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Richard Heim Jr.

The personal computer (PC) has become an important part of meteorological observing, telecommunications, forecasting, research, and data-management systems. The National Climatic Data Center (NCDC) is the nation's quality-control and archival facility for weather data. NCDC's digital archive consists of more than 200 data sets which are stored on over 50 000 reels of high-density magnetic tape. Its size and complexity make on-line access to the complete archive via PC and modem impractical. However, NCDC recognizes the growing importance of PCs in climatic applications and, since 1984, has made selected data sets available in a PC-readable format.

The data sets available on diskette fall into the following broad categories: hourly observations, daily observations, derived quantities, and summary statistics. The period of record varies with each data set and with each station. In the digital archive, daily observations generally begin in the late 1800's to the early 1900's, and hourly observations generally begin in the mid 1900's.

A review of NCDC data operations and products puts the digital archive into an operational perspective. The two formats (BASIC sequential element, and fixed-position fields) in which data-set diskettes are available are summarized. BASIC–sequential-element files can be “imported” into a LOTUS-type spreadsheet.

NCDC is also responsible for describing the nation's climate. These functions have been condensed into a climatological data-management and analysis software package, called CLICOM, which can be run on a PC.

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Richard R. Heim Jr.

Abstract

The United States experienced a severe drought that peaked in 2012 and was characterized by near-record extent, record warmth, and record dryness in several areas. For some regions, the 2012 drought was a continuation of drought that began in earlier years and continued through 2014. The 1998–2014 drought episode is compared to the two other major drought episodes of the twentieth century in terms of duration, areal extent, intensity, and spatial pattern using operational datasets produced by the National Oceanic and Atmospheric Administration/National Centers for Environmental Information. It is characterized by more short-term dryness, more concurrent (regional) wetness, and warmer temperatures than the other two drought episodes. The implications of these differences for water resource managers and decision-makers are discussed.

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Richard R. Heim Jr.

The monitoring and analysis of drought have long suffered from the lack of an adequate definition of the phenomenon. As a result, drought indices have slowly evolved during the last two centuries from simplistic approaches based on some measure of rainfall deficiency, to more complex problem-specific models. Indices developed in the late nineteenth and early twentieth century included such measures as percent of normal precipitation over some interval, consecutive days with rain below a given threshold, formulae involving a combination of temperature and precipitation, and models factoring in precipitation deficits over consecutive days. The incorporation of evapotranspiration as a measure of water demand by Thornthwaite led to the landmark development in 1965 by Palmer of a water budget-based drought index that is still widely used. Drought indices developed since the 1960s include the Surface Water Supply Index, which supplements the Palmer Index by integrating snowpack, reservoir storage, streamflow, and precipitation at high elevations; the Keetch–Byram Drought Index, which is used by fire control managers; the Standardized Precipitation Index; and the Vegetation Condition Index, which utilizes global satellite observations of vegetation condition. These models continue to evolve as new data sources become available. The twentieth century concluded with the development of the Drought Monitor tool, which incorporates Palmer's index and several other (post Palmer) indices to provide a universal assessment of drought conditions across the entire United States. By putting the development of these drought indices into a historical perspective, this paper provides a better understanding of the complex Palmer Index and of the nature of measuring drought in general.

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Kenneth F. Dewey
and
Richard Heim Jr.

The purpose of this article is to acquaint the research community with a new data base—a digitized archive of Northern Hemisphere snow cover. Historically, those researchers who needed snow cover data for climatic and atmospheric boundary layer studies have had to rely on the irregularly spaced (and in some regions, sparse) grid of point observations. Northern Hemisphere Weekly Snow and Ice Cover Charts, which are created from analyzed satellite imagery at the National Earth Satellite Service (NESS), have been available on an operational basis since late 1966. Each of these weekly charts for the period November 1966 through December 1980 was digitized and stored in a new data archive. Snow cover area and snow cover frequency climatologies were created and examples are presented. The significance of this unique data archive is examined by comparing the 14-year mean annual snow cover frequency climatology with several published snow cover climatologies. The potential uses for this data archive in meteorological and climatological studies also are reviewed.

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Michael J. Brewer
and
Richard R. Heim, Jr.

No Abstract available.

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Richard R. Heim Jr.
and
Michael J. Brewer

Abstract

The international scientific community has long recognized the need for coordinated drought monitoring and response, but many factors have prevented progress in the development of a Global Drought Early Warning System (GDEWS): some of which involve administrative issues (coordinated international action and policy) while others involve scientific, technological, and logistical issues. The creation of the National Integrated Drought Information System (NIDIS) Portal within the United States provided an opportunity to take the first steps toward building the informational foundation for a GDEWS: that is, a Global Drought Information System (GDIS). At a series of workshops sponsored by the World Meteorological Organization (WMO) and Group on Earth Observations (GEO) held in Asheville, North Carolina, in April 2010, it was recommended that a modular approach be taken in the creation of a GDIS and that the NIDIS Portal serve as the foundation for the GDIS structure. Once a NIDIS-based Global Drought Monitor (GDM) Portal (GDMP) established an international drought clearinghouse, the various components of a GDIS (drought monitoring, forecasting, impacts, history, research, and education) and later a GDEWS (drought relief, recovery, and planning) could be constructed atop it. The NIDIS Portal is a web-based information system created to address drought services and early warning in the United States, including drought monitoring, forecasting, impacts, mitigation, research, and education. This portal utilizes Open Geospatial Consortium (OGC) web mapping services (WMS) to incorporate continental drought monitors into the GDMP. As of early 2012, the GDM has incorporated continental drought information for North America (North American Drought Monitor), Europe (European Drought Observatory), and Africa (African Drought Monitor developed by Princeton University); interest has been expressed by groups representing Australia and South America; and coordination with appropriate parties in Asia is also expected. Because of the range of climates across the world and the diverse nature of drought and the sectors it impacts, the construction and functioning of each continental drought monitor needs to be appropriate for the continent in question. The GDMP includes a suite of global drought indicators identified by experts and adopted by the WMO as the necessary measures to examine drought from a meteorological standpoint; these global drought indicators provide a base to assist the global integration and interpretation of the continental drought monitors. The GDMP has been included in recent updates to the GEO Work Plan and has benefited from substantial coordination with WMO on both their Global Framework for Climate Services and the National Drought Policy efforts. The GDMP is recognized as having the potential to be a major contributor to both of these activities.

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David A. Robinson
,
Kenneth F. Dewey
, and
Richard R. Heim Jr.

Accurate monitoring of the large-scale dimensions of global snow cover is essential for understanding details of climate dynamics and climate change. Presently, such information is gathered individually from ground station networks and satellite platforms. Efforts are in progress to consolidate and analyze long-term station records from a number of countries. To gain truly global coverage, however, satellite-based monitoring techniques must be employed. A 27-year record of Northern Hemisphere continental snow cover produced by the National Oceanic and Atmospheric Administration (NOAA) is the longest such environmental record available. Records of Southern Hemisphere continental cover and snow on top of Arctic sea ice have been produced by similar means for a portion of this interval. The visible imagery charting technique used to generate these data provides information on snow extent but not on snow volume. Satellite microwave analyses over Northern Hemisphere lands show some promise in this regard, however, large-scale monitoring of snow extent with microwave data remains less accurate than visible charting.

This paper updates the status of global snow cover monitoring, concentrating on the weekly snow charts prepared by NOAA and discussing a new and consistent record of monthly snow cover generated from these weekly charts. The NOAA charts show a reduction of hemispheric snow cover over the past five years, particularly in spring. Snow areas from the NOAA product are then compared with values derived using passive microwave data. The latter consistently reports less snow cover than the more accurate visible product. Finally, future snow monitoring initiatives are recommended. These include continuing the consistent NOAA product until an all-weather all-surface product is developed. The latter would use multiple data sources and geographic information systems techniques. Such an integrative product would need extensive comparisons with the NOAA product to ensure the continued utility of the lengthy NOAA observations in studies of climate change. In a retrospective sense, satellite charts from the middle 1960s to early 1970s need reevaluation and techniques to merge satellite products with historic station time series must be developed.

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Thomas R. Karl
,
Pavel Ya Groisman
,
Richard W. Knight
, and
Richard R. Heim Jr.

Abstract

Contemporary large-scale changes in solid and total precipitation and satellite-derived snow cover were examined over the North American continent. Annual snow cover extent over the last 19 years decreased up to 6×105 km2 relative to a 0.93°C (0.33°C) increase in North American (Northern Hemisphere) temperature.

A strong correlation exists between snow cover and temperature where up to 78% of the variance in regional snow cover and snowfall is explained by the anomalies of monthly mean maximum temperature. Over the last two decades the decrease in snow cover during winter (December-March) has largely occurred through reduced frequency of snow cover in areas that typically have a high probability of snow on the ground with little change in the frequency of snow cover in other areas. Similar characteristics were observed during spring (April-May) in areas with high snow cover probability except for an expansion of the snow-free regions. Anomalies in these two seasons dominate the interannual variability (nearly three-fourths of the variance) of snow cover.

The apparent unprecedented global warmth of the 1980s was accompanied by a retreat of the mean annual North American snow cover, a 10% increase in annual Alaskan precipitation, a significant decrease (−7% ) in annual snowfall over southern Canada (while the total precipitation remained above normal), and a more than twofold increase in the variance of the ratio of frozen to total precipitation over the contiguous United States. An increase (4% –5% per decade) of both solid and total precipitation over northern Canada (zone 55°–70°N) occurred during the last four decades. A century-scale increase (1% per decade) of precipitation was found over southern Canada, but the proportion of the precipitation that falls in frozen form over this area decreased over the last four decades. Precipitation over the contiguous United States has significantly (2% –3% per decade) increased during the last four decades, but on a century time scale the increasing trend is not yet statistically significant.

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Jay Lawrimore
,
Richard R. Heim Jr.
,
Mark Svoboda
,
Val Swail
, and
Phil J. Englehart
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Michael C. Kruk
,
Britt Parker
,
John J. Marra
,
Kevin Werner
,
Richard Heim
,
Russell Vose
, and
Philip Malsale

Abstract

Within the realm of climate and environmental sciences, stakeholder engagement has traditionally been given a relative low priority in favor of generating tools, products, and services following the longstanding practice of pushing out information in the hopes users will pull it into their decision toolkits. However, the landscape is gradually shifting away from that paradigm and toward one in which the stakeholder community is more directly involved in the production of products and services with the scientific organization. This mutual learning arrangement, referred to as the coproduction of knowledge, has been applied to two user engagement activities within the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) and the NOAA Office of Coastal Management (OCM) Coral Reef Conservation Program (CRCP). The iterative nature of such dialogues helped scientists within NCEI and OCM to better understand user requirements and as a result generate climate information that was locally relevant and regionally applicable. The recent engagement activities exemplified the benefits of a robust and sustained relationship between climate scientists and the user community. They demonstrate that the interactions between the two led to the empowerment of the local community to shape and mold climate information products as well as further enhancing user buy in of these products and services with which local agriculture and food security, disaster risk reduction, energy, health, and water decisions are being made. This coproduction of knowledge model for user engagement activities also serves to build trust between the scientific and user communities.

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