An Overview of GMDs Water Vapor Research Dale Hurst, Emrys Hall, - - PowerPoint PPT Presentation

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An Overview of GMDs Water Vapor Research Dale Hurst, Emrys Hall, - - PowerPoint PPT Presentation

May 09, 2023 383 likes •552 views

An Overview of GMDs Water Vapor Research Dale Hurst, Emrys Hall, Allen Jordan CIRES, University of Colorado & Global Monitoring Division, NOAA ESRL Thanks to: NASA UACO program NOAA CPO GMAC and GMD Review May 23, 2018 Scientific Goal

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An Overview of GMD’s Water Vapor Research

Dale Hurst, Emrys Hall, Allen Jordan

GMAC and GMD Review May 23, 2018

CIRES, University of Colorado & Global Monitoring Division, NOAA ESRL Thanks to: NASA UACO program NOAA CPO

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Scientific Goal

Monitor and understand the inter-annual and longer-term variability of water vapor in the upper troposphere and stratosphere

Why?

Water vapor is a very powerful greenhouse gas, especially in the very cold region near the tropopause

How?

Balloon-borne NOAA Frost Point Hygrometers (FPHs)

Where?

Boulder, Colorado; Hilo, Hawaii; Lauder, New Zealand

When?

1-2 soundings per month at each site SWV influences stratospheric O3 - polar (PSCs) and global (HOx)

GMAC and GMD Review May 23, 2018

2/12

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Water Vapor in the Stratosphere

How is it removed?

  • Recirculation (Brewer-Dobson Circulation)
  • Photo-dissociation by Lyman-α radiation (Mesosphere)
  • Dehydration within Antarctic vortex during winter/spring

What controls its distribution?

  • Strengths and Phases of BDC, QBO, ENSO (Seasonal, Inter-annual)
  • > influences on tropical coldpoint (minimum) temperatures
  • Amounts of CH4 and H2 that have been oxidized (Height-dependent)
  • Strengths of deep convection, Antarctic dehydration, Asian monsoon

How does it get there?

  • Slow vertical transport (Brewer-Dobson Circulation)
  • Fast cross-tropopause transport (Deep Convective Ice Lofting)
  • Isentropic transport through tropopause breaks
  • In situ oxidation of CH4 and H2 in the stratosphere

GMAC and GMD Review May 23, 2018

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Water Vapor–Climate Feedback

Stratospheric Water Vapor (<0.1% of atmospheric burden)

  • Strong IR absorber of OLR, weak thermal emission to space
  • Climate change to warm the tropical tropopause and increase SWV
  • Additional SWV absorbs more OLR

Changes in SWV have a significant impact on surface temperatures Tropospheric Water Vapor (>99.9% of atmospheric burden)

  • Strong IR absorber of outgoing long-wave radiation (OLR)
  • Increased surface and tropospheric temperatures adds WV
  • Additional WV absorbs more OLR

The ~1 ppm (~25%) increase in SWV between 1980 and 2000 would have enhanced the rate of surface warming in the 1990s by ~30%

GMAC and GMD Review May 23, 2018

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Solomon et al. (2010)

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How GMD Measures Water Vapor

Balloon-Borne Frost Point Hygrometers (FPH)

  • 1854: First dew point hygrometer developed in Germany
  • 1947: First FPH capable of measuring SWV (<10 ppm)
  • 1960-70s: Mastenbrook and Oltmans developed balloon-borne FPH at NRL
  • 1980: Oltmans begins routine FPH soundings in Boulder
  • 1989->: FPH performance improved: digital logic, stable frost control
  • Every NOAA FPH is built and bench-tested at GMD. 40-50 per year

FPH Air Flow Tube (also on bottom) Ozonesonde Radiosonde FPH Cryogen Dewar FPH Mirror Assembly (internal)

GMAC and GMD Review May 23, 2018

PID Logic Tube

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Lauder Hilo Boulder Where GMD Measures Water Vapor NOAA FPH sites Boulder 40°N since 1980

(~monthly profiles)

Hilo 20°N since 2010 Lauder 45°S since 2004 Lauder Hilo Boulder

Sodankylä San José Lindenberg

Other sites (using CFH) Sodankylä 67°N since 2002

(with >5 years of monthly profiles)

Lindenberg 52°N since 2008 San José 10°N since 2005

GMAC and GMD Review May 23, 2018

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Water Vapor Vertical Profiles

GMAC and GMD Review May 23, 2018

Altitude (km) Water Vapor (ppmv)

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FPH Measurement Accuracy and Uncertainties

Near-global coverage from 1984 onward

from Hall et al. (2016) Systematic Random

Laboratory Comparison AQUAVIT-2 (2013)

GMAC and GMD Review May 23, 2018 from Hall et al. (2016)

FPH Measurement Accuracy

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Trends of 0.20 – 0.25 ppm decade-1

Scientific Findings

GMAC and GMD Review May 23, 2018 updated from Hurst et al. (2011)

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FPH and CFH vs MLS, 68 hPa

GMAC and GMD Review May 23, 2018 from Hurst et al. (2016)

Spatial Coincidence Criteria ∆lat < 2° ∆lon < 8° Temporal Matching ∆t < 18h 10/12

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GMAC and GMD Review May 23, 2018

FPs vs MLS: Post-2010 Drifts

adapted from Hurst et al. (2016)

Full-Record Biases

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Summary Photo by Patrick Cullis, GMD Boulder record: SWV increase of ~20% since 1980 Measurement uncertainties <6% (2σ) in the stratosphere Only 6 FP sites world-wide with records >5 years GMD: 1-2 FPH launches/month at 3 sites. 38 years at BLD FPs and MLS began diverging ~2010 (1-2% yr-1) WV near the tropopause is a powerful GHG (+feedback) FPs–MLS biases up to 0.4 ppm (10%) below 23 km

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SLIDE 13

GMAC and GMD Review May 23, 2018

Extra Slides

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SLIDE 14

PC

PC

40-channel multiplexer

1234 2459 3456 4675 6857

EtOH & Dry Ice & LN2

  • 100°C

Motorized Mixer Thermistors 35 New 4 Archived 1 NIST-calibrated

Calibration Range: -100 to +20° C (takes ~36 hours)

Ensuring Long-Term FPH Measurement Accuracy

Calibration of mirror thermistors

GMAC and GMD Review May 23, 2018

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FP vs Satellite Drifts

adapted from Hurst et al. (2016)

Statistical Breakpoints FPH – MLS

GMAC and GMD Review May 23, 2018