Global Precipitation Means and Variations with the
Description: Global Precipitation Means and Variations with the New Version of GPCP Robert Adler1, Guojun Gu1, George Huffman2, Ali Behrangi3, David Bolvin2, Jian-Jian Wang1, Eric Nelkin2 1U. of Maryland, 2NASAGoddard, 3U. of Arizona Global
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slide1. Global Precipitation Means and Variations with the New Version of GPCP
Robert Adler1, Guojun Gu1, George Huffman2, Ali Behrangi3, David Bolvin2, Jian-Jian Wang1, Eric Nelkin2
1U. of Maryland, 2NASA/Goddard, 3U. of Arizona Global Precipitation Climatology Project (GPCP) Monthly Product is an observational-based, blended analysis using satellite (over ocean and land) and gauge (over land) information GPCP analysis used in ~5000 journal papers GPCP V3 climatology
(1983-2020) Development of GPCP V3 sponsored by NASA MEaSUREs program<br>
slide2. Version 3.2 of the Global Precipitation Climatology Project (GPCP) Monthly Analysis (1983-2019) Key Features • Finer spatial resolution (0.5º latitude/longitude)
• Updated satellite algorithms, including GPROF applied to SSMI and SSMIS, but adjusted by V2 PMW algorithm (METH) for consistency
• Latest gauge analysis over land from the Global Precipitation Climatology Center (GPCC) in Germany
• Improved high-latitude analysis with improved satellite analysis and modified wind-loss gauge adjustments
• Fraction of frozen precipitation estimated from reanalysis surface temperature/moisture information (post-1992)
• Ocean estimates adjusted using climatologies from the Tropical Rainfall Measuring Mission (TRMM), the Global Precipitation Measurement (GPM) mission and CloudSat. “Old” GPCP V2.3 will continue (for a while) and is compared to V3.2 in this talk
V2 is part of NOAA’s Climate Data Record (CDR) program [Available from Goddard Disc]<br>
slide3. Version 3 Climatology compared to V2 Climatology (1983-2020) V3
New V2
Old V3-V2 • Small changes over land
• General increases over ocean with small decreases in drier zones
• Increases along ITCZ
• Increases in mid-latitude ocean maxima
• Decrease along 60S related to artifact in V2<br>
slide4. Zonal Climatology (Land+Ocean) mm/d % difference (V3-V2) • New Global Total: 2.8 mm/d (4.5% higher than V2)
• Tropics higher by ~4 %
• Mid-latitude peaks higher
• Southern Hemisphere peak is shifted toward Equator, eliminating artificial peak at 60S in V2<br>
slide5. Land mm/d % difference (V3-V2) • Minor changes over land due to coasts and merger with satellite estimates
• Land lower by ~ 1 % mainly due to smaller wind loss adjustments over northern Asia<br>
slide6. Ocean mm/d % difference
(V3-V2) • All significant changes in climatological means are over ocean
• Oceans higher by ~6.5 %
• ITCZ peaks higher
• Mid-latitude peaks higher
• Southern Hemisphere peak shifts toward Equator, eliminating artificial peak at 60S in V2 Ocean changes in mean values due almost entirely to TRMM/GPM and CloudSat<br>
slide7. Annual Global Precipitation (1983-2020) • Small positive trend in total global precipitation
• Global anomalies related to ENSO (peak during El Ninos)
• Land and ocean anomalies partially compensate Pinatubo El Nino El Nino<br>
slide8. Estimated Trend in Global Snowfall (1992-2020) ?? Needs additional analysis and validation<br>
slide9. Regional Trends for 1983-2020 for V3 and V2 • Although near zero trend in global total precipitation, significant regional trends
• V3 trend pattern and magnitude very close to V2 trends, subtle differences exist
• ITCZ and W. Pac. Increases, also Indian Ocean; decreases in S. Pacific and mid- latitude cyclone tracks V3 V2<br>
slide10. Trend Maps (1983-2014)—GPCP compared to AMIP and CMIP • GPCP confirms major AMIP trend patterns (e.g., tropical/mid-latitude Pacific, North/South America), but differs in other areas (e.g., South Asia)
• GPCP differs from CMIP mainly due to inter-decadal effects (e.g., PDO/AMO) GPCP AMIP CMIP<br>
slide11. Back to Global Mean Precipitation
• ~ 15 years ago Kevin and company did some of the first estimates of global water/energy cycles using satellite data (including GPCP)
• But he increased the GPCP estimate of climatological mean by 5% (over ocean) to make things balance
• So now (finally) our new GPCP V3 confirms his adjustment GPCP GPCP J. Hydromet.<br>
slide12. Back to Global Mean Precipitation
• ~ 15 years ago Kevin and company did some of the first estimates of global water/energy cycles using satellite data (including GPCP)
• But he increased the GPCP estimate of climatological mean by 5% (over ocean) to make things balance
• So now (finally) our new GPCP V3 confirms his adjustment GPCP GPCP J. Hydromet. Kevin was Right! GPCP V3 has global total increase by ~4% (oceans by ~ 6%)<br>
Robert Adler1, Guojun Gu1, George Huffman2, Ali Behrangi3, David Bolvin2, Jian-Jian Wang1, Eric Nelkin2
1U. of Maryland, 2NASA/Goddard, 3U. of Arizona Global Precipitation Climatology Project (GPCP) Monthly Product is an observational-based, blended analysis using satellite (over ocean and land) and gauge (over land) information GPCP analysis used in ~5000 journal papers GPCP V3 climatology
(1983-2020) Development of GPCP V3 sponsored by NASA MEaSUREs program<br>
slide2. Version 3.2 of the Global Precipitation Climatology Project (GPCP) Monthly Analysis (1983-2019) Key Features • Finer spatial resolution (0.5º latitude/longitude)
• Updated satellite algorithms, including GPROF applied to SSMI and SSMIS, but adjusted by V2 PMW algorithm (METH) for consistency
• Latest gauge analysis over land from the Global Precipitation Climatology Center (GPCC) in Germany
• Improved high-latitude analysis with improved satellite analysis and modified wind-loss gauge adjustments
• Fraction of frozen precipitation estimated from reanalysis surface temperature/moisture information (post-1992)
• Ocean estimates adjusted using climatologies from the Tropical Rainfall Measuring Mission (TRMM), the Global Precipitation Measurement (GPM) mission and CloudSat. “Old” GPCP V2.3 will continue (for a while) and is compared to V3.2 in this talk
V2 is part of NOAA’s Climate Data Record (CDR) program [Available from Goddard Disc]<br>
slide3. Version 3 Climatology compared to V2 Climatology (1983-2020) V3
New V2
Old V3-V2 • Small changes over land
• General increases over ocean with small decreases in drier zones
• Increases along ITCZ
• Increases in mid-latitude ocean maxima
• Decrease along 60S related to artifact in V2<br>
slide4. Zonal Climatology (Land+Ocean) mm/d % difference (V3-V2) • New Global Total: 2.8 mm/d (4.5% higher than V2)
• Tropics higher by ~4 %
• Mid-latitude peaks higher
• Southern Hemisphere peak is shifted toward Equator, eliminating artificial peak at 60S in V2<br>
slide5. Land mm/d % difference (V3-V2) • Minor changes over land due to coasts and merger with satellite estimates
• Land lower by ~ 1 % mainly due to smaller wind loss adjustments over northern Asia<br>
slide6. Ocean mm/d % difference
(V3-V2) • All significant changes in climatological means are over ocean
• Oceans higher by ~6.5 %
• ITCZ peaks higher
• Mid-latitude peaks higher
• Southern Hemisphere peak shifts toward Equator, eliminating artificial peak at 60S in V2 Ocean changes in mean values due almost entirely to TRMM/GPM and CloudSat<br>
slide7. Annual Global Precipitation (1983-2020) • Small positive trend in total global precipitation
• Global anomalies related to ENSO (peak during El Ninos)
• Land and ocean anomalies partially compensate Pinatubo El Nino El Nino<br>
slide8. Estimated Trend in Global Snowfall (1992-2020) ?? Needs additional analysis and validation<br>
slide9. Regional Trends for 1983-2020 for V3 and V2 • Although near zero trend in global total precipitation, significant regional trends
• V3 trend pattern and magnitude very close to V2 trends, subtle differences exist
• ITCZ and W. Pac. Increases, also Indian Ocean; decreases in S. Pacific and mid- latitude cyclone tracks V3 V2<br>
slide10. Trend Maps (1983-2014)—GPCP compared to AMIP and CMIP • GPCP confirms major AMIP trend patterns (e.g., tropical/mid-latitude Pacific, North/South America), but differs in other areas (e.g., South Asia)
• GPCP differs from CMIP mainly due to inter-decadal effects (e.g., PDO/AMO) GPCP AMIP CMIP<br>
slide11. Back to Global Mean Precipitation
• ~ 15 years ago Kevin and company did some of the first estimates of global water/energy cycles using satellite data (including GPCP)
• But he increased the GPCP estimate of climatological mean by 5% (over ocean) to make things balance
• So now (finally) our new GPCP V3 confirms his adjustment GPCP GPCP J. Hydromet.<br>
slide12. Back to Global Mean Precipitation
• ~ 15 years ago Kevin and company did some of the first estimates of global water/energy cycles using satellite data (including GPCP)
• But he increased the GPCP estimate of climatological mean by 5% (over ocean) to make things balance
• So now (finally) our new GPCP V3 confirms his adjustment GPCP GPCP J. Hydromet. Kevin was Right! GPCP V3 has global total increase by ~4% (oceans by ~ 6%)<br>