NOAA's National Climatic Data Center
Veach-Baley Federal Building
151 Patton Avenue
Asheville, NC 28801-5001
Telephone: +1 828.257.3140
Dr. Schreck completed his Ph.D. in 2010 at the University at Albany, State University of New York. His research investigates tropical weather and its impacts around the globe. In particular, he focuses on identifying and predicting the Madden–Julian Oscillation (MJO) and equatorial waves. Dr. Schreck engages with partners in the energy industry to explore how these systems can improve long-range forecasts of temperatures over the United States. He also uses NCDC’s International Best Track Archive for Climate Stewardship (IBTrACS) to explore the relationships between climate variability and tropical cyclones. As part of that work, Dr. Schreck is CICS-NC’s lead investigator on CycloneCenter.org, which invites citizen scientists to analyze historical tropical cyclone images.
Dr. Schreck joined CICS-NC in August 2010 as a Postdoctoral Fellow and has since transitioned to a Research Associate position in November 2012. He serves on the Climate Prediction Center’s global tropical hazards forecast team and as an Associate Editor for Monthly Weather Review.
This research uses novel satellite datasets to investigate tropical intra-seasonal variability, including the Madden–Julian Oscillation (MJO) and equatorial waves. Particular emphasis is placed on the relationship between the MJO and tropical cyclone activity in the Western Hemisphere. Daily monitoring of satellite-derived MJO signals provides a valuable tool for predicting tropical variability in the 5–30 day range.
The MJO has frequently been identified with proxies for convection such as outgoing longwave radiation (OLR). These data are suitable for the Eastern Hemisphere where deep tropical convection is commonplace. However, the convective signal becomes weaker in the Western Hemisphere, even as the signal persists in the upper troposphere. Inter-satellite calibration techniques have recently produced a homogeneous 32-year dataset of upper tropospheric water vapor (UTWV) from the high-resolution infrared radiation sounder (HIRS). These data are being used to develop a global view of the MJO.
The MJO significantly affects tropical cyclone activity around the globe. This project uses the UTWV data to identify how the MJO influences tropical cyclogenesis over the eastern North Pacific and the North Atlantic. Possible mechanisms include the local enhancement of convection and low-level vorticity, amplification of easterly waves, remote impacts on the vertical wind shear, and baroclinic effects. These issues are being explored through a case study of the record breaking Atlantic hurricane season in 2005.
Tropical cyclone activity is diagnosed using the International Best Track Archive for Climate Stewardship (IBTrACS) from NOAA’s National Climatic Data Center. IBTrACS combines tropical cyclone data from numerous international agencies. Operational procedures have evolved through time, and they vary greatly between agencies. Research is ongoing to document and mitigate these heterogeneities in the record.
A climatology of the MJO and equatorial waves in UTWV has been submitted to the Journal of Climate. Spectral analysis shows that the MJO and equatorial waves stand out above the low-frequency background in UTWV, similar to previous findings with OLR. The MJO and equatorial Rossby waves are associated with a greater fraction of the total variance in UTWV than in OLR. In the subtropics, UTWV identifies the subsidence drying that occurs poleward of the MJO’s convection. These signals are absent from OLR. For equatorial Rossby waves, the variance is more equatorially symmetric and less seasonally dependent in UTWV than in OLR. Kelvin waves, on the other hand, are overshadowed in UTWV by the extratropical Rossby waves that share similar propagation characteristics. These results demonstrate the utility of UTWV, in concert with OLR, for identifying tropical intra-seasonal variability.
A new website (http://monitor.cicsnc.org/mjo/) was developed and implemented for daily monitoring of the MJO and equatorial waves. This website applies established diagnostics to both UTWV and OLR. It has been tailored to meet the needs of forecasters at NOAA’s Climate Prediction Center (CPC). Special diagnostics have also been developed to support forecasts for the DYNAMO (Dynamics of the MJO) field campaign that was conducted over the Indian Ocean from October 2011 to March 2012.
Figure 1. Longitude–time Hovmšller diagrams of OLR (left) and UTWV (right) anomalies relative to their respective 1979–2011 daily climatologies. Both variables are averaged 15°S–15°N. Heavy black lines identify the convective (solid) and suppressed (dashed) phases of the MJO.
Figure 1 illustrates two longitude–time Hovmšller diagrams from the monitoring website. The left panel shows OLR, while the right panel presents UTWV brightness temperatures. In both cases, the shading indicates anomalies relative to their respective 32-year daily climatologies. Negative anomalies (cool shading) correspond to cold cloud tops in OLR and enhanced upper-level moisture in UTWV. In both cases, these negative values are generally associated with ascent.
Fortunately for the DYNAMO field campaign, the MJO was particularly active during October–December 2011. Tropical convection varies on a variety of time scales, but the heavy black lines in Fig. 1 roughly identify the convective (solid) and subsiding (dashed) phases of the MJO. The DYNAMO campaign was centered near 60°E where MJO’s convection initiates before it moves eastward. In OLR (left panel), the MJO signals weaken as they traverse the eastern Pacific (150°W–60°W). UTWV (right panel), on the other hand, tracks the signals more continuously around the globe. The positive and negative UTWV anomalies also have similar magnitudes, unlike OLR. UTWV is more sensitive to the subsiding branches of the tropical circulation, as demonstrated by the large positive (warm colors) anomalies near the dateline in December. These diagnostics provided a valuable forecasting tool during the field campaign.
The record-breaking 2005 Atlantic hurricane season provided an ideal testbed to examine the relationship between the MJO and tropical cyclones in the Western Hemisphere. During August, tropical cyclone development gradually shifted eastward from the eastern Pacific to the western Atlantic with the passage of the MJO’s convective envelope. This envelope circumnavigated the globe, and the pattern repeated in September–October. Ongoing research is examining the modulation of convection, low-level vorticity, and vertical wind shear by this MJO event. UTWV also indicates a connection between the MJO signals in the Northern Hemisphere and extratropical systems in the Southern Hemisphere. These relationships and their impacts on tropical cyclone activity will be explored further.
Research is also underway to produce a global climatology of tropical cyclones using IBTrACS. IBTrACS comprises historical tropical cyclone best-track data from numerous sources around the globe, including all of the Regional Specialized Meteorological Centers (RSMCs). It represents the most complete amalgamation of tropical cyclone data compiled to date. IBTrACS offers a unique opportunity to revisit the global climatology of tropical cyclones. This research is exploring the mean annual global tropical cyclone activity as well as interannual variability within each basin. Discrepancies between sources in IBTrACS are being identified in order to motivate future reanalysis efforts.
Schreck, C. J., L. Shi, J. P. Kossin, and J. J. Bates, 2011: Tropical intraseasonal variability in outgoing longwave radiation and upper tropospheric water vapor. J. Climate, Submitted.
Ventrice, M. J., C. D. Thorncroft, and C. J. Schreck, 2011: Impacts of convectively coupled Kelvin waves on environmental conditions for Atlantic tropical cyclogenesis. Mon. Wea. Rev., In Press.
Aiyyer, A., A. Mekonnen, and C. J. Schreck, 2012: Projection of tropical cyclones on wavenumber-frequency filtered equatorial waves. J. Climate, In Press.
Schreck, C. J., J. Molinari, and A. Aiyyer, 2012: A global view of equatorial waves and tropical cyclogenesis. Mon. Wea. Rev., 140, 774-788.