are used for
retrievals of rain rate, R, and cloud ice water path (IWP) along the
satellite ground track over ocean and land. These retrievals present
quasi-instantaneous vertical cross-sections of precipitating systems with
high-resolution information about hydrometeors. This information is valuable
in coastal areas with complex terrain where observations with existing
instrumentation, including ground-based radars, are limited. CloudSat reflectivity enhancements (i.e., bright band –
BB) present a way to estimate freezing
levels, indicating transitions between rainfall and snowfall. CloudSat estimates of these levels were validated using
data from radiosonde soundings and compared to
model and microwave sounder data. Comparisons of CloudSat
retrievals of rain rates with estimates from ground-based radars in the areas
where measurements from these radars were available indicated an agreement
within retrieval uncertainties, which were around 50%. The utility of CloudSat was illustrated for case studies of pronounced
AR events at landfall and over ocean. Initial analysis of CloudSat
crossings of ARs during the 2006–07 season were used for rainfall regime
prevalence assessment. It indicated that stratiform
rain, which often had BB features, warm rain and hybrid rain were observed
with about 26%, 24% and 50% frequency. Stratiform
regions generally had higher rain rates. Significant correlation (~0.72)
between mean values of IWP and rain rate was observed for startiform
rainfall. Volume 0, Issue 0 ( ) pp. doi: 10.1175/JHM-D-10-05025.1 [Abstract]
[PDF (2194 KB)] [Add
to Favorites] 衛星からのW帯レーダ観測により、雲の鉛直分布がわかる。アメリカ西海岸では「大気の川（AR）」と呼ばれる、熱帯から長く延びる水蒸気輸送がある。ARが地上に降りてくることによって、地上ではしばしば水文学的に大きな影響が起きる。CloudSatでは軌道に沿って、降水強度、積分氷水量が観測できる。これらの積分値はほぼ同時刻に雲・降水粒子の鉛直分布を与える。複雑地形の沿岸部では、レーダを含む地上観測網は限られている。CloudSatのブライトバンドは融解高度を評価でき、雪から雨への遷移層がわかる。遷移層高度の評価をゾンデなどで行った。約50%の確度でアルゴリズムの有効性が示された。9/13’11 |
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A Novel Approach for Selective
Reconstruction of Cloud-Contaminated Satellite Images Bipasha Paul Shukla, P.
K. Pal, P. C. Joshi Journal of Atmospheric and Oceanic Technology Volume 28, Issue 8 (August 2011) pp. 1028-1035 doi: 10.1175/2011JTECHA1529.1 [Abstract]
[Full
Text] [PDF (1133 KB)] [Add
to Favorites] 衛星画像から雲を切り出す（取り除く）技術。観測した雲の形態と晴天時の地形データを使う。9/14’11skip |
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Evolving Multisensor
Precipitation Estimation Methods: Their Impacts on Flow Prediction Using a
Distributed Hydrologic Model David Kitzmiller Journal of Hydrometeorology This study investigates evolving methodologies for
radar and merged gauge-radar Quantitative Precipitation Estimation (QPE) to
determine their influence on the flow predictions of a distributed hydrologic
model. These methods include the National Mosaic and Quantitative
Precipitation algorithm package (NMQ), under development at the National
Severe Storms Laboratory(NSSL), and the Multisensor
Precipitation Estimator (MPE) and High-Resolution Precipitation Estimator
(HPE) suites currently operational at National Weather Service (NWS) field
offices. The goal of the study is to determine which combination of algorithm
features offer the greatest benefit toward operational hydrologic
forecasting. These features include automated radar quality control,
automated Z-R selection and bright-band identification, bias correction,
multiple-radar data compositing, and gauge-radar merging, all of which differ
between NMQ and MPE/HPE. To examine the spatial and temporal characteristics
of the precipitation fields produced by each of the QPE methodologies,
high-resolution (4-km, hourly) gridded precipitation estimates were derived
by each algorithm suite for three major precipitation events between 2003 and
2006 over sub-catchments within the Tar-Pamlico River Basin of North
Carolina. The results indicate that the NMQ radar-only algorithm suite
consistently yielded closer agreement with reference rain gauge reports than
did the corresponding HPE radar-only estimates. Similarly, the NMQ radar-only
QPE input generally yielded hydrologic simulations that were closer to
observations at multiple stream gauging points. These findings indicate that
the combination of Z-R selection and freezing level identification algorithms
within NMQ, but not incorporated within MPE and HPE, would have an
appreciable positive impact on hydrologic simulations. There were relatively
small differences between NMQ and HPE gauge-radar estimates in terms of
accuracy and impacts on hydrologic simulations, most likely due to the large
influence of the input rain gauge information. Volume 0, Issue 0 ( ) pp. doi: 10.1175/JHM-D-10-05038.1 David Kitzmiller, Suzanne Van Cooten, Feng Ding, Kenneth Howard, Carrie Langston, Jian Zhang, Heather Moser, Yu Zhang, Jonathan J. Gourley, Dongsoo Kim, David Riley [Abstract]
[PDF (3202 KB)] [Add
to Favorites] いくつかのインプットに対して分布型流出モデルの予測精度を評価する。4㎞格子1時間間隔で計算。キャリブレーションと融解層の判定を加えたレーダ雨量を与えた場合には流量との対応がおおむね良かった。MPE（多重降水量評価手法）やNMQ（定量評価アルゴリズム）【ともに流量予測のために活用されるシステムと考えられる、詳細は未調査】を加えることの、流量予測への影響はあまり大きくなかった。これは地上雨量計の情報が、もっとも流量予測への影響が強いためである。9/14’11 |
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Retrieval of ice cloud optical thickness
and effective particle size using a fast infrared radiative
transfer model Chenxi Wang, Ping Yang, Bryan A. Baum, Steven Platnick, Andrew K. Heidinger, Yongxiang Hu, Robert E. Holz Journal of Applied Meteorology and Climatology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JAMC-D-11-067.1 [Abstract]
[PDF (2447 KB)] [Add
to Favorites] 台風の中心位置を衛星画像から推定する。輝度温度と台風のバンドイメージを活用。下層の鉛直シアが弱い場合は推定誤差は17㎞、鉛直シアが強い場合は31㎞。9/16’11 |
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Radiance Comparisons of MODIS and AIRS
Using Spatial Response Information M. M. Schreier, B. H. Kahn,
A. Eldering, D. A. Elliott, E. Fishbein,
F. W. Irion, T. S. Pagano Journal of Atmospheric and Oceanic Technology Volume 27, Issue 8 (August 2010) pp. 1331-1342 doi: 10.1175/2010JTECHA1424.1
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Monitoring of IR Clear-sky Radiances over
Oceans for SST (MICROS) Xingming Liang, Alexander Ignatov Journal of Atmospheric and Oceanic Technology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JTECH-D-10-05023.1
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'bright band' で全テキストを検索。[2010-09-01]以降。9/16’11
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Polarimetric
estimates of a one month accumulation of light rain with a 3-cm wavelength
radar L. Borowska, D. Zrnic, A. Ryzhkov, P. Zhang, C. Simmer Journal of
Hydrometeorology Volume 0, Issue 0 (
) pp. doi:
10.1175/2011JHM1339.1 上にあり。 |
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Jian Zhang, Youcun Qi Journal of Hydrometeorology Volume 11, Issue 5 (October 2010) pp. 1157-1171 doi: 10.1175/2010JHM1201.1
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Observations of Winter-time US West Coast
Precipitating Systems with W-band Satellite Radar and Other Spaceborne Instruments Sergey Y. Matrosov Journal of Hydrometeorology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JHM-D-10-05025.1 上にあり10/4’11 |
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Typical Patterns of Microwave Signatures
and Vertical Profiles of Precipitation in the Midlatitudes
from TRMM Data Munehisa K. Yamamoto, Kenji Nakamura Journal of Applied Meteorology and Climatology Volume 50, Issue 6 (June 2011) pp. 1236-1254 doi: 10.1175/2010JAMC2539.1 |
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A Ground Validation Network for the
Global Precipitation Measurement Mission Mathew R. Schwaller, K.
Robert Morris Journal of Atmospheric and Oceanic Technology Volume 28, Issue 3 (March 2011) pp. 301-319 doi: 10.1175/2010JTECHA1403.1 A prototype Validation Network (VN) is currently
operating as part of the Ground Validation System for NASA’s Global
Precipitation Measurement (GPM) mission. The VN supports precipitation
retrieval algorithm development in the GPM prelaunch era. Postlaunch,
the VN will be used to validate GPM spacecraft instrument measurements and
retrieved precipitation data products. GPM用に検証用データをTRMM-PRと地上レーダで作成した。 The period
of record for the VN prototype starts on 8 August 2006 and runs to the
present day. The VN database includes spacecraft data from the Tropical
Rainfall Measuring Mission (TRMM) precipitation radar (PR) and coincident
ground radar (GR) data from operational meteorological networks in the United
States, Australia, Korea, and the Kwajalein Atoll in the Marshall Islands.
Satellite and ground radar data products are collected whenever the PR
satellite track crosses within 200 km of a VN ground radar, and these data
are stored permanently in the VN database. VN products are generated from
coincident PR and GR observations when a significant rain event occurs. 検証用データは2006年8月以降、TRMMから200㎞の幅に含まれる地上レーダデータを用いている。 The VN
algorithm matches PR and GR radar data (including retrieved precipitation
data in the case of the PR) by calculating averages of PR reflectivity (both
raw and attenuation corrected) and rain rate, and GR reflectivity at the
geometric intersection of the PR rays with the individual GR elevation
sweeps. The algorithm thus averages the minimum PR and GR sample volumes needed
to “matchup” the spatially coincident PR and GR data types. The result of
this technique is a set of vertical profiles for a given rainfall event, with
coincident PR and GR samples matched at specified heights throughout the
profile. データの一致が少ないところでも地上レーダとPRを組み合わせて、鉛直分布を作成する。 VN data can
be used to validate satellite measurements and to track ground radar
calibration over time. A comparison of matched TRMM PR and GR radar
reflectivity factor data found a remarkably small difference between the PR
and GR radar reflectivity factor averaged over this period of record in stratiform and convective rain cases when samples were
taken from high in the atmosphere. A significant difference in PR and GR
reflectivity was found in convective cases, particularly in convective
samples from the lower part of the atmosphere. In this case, the mean
difference between PR and corrected GR reflectivity was −1.88 dBZ. The PR–GR bias was found to increase with the amount
of PR attenuation correction applied, with the PR–GR bias reaching −3.07 dBZ in cases where the attenuation correction applied is
>6 dBZ. Additional analysis indicated that the
version 6 TRMM PR retrieval algorithm underestimates rainfall in case of
convective rain in the lower part of the atmosphere by 30%–40%. 層状性と対流性では、対流性の時に地上とPRとの違いが大きくなる。平均ではPRと補正した地上レーダの差は-1.88sBZであった。PRの減衰補正量が大きくなると差が大きくなり、減衰が6dBZより大きいときは-3.07dBZとなる。TRMM-PRは大気の下層で30-40%過小評価する。【結局はPRと地上レーダの比較の話？】10/7’11 |
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Polarimetric Radar Observation of the
Melting Layer in a Convective Rainfall System during the Rainy Season over
the East China Sea Yukari Shusse, Nobuhiro Takahashi, Katsuhiro Nakagawa, Shinsuke Satoh, Toshio Iguchi Journal of Applied Meteorology and Climatology Volume 50, Issue 2 (February 2011) pp. 354-367 doi: 10.1175/2010JAMC2469.1
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Leading and Trailing Anvil Clouds of West
African Squall Lines Jasmine Cetrone, Robert A. Houze Jr. Journal of the Atmospheric Sciences Volume 68, Issue 5 (May 2011) pp. 1114-1123 doi: 10.1175/2011JAS3580.1 The anvil clouds of tropical squall-line systems over West Africa have been examined using cloud radar data and divided into those that appear ahead of the leading convective line and those on the trailing side of the system. The leading anvils are generally higher in altitude than the trailing anvil, likely because the hydrometeors in the leading anvil are directly connected to the convective updraft, while the trailing anvil generally extends out of the lower-topped stratiform precipitation region. When the anvils are subdivided into thick, medium, and thin portions, the thick leading anvil is seen to have systematically higher reflectivity than the thick trailing anvil, suggesting that the leading anvil contains numerous larger ice particles owing to its direct connection to the convective region. As the leading anvil ages and thins, it retains its top. The leading anvil appears to add hydrometeors at the highest altitudes, while the trailing anvil is able to moisten a deep layer of the atmosphere. [Abstract]
[Full
Text] [PDF (1498 KB)] [Add
to Favorites] 【現象を解説する論文は難しい。要旨では現象しかわからない。おそらくイントロでは、既往研究と本論文の関連（位置づけ）が述べられていると考える】 熱帯のスコールラインに先行するかなとこ雲、あるいはスコールラインからたなびく（追随する）かなとこ雲についてレーダで降水過程を調べた。先行する雲は追随する雲に比べて高度が高い。先行する雲の降水粒子は対流による上昇流と直接関連している。一方で追随する雲は低い層状性の降水量域に広がっている。かなとこ雲を厚い・中くらい・薄いに分類すると、薄い部分と厚い先行雲は厚い追随雲より反射強度が大きく、先行雲は上昇流の先端で大粒子の氷がたくさんあると考えられる。先行する雲が成熟し薄くなるが、雲頂は保持される。先行雲は最大高度で降水粒子を種まきしているように思われる。一方で、追随雲は深い層の大気を湿らすことができる。10/11’11 |
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Identification of Vertical Profiles of
Reflectivity for Correction of Volumetric Radar Data Using Rainfall
Classification Pierre-Emmanuel Kirstetter, Hervé Andrieu, Guy Delrieu, Brice Boudevillain Journal of Applied Meteorology and Climatology Volume 49, Issue 10 (October 2010) pp. 2167-2180 doi: 10.1175/2010JAMC2369.1 Nonuniform beam filling associated with the vertical variation of atmospheric reflectivity is an important source of error in the estimation of rainfall rates by radar. It is, however, possible to correct for this error if the vertical profile of reflectivity (VPR) is known. This paper presents a method for identifying VPRs from volumetric radar data. The method aims at improving an existing algorithm based on the analysis of ratios of radar measurements at multiple elevation angles. By adding a rainfall classification procedure defining more homogeneous precipitation patterns, the issue of VPR homogeneity is specifically addressed. The method is assessed using the dataset from a volume-scanning strategy for radar quantitative precipitation estimation designed in 2002 for the Bollène radar (France). The identified VPR is more representative of the rain field than are other estimated VPRs. It has also a positive impact on radar data processing for precipitation estimation: while scatter remains unchanged, an overall bias reduction at all time steps is noticed (up to 6% for all events) whereas performance varies with type of events considered (mesoscale convective systems, cold fronts, or shallow convection) according to the radar-observation conditions. This is attributed to the better processing of spatial variations of the vertical profile of reflectivity for the stratiform regions. However, adaptation of the VPR identification in the difficult radar measurement context in mountainous areas and to the rainfall classification procedure proved challenging because of data fluctuations. [Abstract]
[Full
Text] [PDF (2069 KB)] [Add
to Favorites] 【読み込みが薄いと、当たり前になってしまう】大気からの反射強度【反射体？】が鉛直方向に変動することでビーム充満率が変動することが、降水強度推定の誤差となりえる。そこでVPRを定めて補正することは定量観測精度を高めるのに重要である。本研究では、体積観測を実施しているレーダでVPRを定める方法を提案する。ここでは、他仰角観測の比を利用することで、既存のVPRを定めるプログラムを改善することを目的としている。対象は2002年に定量観測が設計されたフランスのボーレンレーダとしている。ここで同定したVPRは、他の手法によるVPRよりも降雨の代表制が高い。これは、降雨推定に良い影響を与えるが、変動部分は依然残る。一方VPRの同定の精度は降雨成因によって異なる。他のレーダに応用することも可能であるが、レーダの変動があるので、山地部では難しい。10/12’11 |
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Polarimetric Doppler Radar Observations
of Kelvin–Helmholtz Waves in a Winter Storm Jana Lesak Houser, Howard B.
Bluestein Journal of the Atmospheric Sciences Volume 68, Issue 8 (August 2011) pp. 1676-1702 doi: 10.1175/2011JAS3566.1 Kelvin–Helmholtz waves were observed by the Twin Lakes,
Oklahoma (KTLX), Weather Surveillance Radar-1988 Doppler (WSR-88D); the
Norman, Oklahoma (KOUN), polarimetric WSR-88D; and the polarimetric
Collaborative Adaptive Sensing of the Atmosphere (CASA) radars on 30 November
2006 during a winter storm in central Oklahoma. The life cycle and structure
of the waves are analyzed from the radar data, and the nearby atmospheric
conditions are examined. The initial perturbations associated with the waves
are first evident only in the radars’ radial velocity fields. As the waves
mature, perturbations become discernable in the reflectivity factor Z and
spectrum width (S.W.) fields of both radars, and in the differential
reflectivity Zdr and, to a lesser extent, the
cross-correlation coefficient ρhv fields of KOUN.
As the waves break and begin to dissipate, the perturbations subside. A dual-Doppler analysis is synthesized to examine the kinematic structure of the waves and to relate the polarimetric observations to the kinematics. It is determined that Z and Zdr are enhanced in regions of upward motion (wave crests), and ρhv is reduced in the same vicinity and near the base of the wave circulations. Vertical velocity perturbations transport horizontal momentum upward and downward, inducing horizontal wind perturbations that are approximately 90° out of phase and downstream from their corresponding vertical velocity perturbations. Perturbations in Z, Zdr, and ρhv are observed in the vicinity of wave crests while S.W. perturbations occur predominately in and just upstream from wave troughs. It is determined that perturbations in the polarimetric variables are a result of the waves modifying local precipitation microphysics. Perturbations in Z and Zdr are hypothesized to be the result of columnar ice crystal generation whereas those in ρhv likely result from the mixing of ice crystals of various shapes and sizes. Perturbations in S.W. are a result of turbulent motions likely associated with wave breaking and downward advection of a strong shear layer. [Abstract]
[Full
Text] [PDF (5504 KB)] [Add
to Favorites] ケルビンホルムヘルツ波【成層は安定なのだけれど、上と下で速度が違うので、不安定を生じて発生する波】の寿命と構造を偏波レーダで調べた。上昇流とZ・ZDRの大きなところは関連していた。波に関連する初期擾乱は動径方向の成分のみで、最初に【すぐに；first】わかる。KOUNについてはρhvも調べた【KTLXは位相観測に対応していない？】。 上昇流のあるところと波の底面ではρhvは小さかった。鉛直速度は水泳の運動量を上方・下方に輸送し、輸送には水平風の擾乱を含んでいる。水平風は、上昇流と位相が90°ずれていて、鉛直速度擾乱を風下に運ぶことと対応している【？】10/13’11 10/18’11 Z,ZDR,ρhvの擾乱は波頭の付近で観測される。スペクトル幅の擾乱は谷の中あるいは風上側すぐで観測される。偏波パラメータの擾乱は局所的な降水を調整するような波の結果であるとわかった(決着をつけたdetermin)。10/21’11 |
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Evolving Multisensor
Precipitation Estimation Methods: Their Impacts on Flow Prediction Using a
Distributed Hydrologic Model David Kitzmiller, Suzanne Van
Cooten, Feng Ding,
Kenneth Howard, Carrie Langston, Jian Zhang,
Heather Moser, Yu Zhang, Jonathan J. Gourley, Dongsoo Kim, David Riley Journal of Hydrometeorology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JHM-D-10-05038.1 10/14’11 |
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A Robust Dual-Frequency Radar Profiling
Algorithm Mircea Grecu, Lin Tian, William S. Olson, Simone Tanelli Journal of Applied Meteorology and Climatology Volume 50, Issue 7 (July 2011) pp. 1543-1557 [Abstract]
[Full
Text] [PDF (2837 KB)] [Add
to Favorites] GPM用Ka（35.6G）とKu(13.8G)の2波長による降水量推定アルゴリズムの構築。2波長で探査できる範囲は狭い。Kaがなくても精度よく推定できるようにしたい。アルゴリズムの基本は以下。 １．Hitschfeld-Bordanの減衰補正を実施することでKuだけで降雨分布作成する。２．Kaの反射強度・地上参照法の減衰量と一致するようにKuの降雨分布を最適化する。 手法はNASAのTC４(熱帯合成・雲・気候連結)のキャンペーンと比較した。結果として2波長による降雨推定は短波長よりかなり良いが、結果は粒径分布の形や鉛直分布など推定に左右される。9/21’11 |
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A Study on the Feasibility of
Dual-Wavelength Radar for Identification of Hydrometeor Phases Liang Liao, Robert Meneghini Journal of Applied Meteorology and Climatology Volume 50, Issue 2 (February 2011) pp. 449-456 doi: 10.1175/2010JAMC2499.1 [Abstract]
[Full
Text] [PDF (1934 KB)] [Add
to Favorites] An important
objective for the dual-wavelength K u-/K a-band precipitation radar (DPR)
that will be on board the Global Precipitation Measurement (GPM) core
satellite is to identify the phase state of hydrometeors along the range
direction... To assess this, radar signatures are simulated in snow and rain
to explore the relation between the differential frequency ratio (DFR),
defined as the difference of radar reflectivity factors between Ku and Ka bands, and the radar reflectivity factor at Ku band ZKu for different hydrometeor types. Model simulations
indicate that there is clear separation between snow and rain in the ZKu–DFR plane assuming that the snow follows the
Gunn–Marshall size distribution and rain follows the Marshall–Palmer size
distribution… In an effort to verify the simulated results, the data
collected by the Airborne Second-Generation Precipitation Radar (APR-2) in
the Wakasa Bay Advanced Microwave Scanning
Radiometer for Earth Observing System (AMSR-E) campaign are employed. . Using
the signatures of linear depolarization ratio at Ku band, the APR-2 data can
be easily divided into the regions of snow, mixed phase, and rain for stratiform storms. These results are then superimposed
onto the theoretical curves computed from the model in the ZKu–DFR plane. For over 90% of the observations from a
cold-season stratiform precipitation event, snow
and rain can be distinguished if the Ku-band radar reflectivity exceeds 18 dBZ (the minimum detectable level of the GPM DPR at Ku
band). This is also the case for snow and mixed-phase hydrometeors. Although
snow can be easily distinguished from rain and melting hydrometeors by using
Ku- and Ka-band radar, the rain and mixed-phase
particles are not always separable. It is concluded that Ku- and Ka-band dual-wavelength radar might provide a potential
means to identify the phase state of hydrometeors. 2波長レーダ（Ku/Ka）を使って雨雪判別。偏波比・ZKu平面で雪と雨が分類できる。雪と雨・霙は分類しやすいが、霙の分類は難しい。 第2世代の航空機搭載レーダを利用。9/22’11 |
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Simplified Active Array L-Band Radar for
Atmospheric Wind Profiling: Initial Results P. Srinivasulu, P. Yasodha, A. Jayaraman, S. N.
Reddy, S. Satyanarayana Journal of Atmospheric and Oceanic Technology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JTECH-D-11-00011.1 [Abstract]
[PDF (3417 KB)] [Add
to Favorites] A simple approach is
presented to implement active aperture radar with constrained beam-forming
network that is adequate enough to generate multiple beams for atmospheric
wind profiling… In this approach, elements of the antenna array are fed
directly by dedicated transceiver modules, which are realized with
commercially available communication components making them low cost. A
passive two-dimensional beam-forming network distributes the exciter output
signal and feeds the transceivers with appropriate phase distribution to
generate different beams. This configuration, which is a simplified active
array, eliminates the feed loss and achieves best signal-to-noise (SNR)
ratio, thereby range coverage. Consequently, this scheme allows smaller
antenna size when compared to a conventional passive array system, for the
given range performance, and makes the wind profiler compact and
transportable. A 1280 Mega Hz 64-element simplified active array radar has
been developed, successfully validated and being operated at Gadanki, a tropical station in the south India. Measured
winds are in good agreement with those obtained with a collocated GPS-Sonde technique. This paper presents the configuration
and sample results of the system… 合成開口レーダに、ビーム形成ネットワーク【？】上の制限を設ける。ただし、ビーム生成ネットワークは、大気レーダとして複数ビームを生成するには十分の大きさを持つ。この方法で、個々のアンテナがトランシーバに直結できる。商用の部品をつかえて、コストが小さく、持ち運びもできるようなる。9/22’11 |
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Cross Validation of Spaceborne
Radar and Ground Polarimetric Radar Aided by Polarimetric Echo Classification
of Hydrometeor Types Yixin Wen, Yang Hong, Guifu
Zhang, Terry J. Schuur, Jonathan J. Gourley, Zac Flamig, K. Robert Morris, Qing Cao Journal of Applied Meteorology and Climatology Volume 50, Issue 7 (July 2011) pp. 1389-1402 doi: 10.1175/2011JAMC2622.1 [Abstract]
[Full
Text] [PDF (2761 KB)] [Add
to Favorites] Ground-based
polarimetric weather radar is arguably【議論の余地は残っているものの】 the most powerful validation tool that provides
physical insight into the development and interpretation of spaceborne weather radar algorithms and observations.
This study aims to compare and resolve discrepancies in hydrometeor
retrievals and reflectivity observations between the NOAA/National Severe
Storm Laboratory “proof of concept” KOUN polarimetric Weather Surveillance
Radar-1988 Doppler (WSR-88D) and the spaceborne
precipitation radar (PR) on board NASA’s Tropical Rainfall Measuring Mission
(TRMM) platform. An intercomparison of PR and KOUN
melting-layer heights retrieved from 2 to 5 km MSL shows a high correlation
coefficient of 0.88 with relative bias of 5.9%. A resolution volume–matching
technique is used to compare simultaneous TRMM PR and KOUN reflectivity
observations. The comparisons reveal an overall bias of <0.2% between PR
and KOUN. The bias is hypothesized to be from non-Rayleigh scattering effects
and/or errors in attenuation correction procedures applied to Ku-band PR
measurements. By comparing reflectivity with respect to different hydrometeor
types (as determined by KOUN’s hydrometeor classification algorithm), it is
found that the bias is from echoes that are classified as rain–hail mixture,
wet snow, graupel, and heavy rain. These results
agree with expectations from backscattering calculations at Ku and S bands,
but with the notable exception of dry snow. Comparison of vertical
reflectivity profiles shows that PR suffers significant attenuation at lower
altitudes, especially in convective rain and in the melting layer. The
attenuation correction performs very well for both stratiform
and convective rain, however. In light of the imminent【差し迫った】 upgrade of the U.S. national weather radar network to
include polarimetric capabilities, the findings in this study will
potentially serve as the basis for nationwide validation of space-based
precipitation products and also invite synergistic development of coordinated
space–ground multisensor precipitation products. 地上のレーダKOUNデータを用いて、TRMM-PRデータからの降水粒子判別を検証した。融解層高度については地上にレーダによる判別と、PRからの判別で相関係数が0.88、バイアスが5.9%あった。総雨量の誤差は、非レイリーからの散乱と減衰補正のKuとSの違いによると考えられる。KOUNの降水判別アルゴリズムを用いて検証を行った。雹ありの降雨、湿った雪、霰、豪雨の判定はよく一致したが、乾いた雪の判定はかなりの例外があった。鉛直分布の比較では、PRが下層で減衰の影響を大きく受けていた。特に対流雲と融解層が顕著であった。ただし、減衰補正は層状性雲、対流性の雲ともによく行われた。USのレーダは更新されていくので宇宙からの観測雨量を検証し、さらには相乗効果でよい降水量を作成することができるようになる。9/26’11 |
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National Mosaic and Multi-sensor QPE
(NMQ) System – Description, Results and Future Plans Jian Zhang, Kenneth Howard, Carrie Langston,
Steve Vasiloff, Brian Kaney,
Ami Arthur, Suzanne Van Cooten, Kevin Kelleher,
David Kitzmiller, Feng
Ding, Dong-Jun Seo, Ernie Wells, Chuck Dempsey Bulletin of the American Meteorological Society Volume 0, Issue 0 ( ) pp. doi: 10.1175/BAMS-D-11-00047.1
[Abstract]
[PDF (2470 KB)] [Add
to Favorites] Capsule Summary The NMQ is a
research system that integrates radar, rain gauge, satellite, and numerical
weather prediction model data and generates fully automated, seamless
national 3-d radar mosaic and multi-sensor quantitative precipitation
estimations at very high spatial and temporal resolutions The National Mosaic
and Multi-sensor QPE (Quantitative Precipitation Estimation), or “NMQ”,
system was initially developed from a joint initiative between the National
Oceanic and Atmospheric Administration（NOAA）/National Severe Storms Laboratory, the Federal
Aviation Administration/Aviation Weather Research Program and the Salt River
Project. Further development has continued with additional support from the
National Weather Service (NWS) Office of Hydrologic Development, the NWS
Office of Climate, Water, and Weather Services, and the Central Weather
Bureau of Taiwan. The objectives of NMQ research and development (R&D)
are 1) to develop a hydrometeorological platform
for assimilating different observational networks towards creating high
spatial and temporal resolution multi-sensor QPEs for flood warnings and
water resource management and 2) to develop a seamless high-resolution
national 3-D grid of radar reflectivity for severe weather detection, data
assimilation, numerical weather prediction model verification, and aviation
product development. Through about ten years
of R&D, a real-time NMQ system has been implemented (http://nmq.ou.edu).
Since June 2006, the system has been generating high-resolution 3-D
reflectivity mosaic grids (31 vertical levels) and a suite of severe weather
and QPE products in real-time for the conterminous United States at a 1-km
horizontal resolution and 2.5 minute update cycle. The experimental products
are provided in real-time to end users ranging from government agencies,
universities, research institutes and the private sector and have been
utilized in various meteorological, aviation, and hydrological applications.
Further, a number of operational QPE products generated from different
sensors (radar, gauge, satellite) and by human experts are ingested in the
NMQ system and the experimental products are evaluated against the
operational products as well as independent gauge observations in real-time. The NMQ is a fully
automated system. It facilitates systematic evaluations and advances of hydrometeorological sciences and technologies in a
real-time environment, and serves as a test bed for rapid
science-to-operation infusions. This paper describes scientific components of
the NMQ system, and presents initial evaluation results and future
development plans of the system. NMQと呼ばれるレーダを活用した定量観測システムが起動している。研究レベル。水平格子は1㎞、時間更新2.5分。最初はNOAAで開発、その後はNWSの協力を得た。台湾の気象局も参加している。NMQの目的は1）洪水警報を早期に出すための複合観測による降雨の定量評価、と2）反射強度因子の継ぎ目のない3次元分布を示すこと、である。 NMQは科学から現業への急速な橋渡しの試験となる。本論文では、初期の結果と今後の計画を報告する。9/27’11 |
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Kinematics of the Secondary Eyewall Observed in Hurricane Rita (2005) Anthony C. Didlake Jr.,
Robert A. Houze Jr. Journal of the Atmospheric Sciences Volume 68, Issue 8 (August 2011) pp. 1620-1636 doi: 10.1175/2011JAS3715.1 [Abstract]
[Full
Text] [PDF (9010 KB)] [Add
to Favorites] Airborne Doppler
radar data collected from the concentric eyewalls
of Hurricane Rita (2005) provide detailed three-dimensional kinematic
observations of the secondary eyewall feature. The
secondary eyewall radar echo shows a ring of heavy
precipitation containing embedded convective cells【第2眼雲は豪雨のリング状を示し、豪雨域には、そこに埋め込まれた積乱雲を含んでいる－リングは台風の眼を中心とする大きな輪のことか？】, which have no
consistent orientation【方位方向】 or radial location【動径方向】. The axisymmetric mean structure has a tangential wind
maximum within the reflectivity maximum at 2-km altitude and an elevated
distribution of its strongest winds on the radially outer edge. The corresponding
vertical vorticity field contains a low-level
maximum on the inside edge, which is part of a tube of increased vorticity that rises through the center of the
reflectivity tower and into the midlevels. The
secondary circulation consists of boundary layer inflow that radially
overshoots the secondary eyewall. A portion of this
inflowing air experiences convergence and supergradient
forces that cause the air to rise and flow radially outward back into the
center of the reflectivity tower. This mean updraft stretches and tilts the vorticity field to increase vorticity
on the radially inner side of the tangential wind maximum. Radially outside
this region, perturbation motions decrease the vorticity
at a comparable rate. Thus, both mean and perturbation motions actively
strengthen the wind maximum of the secondary eyewall.
These features combine to give the secondary eyewall
a structure different from the primary eyewall as
it builds to become the new replacement eyewall 第2目雲の力学的構造。航空機搭載型のレーダで目雲を観測。リング状の降雨で形成される。最大エコー強度2㎞での風の場を調査。 【具体の構造は難しい】第2の眼の壁は入れ替わっているらしい。 未9/28’11 |
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Modeling, Error Analysis, and Evaluation of
Dual-Polarization Variables Obtained from Simultaneous Horizontal and
Vertical Polarization Transmit Radar. Part II: Experimental Data J. C. Hubbert, S. M. Ellis,
M. Dixon, G. Meymaris Journal of Atmospheric and Oceanic Technology Volume 27, Issue 10 (October 2010) pp. 1599-1607 doi: 10.1175/2010JTECHA1337.1 In this second article in a two-part work, the biases of weather radar polarimetric variables from simultaneous horizontally and vertically transmit (SHV) data are investigated. The biases are caused by cross coupling of the simultaneously transmitted vertical (V) and horizontal (H) electric fields. There are two primary causes of cross coupling: 1) the nonzero mean canting angle of the propagation medium (e.g., canted ice crystals) and 2) antenna polarization errors. Given herein are experimental data illustrating both bias sources. In Part I, a model is developed and used to quantify cross coupling and its impact on polarization measurements. Here, in Part II, experimental data from the National Center for Atmospheric Research’s (NCAR’s) S-band dual-polarimetric Doppler radar (S-Pol) and the National Severe Storms Laboratory’s polarimetric Weather Surveillance Radar-1988 Doppler (WSR-88D), KOUN, are used to illustrate biases in differential reflectivity (Zdr). The S-Pol data are unique: both SHV data and fast alternating H and V transmit (FHV) data are gathered in close time proximity, and thus the FHV data provide “truth” for the SHV data. Specifically, the SHV Zdr bias in rain caused by antenna polarization errors is clearly demonstrated by the data. This has not been shown previously in the literature. [Abstract]
[Full
Text] [PDF (3659 KB)] [Add
to Favorites] 二偏波の同時発射による誤差を定量評価した。誤差の原因は交差結合【cross coupling？同時にHの場とVの場があるので、H観測のエコー成分がVとして観測されること？互いに影響しあう効果？】である。主に2つの原因があって、1）観測媒体が傾いていること（傾いた氷粒子など）、2）アンテナの偏波化の誤差。第1部では、モデルで偏波観測の誤差を論じた。第2部では、NCARのS-polとWSRR88DのKOUNでZDRの精度評価を行う。S-polは同時発射（SHV）も高速切り替え（FHV）もできるので、FHVをSHVに対する真値と考える。特にSHVのアンテナ誤差は明確に検出できた。この様な誤差はこれまで報告がない。9/29’11 |
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Polarimetric Radar-Based Estimates of
Spatial Variability in Charactersitic Sizes of Rain Drops in Stratiform Rainfall Sergey Y. Matrosov Journal of Applied Meteorology and Climatology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JAMC-D-11-053.1 Polarimetric X-band radar measurements of differential reflectivity, ZDR, in stratiform rainfall were used for retrieving mean mass-weighted raindrop diameters, Dm, and estimating their spatial variability δDm at different scales. ZDR data were calibrated and corrected for differential attenuation【減衰の差分？偏波の減衰?後者で】. The results revealed greater variability in Dm for larger spatial scales. Mean values of δDm, were around 0.32–0.34, 0.28–0.30, and 0.24–0.26 mm at scales of 20, 10, and 4.5 km, which are representative of footprints of various spaceborne sensors. For a given spatial scale, δDm, decreases when the mean value of Dm increases, which is a result of physical processes in rainfall and retrieval errors. At the 20 km scale the decreasing trend exhibits a factor of 1.7 decrease of δDm, when the average Dm changes from 1 to 2 mm. Estimation data suggest that this trend diminishes as the spatial scale decreases. Measurement noise and other uncertainties preclude accurate estimations of Dm variability at smaller spatial scales because for many data points estimated variability values are equal or less than the expected retrieval errors. Even though they are important for retrievals of absolute values of Dm, the details of the drop shape - size relation did not significantly affect estimates of size spatial variability. The polarization cross-coupling in simultaneous transmission-simultaneous receiving measurement mode presents another limiting factor for accurate estimations of Dm. This factor, however, was not too severe in estimations of the size variability. There are indications that tuning the differential attenuation correction scheme might balance off some possible cross-coupling ZDR bias if differential phase accumulation is less than 40°. [Abstract]
[PDF (3081 KB)] [Add
to Favorites] XバンドのZDRを用いてDm【質量中央粒径】を回帰的に求めて、異なるスケールでのDmの空間的な変動度、δDmを評価する。空間スケールが20，10、4.5㎞となるとδDmの平均値は0.32、0.28、0.24となった【スケールが小さくなると変動が小さい】。Dmが大きくなるとδDmは小さくなる、これは物理過程【大粒子ができるような場になると降水の形成過程としては安定する？】と回帰誤差の結果である。 小さい空間スケールは誤差が大きくなるが、Dmの変動にはそれほど敏感でない。偏波レーダでは同時発射式であることが新たな問題となりえるが、これは位相変化量が40°よりも小さい場合であれば、偏波を用いた減衰補正と起りそうなZDRのエラーがバランスする。10/5’11 |
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Value of a Dual-Polarized Gap-Filling
Radar in Support of Southern California Post-fire Debris-Flow Warnings David P. Jorgensen, Maiana N.
Hanshaw, Kevin M. Schmidt, Jayme L. Laber, Dennis M. Staley, Jason W. Kean, Pedro J. Restrepo Journal of Hydrometeorology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JHM-D-11-05.1 A portable truck-mounted C-band Doppler weather radar was deployed to observe rainfall over the “Station fire” burn area near Los Angeles, California, during the winter of 2009–2010 to assist with debris-flow【土石流】 warning decisions. The deployments were a component of a joint NOAA-USGS research effort to improve definition of the rainfall conditions that trigger debris flows from steep topography within recent wildfire burn areas. A procedure was implemented to blend various dual-polarized estimators of precipitation (for radar observations taken below the freezing level) using threshold values for differential reflectivity and specific differential phase shift that improves the accuracy of the rainfall estimates over a specific burn area sited with terrestrial tipping-bucket rain gauges. The portable radar outperformed local WSR-88D National Weather Service network radars in detecting rainfall capable of initiating post-fire runoff-generated debris flows. The network radars underestimated hourly precipitation totals by about 50%. Consistent with intensity-duration threshold curves determined from past debris-flow events in burned areas in southern California, the portable radar derived rainfall rates exceeded the empirical thresholds over a wider range of storm durations with a higher spatial resolution than local National Weather Service operational radars. Moreover, the truck-mounted C-band radar dual-pol-derived estimates of rainfall intensity provided a better guide to the expected severity of debris-flow events, based on criteria derived from previous events using rain gauge data, than traditional radar-derived rainfall approaches using reflectivity-rainfall relationships for either the portable or operational network WSR-88D radars. Part of the reason for the improvement was due to siting the radar closer to the burn zone than the WSR-88Ds, but use of the dual-polarimetric variables improved the rainfall estimation by ~12% over the use of traditional Z-R relationships. Abstract [Abstract]
[PDF (9139 KB)] [Add
to Favorites] 題：山火事後の土石流警報を支援する間を埋める【？】二重偏波レーダの価値 急斜面から山火事現場へ流入する土石流の発生をとらえるため、車搭載型のレーダを開発した。 レーダは有効で二重偏波を用いるとZR法より12%精度が向上した。10/14’11 |
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Wideband Waveform Design Principles for
Solid-state Weather Radars Nitin Bharadwaj, V. Chandrasekar Journal of Atmospheric and Oceanic Technology Volume 0, Issue 0 ( ) pp. doi: 10.1175/JTECH-D-11-00030.1 The use of solid-state【固体素子；東芝レーダの固体素子と同種かは未確認】 transmitters is becoming increasingly viable for atmospheric radars and is a key part of the strategy to realize any dense network of low powered radars. However, solid-state transmitters have low peak powers and this necessitates the use of pulse compression waveforms. In this paper frequency diversity wideband waveform design is proposed to mitigate low sensitivity of solid-state transmitters. In addition, the waveforms mitigate the range eclipsing problem associated with long pulse compression. An analysis of the performance of pulse compression using mismatched compression filters designed to minimize side lobe levels is presented. The impact of range side lobe level on the retrieval of Doppler moments are presented. Realistic simulations are performed based on CSU-CHILL radar data and Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) radar data. [Abstract]
[PDF (3028 KB)] [Add
to Favorites] 固体素子レーダでは低出力なのでネットワークを組むのに有効である。しかし、出力が弱いので波形【waveform？】のパルス圧縮が必要である。本論文では周波数が多彩な広い周波数帯を持つ波形を提案し、固体素子の発信機が持つ感度が低い、という欠点を補う。さらにレンジ方向の減衰【eclipse遮蔽？】問題を長いパルス圧縮と関連させることで軽減する。サイドローブを軽減するために、不一致の圧縮フィルタ【圧縮するときと解凍するときの周波数を変える？】を使った効果を解析する。解析されたドップラ速度成分に対するサイドローブレベルの効果を示す。実際のシミュレーションをCSUのCHILLレーダ、CASAのIP１レーダで実施した。10/16’11 |