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Stephen E. Hobbs
and
Wayne W. Wolf

Abstract

Radar has been used to study insect flight for over 20 years. Radar, especially airborne radar, is unrivaled in its ability to observe the spatial organization of insect migration. This paper reports methods of data collection and analysis used by current airborne entomological radar systems and, in particular, the method used to review the data collected and visualize any large-scale structures detected. Examples of data from recent U.S. Department of Agriculture field experiments are presented to illustrate the analysis techniques. The data review method allows further data collection and analysis to be focused on areas of particular interest and thus significantly enhances the utility of airborne entomological radar.

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W. Viezee
,
P. A. Davis
, and
D. E. Wolf

Abstract

This note focuses on a new method of analysis, suitable for use with data from satellite microwave spectrometers, that may benefit hydrometeorological analysis and prediction. The method being proposed involves application of spectral microwave and infrared data such as available from the Nimbus 6 SCAMS/HIRS and Nimbus 5 ESMR experiments, or similar data forthcoming from Nimbus G and TIROS-N, to examine the moisture budget of storm areas over oceans.

Exploratory computations obtained by testing the proposed technique on a limited sample of available data are presented. Capabilities and limitations are noted.

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Roy M. Edlich
,
Daniel E. Wolf
,
Christopher T. Carlson
, and
Joseph W. Maresca Jr.

Abstract

Seasat-A scatterometer system (SASS) measurements of wind speed and direction and GOES-2 satellite measurements of cloud motion directions were used to analyze the surface wind field over part of the northern Pacific Ocean for 17 July and 3 October 1978. Surface pressure fields were computed from the nondivergent SASS-derived wind velocity fields using the balance equation and were compared to the National Meteorological Center surface pressure fields. Agreement between the balanced pressure-height fields and National Meteorological Center pressure fields was good. The linear correlation coefficient between the two fields was 0.91 for 17 July, and 0.84 for 3 October 1978. These results indicate that the surface wind and pressure fields of the global oceans (excluding a narrow equatorial zone where the balance equation is invalid) can be determined with acceptable accuracy by using satellite measurements exclusively.

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John T. Abatzoglou
,
Renaud Barbero
,
Jacob W. Wolf
, and
Zachary A. Holden

Abstract

Drought indices are often used for monitoring interannual variability in macroscale hydrology. However, the diversity of drought indices raises several issues: 1) which indices perform best and where; 2) does the incorporation of potential evapotranspiration (PET) in indices strengthen relationships, and how sensitive is the choice of PET methods to such results; 3) what additional value is added by using higher-spatial-resolution gridded climate layers; and 4) how have observed relationships changed through time. Standardized precipitation index, standardized precipitation evapotranspiration index (SPEI), Palmer drought severity index, and water balance runoff (WBR) model output were correlated to water-year runoff for 21 unregulated drainage basins in the Pacific Northwest of the United States. SPEI and WBR with time scales encompassing the primary precipitation season maximized the explained variance in water-year runoff in most basins. Slightly stronger correlations were found using PET estimates from the Penman–Monteith method over the Thornthwaite method, particularly for time periods that incorporated the spring and summer months in basins that receive appreciable precipitation during the growing season. Indices computed using high-resolution climate surfaces explained over 10% more variability than metrics derived from coarser-resolution datasets. Increased correlation in the latter half of the study period was partially attributable to increased streamflow variability in recent decades as well as to improved climate data quality across the interior mountain watersheds.

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Nolan T. Atkins
,
Justin M. Arnott
,
Ron W. Przybylinski
,
Ray A. Wolf
, and
Bradley D. Ketcham

Abstract

Single-Doppler radar along with damage observations are examined to investigate the structural evolution of vortices observed within the 29 June 1998 derecho event that propagated through southeastern Iowa into central and eastern Illinois. A total of 13 meso-γ-scale vortices observed primarily at low levels (0–3 km AGL) along the leading edge of the convective system were detected by the Weather Surveillance Radar-1988 Doppler (WSR-88D) radars at Davenport, Iowa, and Lincoln, Illinois. All but one of the vortices formed after the system evolved into a bow echo. Ten of the vortices formed north of the apex while three formed south of the apex. Seven of the vortices produced tornadoes that created F0–F1 surface damage. None of the vortices exhibited appreciable upscale growth. Careful analysis of the radar data suggests that it may be possible to discern between the tornadic and nontornadic vortices. The tornadic vortices tended to be stronger, longer-lived, and deeper than their nontornadic counterparts. The forecasting implications of these findings are discussed.

Single-Doppler radar observations documenting the evolution of midlevel (3–7 km AGL) “bookend” vortices associated with two embedded bow echoes are also presented. The first pair of midlevel vortices formed approximately 20 min after the time that the larger-scale convective system began its transition into a bow echo, had a lifetime of about 30 min, and was observed north of the primary bow apex. A second embedded bow echo formed approximately 20 min after the first, again north of the primary bow apex. The cyclonic member of this second embedded bow echo grew upscale and eventually became the dominant northern line-end vortex of the convective system. There appears to be no significant relationship or interaction between the low-level and midlevel vortices observed with this case.

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William E. Gartner
,
James E. Hoke
,
Norman W. Junker
, and
Louis E. Wolf

Abstract

No Abstract Available

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Robert J. Trapp
,
Dustan M. Wheatley
,
Nolan T. Atkins
,
Ronald W. Przybylinski
, and
Ray Wolf

Abstract

Postevent damage surveys conducted during the Bow Echo and Mesoscale Convective Vortex Experiment demonstrate that the severe thunderstorm wind reports in Storm Data served as a poor characterization of the actual scope and magnitude of the surveyed damage. Contrasting examples are presented in which a few reports grossly underrepresented a significant event (in terms of property damage and actual areal coverage of damage), while a large number of reports overrepresented a relatively less significant event. Explanations and further discussion of this problem are provided, as are some of the implications, which may include a skewed understanding of how and when systems of thunderstorms cause damage. A number of recommendations pertaining to severe wind reporting are offered.

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Jun Li
,
Walter W. Wolf
,
W. Paul Menzel
,
Wenjian Zhang
,
Hung-Lung Huang
, and
Thomas H. Achtor

Abstract

The International Advanced Television and Infrared Observation Satellite Operational Vertical Sounder (ATOVS) Processing Package (IAPP) has been developed to retrieve the atmospheric temperature profile, moisture profile, atmospheric total ozone, and other parameters in both clear and cloudy atmospheres from the ATOVS measurements. The algorithm that retrieves these parameters contains four steps: 1) cloud detection and removal, 2) bias adjustment for ATOVS measurements, 3) regression retrieval processes, and 4) a nonlinear iterative physical retrieval. Nine (3 × 3) adjacent High-Resolution Infrared Sounder (HIRS)/3 spot observations, together with Advanced Microwave Sounding Unit-A observations remapped to the HIRS/3 resolution, are used to retrieve the temperature profile, moisture profile, surface skin temperature, total atmospheric ozone and microwave surface emissivity, and so on. ATOVS profile retrieval results are evaluated by root-mean-square differences with respect to radiosonde observation profiles. The accuracy of the retrieval is about 2.0 K for the temperature at 1-km vertical resolution and 3.0–6.0 K for the dewpoint temperature at 2-km vertical resolution in this study. The IAPP is now available to users worldwide for processing the real-time ATOVS data.

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Kexin Zhang
,
Mitchell D. Goldberg
,
Fengying Sun
,
Lihang Zhou
,
Walter W. Wolf
,
Changyi Tan
,
Nicholas R. Nalli
, and
Quanhua Liu

Abstract

This study describes the algorithm for deriving near-real-time outgoing longwave radiation (OLR) from Cross-Track Infrared Sounder (CrIS) hyperspectral infrared sounder radiance measurements. The estimation of OLR on a near-real-time basis provides a unique perspective for studying the variability of Earth’s current atmospheric radiation budget. CrIS-derived OLR values are estimated as a weighted linear combination of CrIS-adjusted “pseudochannel” radiances. The algorithm uses the Atmospheric Infrared Sounder (AIRS) as the transfer instrument, and a least squares regression algorithm is applied to generate two sets of regression coefficients. The first set of regression coefficients is derived from collocated Clouds and the Earth’s Radiant Energy System (CERES) OLR on Aqua and pseudochannel radiances calculated from AIRS radiances. The second set of coefficients is derived to adjust the CrIS pseudochannel radiance to account for the differences in pseudochannel radiances between AIRS and CrIS. The CrIS-derived OLR is then validated by using a limited set of available CERES SNPP OLR observations over 1° × 1° global grids, as well as monthly OLR mean and interannual differences against CERES OLR datasets from SNPP and Aqua. The results show that the bias of global CrIS OLR estimation is within ±2 W m−2 and that the standard deviation is within 5 W m−2 for all conditions, and ±1 and 3 W m−2 for homogeneous scenes. The interannual CrIS-derived OLR differences agree well with Aqua CERES interannual OLR differences on a 1° × 1° spatial scale, with only a small drift of the global mean of these two datasets of around 0.004 W m−2.

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Andrea Schneidereit
,
Dieter H. W. Peters
,
Christian M. Grams
,
Julian F. Quinting
,
Julia H. Keller
,
Gabriel Wolf
,
Franziska Teubler
,
Michael Riemer
, and
Olivia Martius

Abstract

Tropospheric forcing of planetary wavenumber 2 is examined in the prephase of the major stratospheric sudden warming event in January 2009 (MSSW 2009). Because of a huge increase in Eliassen–Palm fluxes induced mainly by wavenumber 2, easterly angular momentum is transported into the Arctic stratosphere, deposited, and then decelerates the polar night jet. In agreement with earlier studies, the results reveal that the strongest eddy heat fluxes, associated with wavenumber 2, occur at 100 hPa during the prephase of MSSW 2009 in ERA-Interim. In addition, moderate conditions of the cold phase of ENSO (La Niña) contribute to the eddy heat flux anomaly. It is shown that enhanced tropospheric wave forcing over Alaska and Scandinavia is caused by tropical processes in two ways. First, in a climatological sense, La Niña contributes to an enhanced anticyclonic flow over both regions. Second, the Madden–Julian oscillation (MJO) has an indirect influence on the Alaskan ridge by enhancing eddy activity over the North Pacific. This is manifested in an increase in cyclone frequency and associated warm conveyor belt outflow, which contribute to the maintenance and amplification of the Alaskan anticyclone. The Scandinavian ridge is maintained by wave trains emanating from the Alaskan ridge propagating eastward, including an enhanced transport of eddy kinetic energy. The MSSW 2009 is an extraordinary case of how a beneficial phasing of La Niña and MJO conditions together with multiscale interactions enhances tropospheric forcing for wavenumber 2–induced zonal mean eddy heat flux in the lower stratosphere.

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